big block chevy info

Discussion in 'Blocks' started by grumpyvette, Nov 14, 2008.

  1. grumpyvette

    grumpyvette Administrator Staff Member

    the real basics, (off ebays site)-------------------------------------------------------------------------------
    "
    This guide is intended to help you sort out the more major differences among Big Block Chevrolet engines produced since 1958. Chevrolet has designed and produced several different "big block" engine families. Within each family, there can be evolutionary changes, and special parts designed for competition use which may not be directly interchangeable with the regular production items. I don't intend to cover every possible variation. For practical purposes, all big block Chevrolet engines use a cylinder bore spacing of 4.84 inches although note the one exception below.

    Early engines were designated as Mark I, (Mk I) Mk II, Mk III, and Mk IV. Later engines continued the numbering system as Generation 5 (Gen 5), Gen 6, Gen 7. There are some conflicting theories as to the reason for the change from "Mark" to "Generation". My first guess: "Gen 5" sounds much more modern, hi-tech, and trendy than "Mk V".

    Mark I: The original "Big Block Chevy", also called the "W" engine perhaps because of the layout of the valves and therefore the shape of the valve covers--although another possibility is that GM chose the "W" prototype for production rather than the competing "X" or "Y" prototypes, and therefore it's a convenient coincidence that the valve layout is in the shape of a "W". It should be noted that this engine became "Mark I" only after the Mark II was being designed years after the "W" was introduced. Whatever the origin of the name, this engine family was installed in vehicles beginning in 1958, as a 348. In 1961, it went to 409 cubic inches, (as immortalized in the Beach Boys song "She's so fine, my 409") and for one year only (1963) a few well-connected racers could buy a car with a 427 cubic inch version called the Z-11. The 427 version was all about performance, and had special parts which were not directly interchangeable with the 348/409. While production of the 427 was severely limited, both the 348 and 409 were offered in passenger cars and light- and medium-duty trucks. The truck blocks were somewhat different from the passenger car blocks, having slightly different water jackets and of course, lower compression achieved by changes in the piston in addition to more machining of the top of the cylinder. A novel feature of this engine is that the top of the cylinders are not machined at a 90 degree angle to the bore centerline. The top of the cylinder block is machined at a 16 degree angle, and the cylinder head has almost no "combustion chamber" cast into it. The combustion chamber is the top wedge-shaped section of the cylinder. Ford also introduced an engine family like that in '58--the Mercury/Edsel/Lincoln "MEL" 383/410/430/462. The "W" engine ended it's automotive production life part way through the 1965 model year, when the 409 Mk I was superseded by the 396 Mk IV engine.

    Mark II: This is more of a prototype than a production engine. It is the 1963-only "Mystery Engine" several of which ran the Daytona 500 race, and in fact won the 100-mile qualifier setting a new record. It is largely the result of engineering work by Dick Keinath. Produced mainly as a 427 but with a few 396 and 409 cubic inch versions, all in VERY limited numbers. Even though it was intended as a NASCAR-capable engine, it had 2-bolt main caps. This engine was never installed in a production-line vehicle by GM, it only went to racers. And even though it was available in 1963, it has very little resemblance to the 427 Mark I "W" engine of the same year. The Mark II was a "breakthrough" design using intake and exhaust valves that are tilted in two planes--a canted-valve cylinder head, nicknamed the "Semi-Hemi" or "Porcupine" because it is "almost" a hemi head, and the valve stems stick out of the head casting at seemingly random angles. The engine was the subject of an extensive article in the May, 1963 Hot Rod Magazine. Because of NASCAR politics, Chevrolet was forced to sell two 427 Mark II engines to Ford after the '63 Daytona race, (to "prove" that it was a production engine, and therefore eligible to race in NASCAR events) and so this engine is not only the grandfather of the Mark IV and later big block Chevies, it's also the grandfather of the canted-valve Ford engines: Boss 302, 351 Cleveland and variants, and the 429/460 big block Ford. The bore and stroke of the 427 MK II is not the same as the 427 MK IV.

    Mark III: Never released for production. This was rumored to be the result of GM/Chevrolet's proposed buyout of the tooling and rights to the Packard V-8 engine of the mid-to-late '50's. The Packard engine was truly huge, having 5" bore centers. The former president of Packard wound up at Ford after Packard folded, perhaps because of that, Ford was also interested in this engine. Ford wanted to make a V-12 variant from it just as Packard had once envisioned. One way or another, neither GM nor Ford actually went forward with the purchase.

    Mark IV: The engine that most people think of as the "big block Chevy". Released partway into the 1965 model year as a 396, superseding the older 409. It is a development of the Mark II and using similar but not identical canted valve (semi-hemi/porcupine) cylinder heads. It was later expanded to 402 (often still labeled as a 396, or even a 400,) a 427, a 454, and a few "special" engines were produced in the late '60's for offshore boat racing as a 482. There was a 366 and a 427 version that each had a .400 taller deck height to accommodate .400 taller pistons using four rings instead of the more usual three rings. These tall-deck engines were used only in medium-duty trucks (NOT in pickup trucks--think in terms of big farm trucks, garbage trucks, dump trucks, school busses, etc.) The tall-deck blocks all had 4-bolt main caps, forged crankshafts, and the strongest of the 3/8 bolt connecting rods. All-out performance engines used 7/16 bolt connecting rods, along with other changes. This engine family was discontinued in 1990, with the Gen 5 appearing in 1991.
    BTW, , on BIG BLOCKS the oil pumps and oil filter adapters are different due to the block oil filter recess and rear seals being different
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    There are gaskets made specifically for this swap. Use other gaskets at you're own risk- these are what you want (from a V/R press release, presumably prior to the Gen 6 engine release):
    DART BIG M BBC BLOCK
    Features:
    • Siamesed Extra-Thick Cylinder Walls: Resists cracking and improves ring seal (minimum .300'' thick with 4.625'' bore).
    • Scalloped Outer Water Jacket Walls: Improves coolant flow around the cylinder barrels to equalize temperatures.
    • Four-Bolt Main Bearing Caps: In steel or ductile iron have splayed outer bolts for extra strength.
    • Crankshaft Tunnel: Has clearance for a 4.500'' stroke crank with steel rods without grinding.
    • True ''Priority Main'' Oil System: Lubricates the main bearings before the lifters.
    • Oil Filter Pad: Drilled and tapped for an external oil pump.
    • Rear Four-Bolt Cap: Uses standard oil pump and two-piece seal - no adapter required!
    • Lifter Valley Head Stud Bosses: Prevent blown head gaskets between head bolts.
    • External Block Machining: Reduces weight without sacrificing strength.
    • Simplified Install : Fuel pump boss, clutch linkage mounts and side & front motor mounts simplfy installation on any chassis.
    • Dual Oil Pan Bolt Patterns: Fits standard and notched oil pans.
    • Bellhousing Flange and Rear Main Bearing: Reinforced with ribs to resist cracks.
    • Note: Does not include cam bearings, freeze plugs, or dowels
    General Motors 7.4L Head Gasket
    Issue:

    General Motors (GM) 7.4L (454 CID) engines use two types of engine blocks: the Mark IV and Mark V.
    The Mark IV is found on 7.4L engines in model years from 1965 to 1990,
    and
    the Mark V is found on 7.4L engines in model years from 1991 and newer.

    Often, installers will attempt to adapt a.
    Mark IVcylinder head for a Mark V block.
    This conversion can be made if attention is paid to the coolant circulation
    .
    Mark IV and Mark V have different coolant flows,
    and were originally designed for different head gaskets.
    If the conversion is not performed correctly,
    the engine will overheat, causing premature engine wear and damage.

    Resolution:
    Victor Reinz has designed two Nitroseal® head gaskets to specifically allow for this conversion.

    The installation requires Victor Reinz part number 4918 be installed on the right cylinder bank,
    to maintain proper coolant circulation, and part number 4923 ,
    to be installed on the left cylinder bank
    for the correct coolant flow.

    Application:
    Victor Reinz part numbers 4918(right bank)
    and
    4923 (left bank)

    are available for GM 7.4L (454 CID)
    engines.
    mark iv blocks
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    mark v blocks
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    (keep in mind that ALL '91 and later Gen.V and Gen.VI big blocks come with 4-bolt main caps. The two-bolt big blocks are no longer in production
    MANY BUT NOT ALL aftermarket head designs have been modified to work on both the early MARK IV 1965-90 and later MARK V & VI blocks 1991-later.)

    BTW, , on BIG BLOCKS the oil pumps and oil filter adapters are different due to the block oil filter recess and rear seals being different
    GEN 4 or MARK IV
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    GEN V and VI
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    Gen 5: General Motors made substantial revisions to the Mark IV engine, and the result was christened "Gen 5" when it was released for the 1991 model year as a 454. There were 502 cu. in. versions, but never installed in a production vehicle, the 502s were over-the-parts-counter only. Changes to the Gen 5 as compared to the Mk IV included, but are not limited to: rear main seal (and therefore the crankshaft and block) were changed to accept a one-piece seal, oiling passages were moved, the mechanical fuel pump provisions were removed from the block casting, the machined boss for a clutch bracket was eliminated, the cylinder heads lost the ability to adjust the valve lash, and the coolant passages at the top of the cylinder block were revised. The changes to the coolant passage openings meant that installing Mk IV cylinder heads on a Gen 5 block could result in coolant seepage into the lifter valley. Frankly, the changes (except for the one-piece rear main seal) were all easily recognized as cost-cutting measures which also removed some quality and/or utility. All told, the Gen 5 engine was not well regarded by the Chevy enthusiasts because of the changes to the coolant passages and the lack of an adjustable valvetrain. As always, the aftermarket has provided reasonable fixes for the problems. The Gen 5 lasted only until 1995 Gen 6: GM recognized that it did not make any friends when it designed the Gen 5, and so they chose to revise the coolant passages again when designing the Gen 6, allowing the older heads to be used without coolant seepage problems. The boss for the clutch bracket returned, but was generally not drilled and tapped. The non-adjustable valvetrain remained, as did the one-piece rear main seal. Some but not all Gen 6 454 (and not 502) blocks regained a mechanical fuel pump provision. Production engines installed in pickup trucks got a high-efficiency cylinder head, still canted-valve, but with a modern heart-shaped combustion chamber of about 100cc. The intake port has a "ski jump" cast into it to promote swirling of the intake air flow. All production vehicles with a Gen 6 used a 454 version, but over-the-counter 502s are available. The Gen 6 is sometimes referred to as the "Gen Fix" because it fixed a number of issues that disappointed enthusiasts when the Gen 5 was released. As an added bonus, most if not all Gen 6 engines use hydraulic roller lifters.

    Gen 7: A very major revision of the previous engines resulted in the 8.1 liter/ 8100/ 496 cubic inch Gen 7 in 2001. The block gained .400 in deck height so it is the same height as the previous "Tall Deck" truck blocks, wider oil pan rails, and the cylinder heads have symmetrical port layouts instead of the previous 4 long/4 short port layout. Very little interchanges between the 8.1 liter engine and the previous Mark IV/Gen 5/Gen 6 engines. The head bolt pattern and even the firing order of the cylinders has been changed. There are some things that remained true to the previous Mk IV/Gen 5/Gen 6--the bellhousing bolt pattern, the side motor mount bolt pattern, the flywheel bolt pattern, and the exhaust manifold bolt pattern are the same. Note that the bolt holes are threaded for metric fasteners. The 8.1 is internally balanced, so you could install a flywheel/flexplate from a 396/427 Mk IV provided you use the correct bolts to suit the 8.1 crankshaft.

    I have had a chance to compare Mark IV, Gen 5/6 and Gen 7 head gaskets. It seems to be possible--but very difficult--to install IV/5/6 heads on the Gen 7 block. GM did this on one show vehicle, it IS possible. You must move three head bolt holes in the block; and as the holes only move about 1/2 their diameter it would be difficult to plug the existing holes, re-drill the new holes, and still have enough strength in the deck surface. There are cooling system differences as well that must be addressed. I have NOT done this conversion; but I do have comparison photos of the head gaskets.
    common BB CHEVY piston compression heights are
    1.270"
    1.395"
    1.520"
    1.645"
    1.765"
    remember the blocks deck height, minus the piston pin height minus 1/2 the crank stroke will equal the required connecting rod length
    OR
    the blocks deck height, minus the connecting rod length, minus 1/2 the crank stroke. will equal the required piston pin height
    yes its common for a combo to have the piston deck height located .010-.015 above or below the deck of the block so you'll need to select a head gasket thickness that compensates, too allow your engine to get a .038-.044 piston deck to cylinder head QUENCH DISTANCE.

    Specifications:
    (sorry if this table loses it's formatting: I don't know how to fix it. It looks "ok" at full screen width on my computer)

    Engine family Displacement Bore Stroke Rod length

    MK I 348 4.125 3.25 6.135

    MK I 409 4.31 3.5 6.010

    MK I 427 4.31 3.65 6.135

    MK II 427 4.31 3.65 6.135

    MK IV 366 3.938 3.76 6.135 (Only offered as a medium duty truck engine)

    MK IV 396 4.094 3.76 6.135

    MK IV 402 4.125 3.76 6.135

    MK IV 427 4.250 3.76 6.135 (Offered in passenger car and medium duty truck versions)

    MK IV/Gen 5/6 454 4.250 4.0 6.135

    MK IV 482 4.250 4.25 6.405 (very rare, made only for offshore boat races. Used tall-deck block)

    Gen 5/6 502 4.466 4.0 6.135 (Over the parts-counter only; not installed in production vehicles)

    Gen 7 496/8.1 4.25 4.37

    Specials: GM has sold many special-purpose engines, partial engines, blocks, cylinder heads, etc., "over the parts counter" that were never installed in production line vehicles. It is very difficult to track all the various items--suffice to say that heavy-duty "Bowtie" blocks and cylinder heads in various configurations--Mark IV, Gen 5, etc, have been produced. Oldsmobile used the Big Block Chevy as a baseline when designing the first of the Drag Race Competition Engines (DRCE) so that the early DRCE engines have an Olds Rocket emblem cast into the block, but it's Chevy parts that fit inside. There are special high performance blocks and heads, in either iron or aluminum, produced by GM and by aftermarket suppliers to suit almost any racing need.

    Coolant Routing Mk IV/Gen 5/Gen 6
    There are two different ways that coolant can be routed through the engine: series flow and parallel flow. Both ways work just fine. There may be a slight preference for parallel flow, but it is not a big deal. Series flow has the water exiting the water pump, flowing through the block to the rear, it then transfers through the head gasket and into the cylinder head through two large passages on each cylinder bank at the rear of the block. The coolant then travels from the rear of the head, forward to the front of the head, into the intake manifold water passage and out past the thermostat and thermostat housing. The water cools the block first, then it cools the head. The coldest water (coming out of the water pump) is directly below the hottest water (having already picked up the heat of the block and the head) as the hot water transfers into the intake manifold. By contrast, parallel flow has the water exiting from the water pump into the block, where a portion "geysers" up into the head between the first and second cylinder, another portion "geysers" up to the head between the second and third cylinders, another portion geysers up to the head between the third and fourth cylinder, and the remainder transfers to the head at the rear of the block. The coolant temperature inside the engine is more even that way. The differences in coolant routing is having (or not having) the three additional coolant transfer holes in each block deck, and three matching holes in the head gasket. The heads have passages for either system, and are not different based on coolant flow.

    Be aware that gaskets that DO have the three extra holes between the cylinders often have restricted coolant flow at the rear--instead of having two large coolant transfer holes at the rear, there is only one, and it's the smaller of the two holes that remains. This is important because if you use a parallel flow head gasket on a series flow block, you can have massive overheating and there's NOTHING that will cure the problem except to replace the head gaskets with ones that don't restrict flow at the rear of the block, or to drill the block decks to allow the coolant to flow into the head between the cylinders. Here's why they can overheat: A series-flow block doesn't have the openings between the cylinders, no coolant can flow up to the head there. The gasket may only have the single, smaller opening at the rear, so the amount of water that gets through that opening is greatly reduced from what the block designers intended. The result is that the coolant flow through the engine is only a fraction of what is needed.

    Most, but NOT all Mk IV engines are Series Flow. ALL Gen 5 and Gen 6 engines are Parallel Flow. A series flow block can be converted to parallel flow by drilling 3 holes in each deck surface, and then use parallel flow head gaskets. You can use the parallel flow gaskets as templates for locating the additional holes. It's really easy: Put the parallel flow gaskets on the block, mark the location and size of the three extra holes. Remove the gasket. Grab a 1/2" drill and a drill bit of the correct size, and pop the extra holes in the block. There is NO modification needed on the head castings. Some blocks have one of the holes already, but it needs to be ground oblong to properly match the gasket. Again, very easy with a hand held die grinder and rotary file.

    Chevy Performance BBC Bow Tie Race Engine Blocks | JEGS

    Cast Iron Bow Tie Race Block Technical Notes
    Precision CNC-machining means +/- 0.001'' tolerances
    Standard deck (9.800'') or tall deck (10.200'')
    4.240'' Finish Bore (4.600'' Maximum Bore, .250'' Minimum Wall Thickness)
    A sonic bore check data sheet is provided with each block
    Lifter bores are .300'' taller than standard blocks
    Siamese cylinder bores
    Improved cooling around number 1 cylinder
    Accepts Mark IV or Gen V, Gen VI cylinder heads
    Use Gen V head gaskets with Mark IV and Gen V cylinder heads
    Use Gen VI head gaskets with Gen VI cylinder heads
    Requires Mark IV design 2-piece rear main seal oil pans
    Requires Mark IV design crankshafts
    Can use Mark IV and Gen V, Gen VI camshafts, timing sets, lifters and timing cover
    (aftermarket belt drive timing covers may require clearancing)
    Blind-tapped head bolt holes; extra inner head bolt bosses provided
    4-bolt SAE 8620 main caps splayed 16° on the three center mains
    Priority main oiling wet sump system
    Provisions for dry sump oil line provided
    Honed camshaft and crankshaft bores
    0.842'' lifter bores (maximum 1.06'') may be relocated
    Distributor gear clearance at bottom of number 8 cylinder bore should be checked
    Machined mechanical fuel pump pad
    Tested to 1,200 horsepower!


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    Please check out my guides to GM small block engines , and Olds, Pontiac, and Buick big block engines, Mopar V-8 engine families, Ford V-8 engine families since 1932 or HEI distributors , too.
    INVESTING THE TIME AND EFFORT IN PURCHASING AND READING A FEW BOOKS WILL BE VERY COST EFFECTIVE
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    http://www.chevydiy.com/complete-history-chevy-big-block-engines/

    http://www.superchevy.com/how-to/4567-chevrolet-big-block-engine-generations/

    http://www.superchevy.com/how-to/project-cars/0704ch-chevy-big-block/

    http://www.dragzine.com/tech-stories/en ... ine-block/

    "http://garage.grumpysperformance.com/index.php?threads/building-a-tall-deck-bbc.188/#post-28633
    I came too the conclusion decades ago that if you want something, that look ,sounds, and performs impressively your rarely disappointed with a correctly built big block chevy.
    I build more BBC engine that almost all the rest combined and most are not all that radical, just street/strip muscle car engines, Id be happy to give you some insight and parts suggestions , I know you can build something that will provide the car with impressive performance yet still maintain a good deal of daily driver comfort, the extra displacement, better heads, bigger valves etc. do have marked advantages.

    bargain big block chevy heads, and some related info

    http://www.dragzine.com/tech-stories/engine/ultimate-guide-to-budget-bbc-cylinder-heads-under-2000/

    http://www.ohiocrank.com/chev_bb_shortb.html

    https://www.summitracing.com/parts/mll-bp4961/overview/

    http://www.blueprintengines.com/index.php/products/bp-shortblocks-landing/gm-496-stroker-sb-main

    http://www.superchevy.com/how-to/engines-drivetrain/sucp-0706-chevy-big-block-cylinder-heads/

    http://www.enginebuildermag.com/200...-cylinder-heads-for-streetstrip-applications/

    http://garage.grumpysperformance.com/index.php?threads/aftermarket-heads-for-a-bbc.12316/

    http://www.hotrod.com/articles/ccrp-0803-big-block-cylinder-heads/

    http://www.tristarengines.com/catal...-shortblock-featuring-darttm-big-m-block.html

    READ THIS THREAD
    http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/


    A fairly mild hydraulic roller cam like this
    http://www.claysmithcams.com/bbc-454-to-470-cid-old-school-oem-049-781-heads-to-a-max-of-5700-rpm/
    a decent set of heads, intake , road race oil pan, about 9.5:1-10:1 compression, and 600 ft lbs and 500 hp is easy
    https://www.summitracing.com/parts/edl-2095

    what your basically looking for can be easily provided with a set of decent quality oval port heads, a dual plane intake intake matched to a 454-496-540 big block (the larger the displacement the smoother the engine will run and the more massive the torque curve will tend to be, a 496 versions an excellent compromise) with a fairly mild hydraulic cam, and a 750cfm-850 cfm carb, and low restriction headers and exhaust, you'll be rather amazed at both the off idle torque yet docile ease of drive-ability and potential power available without needing the radical idle or need to build rpms before the car will pull briskly in traffic
    YOU KNOW YOU WANT THIS
    800 rpm idle, brisk acceleration, in traffic when you want it, you still have power brakes and
    a low rumble to the idle but no bad drive-ability issues,
    and you'll never need to break 5500 rpm,
    and rarely have any need to push past 3500 rpm in a daily comute
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    Im 68 years old and Ive been building and racing cars and engines since I was in my teens,Ive probably built an average of 3-4 BBC, and or SBC engines a year
    (with more than a few mopar, caddy, Buick, Pontiac engines along the way)
    mostly for the local muscle car guys and myself over the last 45 plus years and I can assure you both research and experience maters, I look back at what I built during my 20s and remember the frustration I felt not knowing what was required and thinking about all the mistakes I made back then I have constantly tried hard to help the newer guys avoid many of the pit-falls I learned from.

    yeah reading links sucks but it takes far less time and wastes FAR less money than blindly and randomly jumping into an engine build ignoring the potential problems and knowing what your doing and why and how its done never hurts
    http://garage.grumpysperformance.com/index.php?threads/hello-grumpyvette-here.278/

    http://garage.grumpysperformance.co...ting-started-in-the-car-hobby.339/#post-60187

    http://garage.grumpysperformance.co...gine-to-match-the-cam-specs.11764/#post-55651

    http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/#post-55314

    http://garage.grumpysperformance.co...-on-the-cheap-well-to-start.11739/#post-55365
     
    Last edited by a moderator: Nov 22, 2017 at 7:22 PM
  2. grumpyvette

    grumpyvette Administrator Staff Member

    if you thought that was good read thru this series
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    MARK VI BLOCK OIL CONNECTIONS
    http://www.idavette.net/hib/vette_bbfh.htm

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    and this article

    http://maliburacing.com/patrick_budd_article.htm

    more info

    http://www.circletrack.com/techarticles ... index.html

    before you spend a good deal of money porting and un-shrouding any iron cylinder heads, keep in mind aluminum heads are easily repaired in a skilled and experienced automotive machine shop thats equipped to do those repairs but damaged iron cylinder heads are either much harder to repair or good door stops
    http://garage.grumpysperformance.com/index.php?threads/iron-vs-aluminum-heads.389/#post-7266


    http://www.s-series.org/htm/tech/GMPerf ... 99-104.pdf
    http://www.superchevy.com/how-to/en...-big-block-casting-changes-through-the-years/
    Here’s a Look at the Various Chevy Big-Block Casting Changes Through the Years
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    With LS swaps all the rage these days, it’s easy to forget big-blocks are still alive and thriving. That’s because when it comes to making big power and even bigger torque, building it with a big-block is as easy as goading a smug Mustang driver into embarrassing himself at the stoplight.

    Most enthusiasts know the basic big-block cylinder block casting was updated in the 1980s, but fewer know General Motors quietly updated the basic design of the block casting only a few short years ago to give it greater strength, greater performance capability, and make common much of the differences between the early, Mark IV blocks and later, 1980’s-type Gen V castings.

    Big-block production engines were introduced, of course, in 1965 and remained in production with few changes for more than 20 years. Those are the Mark IV engines. In the late 1980s a new version arrived, designed primarily for marine and automotive fuel-injection applications. Those updated versions are referred to as the Gen V (and Gen VI) engines.

    Distinguishing between Mark IV and Gen V blocks is easy: if it has a mechanical fuel pump mounting pad, it’s a Mark IV. If there’s no fuel pump pad, it’s a Gen V block. There are several other differences—particularly in the water jackets near the deck surfaces—that make some Mark IV and Gen V parts non-interchangeable, including crucial components such as cylinder head gaskets.

    Within the last few years, General Motors revised the production-based big-block casting to accommodate features of the Mark IV and Gen V, enabling cylinder head and gasket interchangeability. It also features a mechanical fuel pump pad recast into the architecture. Other, less-visible changes to the basic casting include revised oiling to allow for larger camshaft bearings, thus higher camshaft lift. There has also been talk of creating extra clearance for roller timing chains, but as of our press deadline, that change hadn’t been implemented.

    The latest block design is available from Chevrolet Performance (chevrolet.com/performance) under part numbers 19170538 and 19170540. The “0538” version comes with 4.250-inch finished bores to support 427- and 454-cubic-inch engines, while the “0540” block has larger-diameter 4.470 bores to build a 502-inch engine. Each can be overbored for a larger displacement, with the 0540 block supporting up to 4.500-inch bores. Notably, all of Chevrolet Performance’s crate engines use the revised casting design.

    If you’re looking to build a mountain motor with an even larger bore, you’ll have to look at Chevrolet Performance’s Bowtie blocks, which support up to a 4.600-inch bore, or an aftermarket block.

    For strength and parts interchangeability, the big-block castings’ specific changes and updates include a slightly beefier main web on the 0538 block, while both versions have revised water jackets near the deck surfaces, allowing Mark IV or Gen V head gaskets to be used interchangeably. The front bulkhead is revised, too. It is thicker and stronger, with marked provisions for a 10-bolt timing cover. Actually, the bulkhead is drilled and tapped for a conventional six-bolt cover, while the remaining holes must be finished by drilling out the prescribed positions. There is more material around the lifter bosses and a revised rear-of-block section allows for the machining of one- or two-piece main seals (similar to the Gen V design).

    Oil pressure feed holes were added to the oil filter boss and front bulkhead to support oil feeds for superchargers, turbochargers, etc., while the oil hole next to the camshaft bore (at the front of the block) was repositioned to enable safe machining of the cam bore to accept a 50mm roller camshaft bearing. A new boss was added next to the distributor hole in the valley to support hardware for digital ignition equipment, and a front clutch boss has been added for older vehicle applications.

    Also, a pair of new core plugs was added to the rear bulkhead. Chevrolet Performance says they enhanced the manufacturing process at the foundry and help improve overall quality. Also, a “Bowtie” emblem and other identifying marks were added to the Bowtie block, distinguishing it from previous castings.

    In addition to the production-based “Mark”-type casting, Chevrolet Performance’s Bowtie block castings are designed for the highest-performance applications. They feature a few minor differences when compared with the Mark block, but include the common core’s updates for greater interchangeability. Most notably, the Bowtie blocks are machined for splayed main bearing cap bolts, whereas the “standard” versions feature production-style parallel main cap fasteners. The Bowtie blocks also have a distinctive water jacket design that allows the 4.600-inch bore capacity. There are seven part numbers offered for Bowtie blocks, some with the standard 9.800-inch deck height and one-piece rear main seal, and others with a tall, 10.200-inch deck height and two-piece rear main seal design.

    There you have it: The big-block is renewed and improved after more than 50 years of stalwart performance. The updates will keep big-block engines viable for the foreseeable future and continue to prove the adage that there’s simply no replacement for displacement.
    [​IMG]
    The latest big-block casting has undergone significant updates to align the differences that distinguished earlier Mark IV and later Gen V blocks, while also strengthening the block and adding provisions that support greater performance.
    [​IMG]

    The most noticeable visual change to the latest design is the reintroduction of a mechanical fuel pump mounting pad machined into the passenger-side front corner of the block. Gen V blocks did not have this provision.
    [​IMG]

    The front of the block was revamped for greater parts interchangeability with the Mark IV and Gen V, including using 6-bolt or 10-bolt timing chain covers. (It comes with the 6-bolt cover holes machined, but is easily drilled and tapped for the 10-bolt cover.) Also, a Bowtie-style auxiliary pressurized oil line hole is machined near the bottom of the China wall.
    [​IMG]
    A revised oiling design (the oil hole next to the cam bore was repositioned) allows the camshaft bore to support the 50mm bearing of a roller-style, high-lift camshaft.

    [​IMG]

    The valley is mostly unchanged, but is machined for a roller-type valvetrain with more material cast around the lifter bosses. Also, a bolt boss is added next to the distributor boss to support digital ignition systems.
    [​IMG]

    Deck height specs remain unchanged at 9.800 inches for production-based blocks, but the water jackets beneath them are revised so that early Mark IV-type and later, Gen V-type head gaskets can be used interchangeably. Some versions of the Bowtie block are offered with a 10.200-inch deck height.
    [​IMG]
    The rear of the block casting is updated with a common core that enables the machining of one-piece or two-piece rear seals. This permits the engine to be fitted with and dressed like an early Mark IV engine, albeit with the modern block casting.

    [​IMG]
    There are subtle changes to the interior bulkheads that incorporate the Bowtie design into 8.2L Mark blocks; the smaller-displacement 7.4L Mark block is unchanged, due to knock sensor accommodations. There are subtle machining updates, too.

    [​IMG]

    All Mark-type blocks—such as the one seen here—are manufactured with production-style parallel four-bolt main caps. The race-oriented Bowtie casting features splayed mains.
    [​IMG]
    The rear of the block features new plug holes, similar to what GM did with the small-block casting.

    [​IMG]
    A new hole (shown at the very bottom of the photo) is added to the oil filter boss on the block to support a pressurized oil feed.

    [​IMG]
    head bolts that show any thread damage should be replaced,
    and be aware that NEW ARP studs put far less sress on threads,and are potentially stronger, than using bolts to secure heads to the block

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    rectangle port heads generally work best on 500 or larger displacement engines
    with at least 10:1 compression and cams with at least 245 duration at .050 lift and valve lifts over .600 to take advantage of the potential port flow rates


    [​IMG]
    [​IMG]
    [​IMG]
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    [​IMG]

    RELATED THREADS YOU SHOULD READ
    http://garage.grumpysperformance.co...-peanut-port-big-block-combo.2900/#post-61085

    http://garage.grumpysperformance.com/index.php?threads/porting-can-help.462/page-3#post-59145

    http://garage.grumpysperformance.com/index.php?

    http://garage.grumpysperformance.co...gine-build-up-for-the-street.3153/#post-11626

    http://garage.grumpysperformance.co...tting-up-the-valve-train.181/page-2#post-7684

    http://garage.grumpysperformance.co...a-peanut-port-big-block-combo.2900/#post-7532

    http://garage.grumpysperformance.com/index.php?threads/cheaper-454-chevy-build.4620/#post-46849

    http://garage.grumpysperformance.co...at-angles-and-air-flow.8460/page-2#post-32923

    http://garage.grumpysperformance.co...olishing-combustion-chambers.2630/#post-50247

    http://garage.grumpysperformance.com/index.php?threads/bbc-intake-manifold-choices.12949/

    http://garage.grumpysperformance.co...ing-parts-and-a-logical-plan.7722/#post-57946

    http://garage.grumpysperformance.com/index.php?threads/multi-angle-valve-job-related.3143/

    Another major addition to the big-block casting is a clutch equalizer boss that makes the block a better fit for vintage muscle cars and their four-speed transmissions.
    IF YOUVE GOT DEEP pockets
    aluminum's FAR easier to repair once damaged as TIG welding ALUMINUM is far simpler than nickle brazing cast iron, aluminum dissipates heat faster, aluminum,s far easier to machine, and if your doing some mods you can weld stuff too aluminum far easier
    but the cast iron blocks USUALLY got an edge in stiffness
    the big problem is COST,

    http://www.brodix.com/blocks/5inchblock.html

    http://www.brodix.com/blocks/4.500block.html

    http://www.dartheads.com/products/engin ... ig-blocks/

    http://www.dartheads.com/products/engin ... locks.html

    http://garage.grumpysperformance.com/index.php?threads/picking-a-cam-for-street-strip-496-bbc.13384/

    http://www.cnblocks.com/

    http://www.lsmeng.com/Blocks.html

    http://garage.grumpysperformance.com/index.php?threads/building-a-tall-deck-bbc.188/#post-28633

    http://sdparts.com/details/gm-performan ... s/19170540

    http://www.jegs.com/p/World-Products/Wo ... 3/10002/-1

    http://garage.grumpysperformance.com/index.php?threads/magnets.120/#post-49772
     
    Last edited by a moderator: Oct 10, 2017
  3. brain55

    brain55 New Member

    I am currently having a Gen VII, 8.1L engine rebuilt for my 2001 K3500 GMC Sierra. I have learned a few things so far.

    First of all, even though this engine is 8 years old now, there are very few aftermarket parts available.

    One of the first things my machinist noticed was that it has low tension oil rings from the factory (which may explain the 2 qts. of oil it used every 3000 miles since the day I bought it).

    It has torque to yield head bolts which are not reusable (ARP is just now working on making bolts available for this) I'm hoping are are going to be available before my machinist needs them or I will be buying 2 sets of the factory bolts, since this engine has to be bored with torque plates. We had to buy factory rod bolts, ARP doesn't make these yet either.

    The rockers on these heads are not adjustable. ARP does make rocker studs with the correct metric threads so I am going to upgrade to full roller rockers and they will be adjustable too. Crower is going to regrind a cam for me to get some added bottom end torque.

    I expect to be towing a 14,000+ lb trailer daily with this truck, which is why I choose the have an engine built for it after 165,000 miles. I will update this with more info as I get it.

    Brian
     
  4. grumpyvette

    grumpyvette Administrator Staff Member

    thanks for posting that info,
    and please keep us up to date on your progress, and any part numbers for components as you find them.

    http://garage.grumpysperformance.co...ng-piston-pin-height-compression-height.5064/

    http://garage.grumpysperformance.co...n-wrist-pins-one-really-over-looked-part.978/

    http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/


    if you find the rotating assembly is more difficult to rotate than you expected, you may want to verify some clearance issues that get over looked at times,
    theres also some, other potential issues,
    theres a slight potential for the piston wrist pins too not rotate effortlessly in the piston pin bores ,

    that may add to the difficulty in rotating the assembly in the block.
    the piston rings must have vertical and back clearance in the piston ring grooves

    [​IMG]

    [​IMG]

    [​IMG]
    Piston Ring Groove Clearance
    Pistons are grooved to fit rings that seal the cylinder’s compression and allow for lubrication of the cylinder walls. Piston rings come in a set. There are two compression rings. The top ring is affected by the most cylinder compression pressures. The second compression ring reinforces the top ring. The third ring down is the oil ring. It controls lubrication between the piston and cylinder bore.

    [​IMG]
    Place the new ring into the top piston groove, and then place a feeler gauge into the gap between the new ring and the upper land. Move around the pistons groove and obtain a few measurements. Compare this reading to specifications. If this reading is too much and the gap is too large, the piston must be replaced. The top ring takes the most compression. This causes the ring to slap against and wear the lands in the piston groove.
    [​IMG]

    [​IMG]

    [​IMG]

    and of course the pistons must have the correct piston too bore clearance. and connecting rod can only be installed facing one direction
    [​IMG]
    [​IMG]
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    [​IMG]
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    [​IMG]

    Last edited: Today at 3:38 PM


    [​IMG]
    BTW when you go to buy a ring compressor....this type(ABOVE & BELOW) works far better than the others, but its specific to a very limited range in bore size applications

    [​IMG]

    http://store.summitracing.com/partdetail.asp?autofilter=1&part=PRO-66766&N=700+115&autoview=sku

    Proform 66766 $31

    remember to dip the piston and rings in high quality oil just prior too or before assembly I,ve used MARVEL MYSTERY OIL FOR DECADES
    [​IMG]
    [​IMG]
    [​IMG]

    this style ring compressor below has a nasty habit of not keeping the rings evenly compressed and not seating evenly on the block , Ive used them but the type above is much easier to use
    [​IMG]
     
    Last edited by a moderator: Oct 23, 2017
  5. brain55

    brain55 New Member

    Just a quick update.

    My original plan was to have a core rebuilt and then just do an engine swap, in-out-no problem. Well, as I am learning with this engine, nothing is easy. My engine builder's core supplier went through 5 blocks and was not able to come up with a good block. So plan B, I took my truck over to a shop he recommended to pull my engine so he would have something to rebuild. As expected he was able to see that the 2 qts of oil this thing burned every 3000 miles went right past the rings. The piston tops and combustion chambers were completely gooey with oil.

    The one good thing so far is that the bore will clean up at .020" oversize. That brings us back to the next ordeal. Nobody makes a standard tension oil ring for this engine. So we sent the pistons to Total Seal today so they could cut 3/16" oil ring grooves in them instead of the 4mm stock width. So we should get those back next week and then he can send everything off to the balancers.

    In the mean time he can work on the heads. I hope that that goes smoothly. We ordered ARP's screw in rocker studs with the correct metric threads for the head and Comp Pro-Magnum full roller rockers so I will have adjustable valvetrain now. I hope GM didn't do anything screwy with the rocker geometry and standard 1.7:1 rockers will work.

    When this is all said and done I will post part numbers. I don't want to put anything down untill I know its going to work.

    Brian
     
  6. grumpyvette

    grumpyvette Administrator Staff Member

    related links with lots of info


    http://www.chevyhiperformance.com/techa ... index.html

    http://reviews.ebay.com/Big-Block-Chevy ... 0001563647

    viewtopic.php?f=51&t=2692


    http://www.carquest.com/common/download ... 3_4886.pdf

    Issue:
    General Motors (GM) 7.4L (454 CID)
    engines use two types of engine
    blocks: the Mark IV and Mark V. The
    Mark IV is found on 7.4L engines in
    model years from 1965 - 1990, and
    the Mark V is found on 7.4L engines
    in model years from 1991 and later.
    Often, installers will attempt to adapt a Mark IV cylinder head for a Mark V block.
    This conversion can be made if attention is paid to the coolant circulation because
    the Mark IV and Mark V have different coolant flows, and were
    originally designed for different head gaskets. If the conversion is not performed
    correctly, the engine will overheat, causing premature engine wear and damage.

    Resolution:
    CARQUEST Gaskets by Victor Reinz® has designed two Nitroseal® head gaskets
    to specifically allow for this conversion. The installation requires that CARQUEST
    Gaskets by Victor Reinz® part number 4918 be installed on the right cylinder
    bank to maintain proper coolant circulation, and part number 4923 be installed on
    the left cylinder bank
    for the correct coolant flow.

    Application:
    Ask for CARQUEST Gaskets by Victor Reinz® part numbers 4918 (right bank)
    and 4923 (left bank), or part number 4886 for conventional Mark V applications
    and part number 3884SG for conventional Mark IV applications.
     
  7. grumpyvette

    grumpyvette Administrator Staff Member

    Big Block Chevrolet Gen V and Gen VI Oiling SystemSolving the mystery of the Gen V and Gen VI Priority Main Oiling system
    Priority Main Oiling System
    The Generation V and VI big block Chevrolet blocks feature a priority main oiling system where the main oil supply passage is located adjacent to the camshaft tunnel. Drilled passages which intersect this large oil tunnel carry oil directly to the main bearings. If you are facing the front of the block with the engine in the upright position, this main oil supply tunnel is located in the 2 o’clock position just below the right hand lifter oil supply line.

    Oil Cooler Plumbing
    Located along the oil pan rail just ahead of the oil filter pad are two drilled and tapped (3/8” NPT) oil passages for routing oil to an external oil cooler. The hole located closest to the oil filter pad (#2) is for the outgoing supply line to the oil cooler. The front passage (#1), which is farthest from the filter pad, is the return line from the oil cooler.

    Careful examination reveals that these two passages intersect the same return line that feeds oil back to the main oil tunnel. This requires that a special fitting be used in the #2 supply line to prevent oil from short circuiting the oil cooler.

    Part number SD1540 provides the necessary diverter basket to prevent the supply oil from entering the return line before going to the oil cooler. This fitting has a dash 10AN thread to allow the use of aftermarket components to plumb your external oil cooler. The front passage #1 will require a 3/8” NPT by dash 10AN adapter (#FCM2185), which is available from Scoggin-Dickey.

    Understanding By-pass Valve Locations
    Factory assembled 454, 502 engines and short blocks have two by-pass valves installed in the block. These factory installed by-pass valves (#25013759) will open at an 11 psi pressure differential. One by-pass valve is installed in the center hole on the oil filter pad (#4). This hole is the oil return passage from the oil filter. The second by-pass valve is installed in the adjacent hole (#3). The egg shaped hole (#5) is the high pressure oil supply passage from the oil pump.

    For all racing application that will NOT use an oil cooler but will maintain the stock oil filter location, you must remove the center by-pass valve in location #4. Removing this valve eliminates three redundant right runs in the oil system. However, if you leave this by-pass in place the oil system will still function as it was intended, but a loss of oil pressure can result from the four right angle turns required for oil to return to the main oil tunnel.

    If you intend to use a remote oil filter, a high pressure by-pass valve part number 25161284 must be installed in position #3. This valve will open at a 30 psi pressure differential. A plug will be installed in position #4 to prevent oil flow thru this passage. Oil should be returned to the block in the 3/8” hole located just able the oil filter pad. An oil filter block off plate kit (#SD3891) can be purchased from Scoggin-Dickey for Gen V and VI blocks to plumb your external oil filter.

    If you intend to maintain the stock filter location and will use the factory provided oil cooler passages to install your oil cooler, then you must install two high pressure by-pass valves (#25161284). One will be installed in location #3 and the second in location #4. Happy oiling!
     
  8. grumpyvette

    grumpyvette Administrator Staff Member

    By David Reher-Morrison Racing Engines

    The road to high technology is often a two-way street. People who are involved in motorsports maintain that racing improves the breed, from the invention of the rearview mirror by Ray Harroun, the first Indianapolis 500 winner, to the disc brakes and low-profile tires that are commonplace on cars today. But the improvements that are made on everyday automobiles and trucks can pay dividends for racers, too. The extended lifter bosses in the sixth-generation (Gen VI) big-block Chevrolet V8 are an example of production engine technology that has benefited hardcore drag racers.
    http://www.cranecams.com/userfiles/PP0811A_SinglePages.pdf
    GM engineers lengthened the lifter bosses in late-model small-block and big-block V8 engines to accommodate hydraulic roller lifters. The switch from flat tappets to roller lifters was primarily intended to reduce friction and to improve fuel economy on the highway. It had the additional benefit of allowing faster, more aggressive camshaft profiles that boosted horsepower in high-performance street engines like the LT1 and LT4 small-blocks.

    When the first Gen VI big-block with tall lifter bosses arrived in our shop, we were dismayed. There weren’t any commercially available solid roller lifters that would fit the extended bores. Our first impulse was to machine the tops of the bosses to accept the shorter lifters we’d used for years, but then we realized that would be a big step backward. We recognized that the longer bosses would stabilize the lifters in their bores – a real advantage in big-block Chevy engines with angled pushrods.

    Crower stepped up with a redesigned roller tappet with a longer body and a raised tie bar that cleared the taller lifter bosses. Now “long body” lifters are available from many performance camshaft companies.

    When we overhauled the first race engines built with Gen VI blocks, we discovered that lifter bore wear was dramatically reduced. With the old short lifter bosses, the tops of the bores were often bellmouthed after a season of racing. That’s because the big-block Chevy’s sharply angled pushrods subject the lifters to strong side loads. This sideways thrust is especially apparent in engines with Dart Big Chief and Brodix Big Duke spread-port cylinder heads because they have more severe pushrod angles than conventional siamesed port heads.

    When Richard Maskin was developing the aftermarket Dart Big M big-block, I recommended that he use extended lifter bosses because of our positive results with this design. In fact, we now use Big M blocks with tall lifter bosses for almost all of our Super Series engines. I was surprised to learn recently that Dart also offers Big M blocks with the lifter bosses machined down to standard height. When I quizzed Maskin about this, he told me that many racers still want to use their old short-body lifters.

    In my opinion, short lifters are the wrong approach. If a racer is going to spend the money on a brand-new block, he should take advantage of the latest technology that’s available. Yes, a set of long-body lifters costs more than a set of standard lifters, but the benefits they offer in longer service life and improved reliability are well worth the relatively minor additional expense. It’s false economy to save a few dollars on lifters when you consider the thousands it can cost to repair an engine after a catastrophic lifter failure.

    There are also instances in engine design when the racers have the right idea. One of the major shortcomings of the production big-block Chevrolet V8 is its four “missing” head bolts on the intake side of cylinders No. 2, 3, 6 and 7. While the other four cylinders have six head bolts arranged symmetrically around each bore, there is a 4.550-inch span between the upper head bolt holes on these four cylinders which have only five fasteners. Since the four missing bolt holes would be located underneath the intake ports in a stock big-block head, I can only assume that these bolts were eliminated because of the difficulty of installing them on an assembly line and servicing the cylinder heads in the field.

    When the first aluminum versions of the Chevy big-block V8 were released for Can-Am road racing in the late ’60s, they featured four bolt bosses in the lifter valley. These bosses engaged studs or bolts that threaded into holes underneath the intake ports to provide the clamping force that is required to seal the head gaskets in a competition engine. Today most big-block cylinder heads have provisions for these studs, even if the bosses aren’t drilled and tapped.

    Unfortunately, these lifter valley head bolt bosses were never incorporated in production cast-iron blocks. When we built our first big-block racing engines with Mark IV blocks, we dimpled the deck surfaces with a centerpunch in an attempt to hold the gasket in place. Later we fabricated steel head lugs and mounted them in the lifter valley with bolts and dowel pins. The first option really wasn’t very effective, and the second was expensive and time-consuming.

    We see evidence of seepage past the head gaskets in almost every competition big-block Chevy V8 that does not have these four additional head fasteners. When the power level reaches 850 to 900 horsepower, the head gaskets are almost certain to fail in the long span between the upper head bolts.

    In the past, the most practical solution was to machine the block for O-rings and use soft copper head gaskets. This is an expensive proposition, however, when your goal is to build affordable engines for sportsman racers. Fortunately, GM’s CNC-machined Gen VI competition cylinder case, some Merlin blocks and all Dart Big M blocks now incorporate head bolt lugs in their lifter valleys – a real improvement over production castings. Among these alternatives, the Big M block is the most affordable choice for sportsman racers.

    It doesn’t take much clamping force to solve the big-block’s head gasket problems. We use a 3/8-inch stud torqued to 45 ft./lbs. on our Super Series engines. This has proven to be so effective that we have eliminated O-rings on all but our most powerful big-block bracket engines.

    There is a common misconception that more torque on the head fasteners improves head gasket sealing. We use imprint paper to measure the load on the head gaskets, and we have learned that less is better in many instances. The length of the fasteners (bolts or studs) and the distance between them affects the clamping force they produce on the gasket. On our Pro Stock DRCE engines, for example, we torque the outer row of studs to 55 ft./lbs., the valley bolts to 42 ft./lbs. and the long center studs to 70 ft./lbs. We have found that these different torque specifications produce the most uniform loads on the head gasket and keep the head as flat as possible on the block’s deck surface.

    Racing is about finding solutions to problems, whether it’s seeing the guy behind you with a rearview mirror or keeping the lifters and head gaskets alive in a big-block V8. In most instances, it’s not rocket science, but simply common sense.
    Share this:
     
    Last edited by a moderator: May 7, 2017
  9. grumpyvette

    grumpyvette Administrator Staff Member

    By David Reher, Reher-Morrison Racing Engines

    “There are some basic skills that must be mastered to build an engine successfully.”

    I traveled backward in time last week. It happened while we were rebuilding a big-block Chevrolet engine. This particular engine won the 1982 NHRA Pro Stock championship, and overhauling it was like firing up a time machine.

    We’re creating a replica of the championship-winning Reher-Morrison Camaro that will be displayed in the Hendrick Motorsports museum in Concord, N.C. I consider it an honor to have one of our race cars alongside Rick Hendrick’s stable of NASCAR champions. We’re out front with the fact that it’s not the real car – the original is under the care of a collector in West Texas – but the motor is the real deal.

    In its time, this was the baddest big-block Chevy in the country. Today there are better parts and more advanced technology in just about any bracket racing engine we build at Reher-Morrison.

    I’m looking at this killer engine from 1982, and shaking my head. The genuine GM aluminum cylinder heads still have “X” marks on the castings that signify they were made with cores we’d shaved at the Winters foundry. It’s got stock-diameter lifters, without a lifter bushing in sight. Aluminum rods as big as clubs, stud-mounted rocker arms, and spindly pushrods – that was the state of the art 28 years ago.

    Seeing an artifact like that 1982 Pro Stock engine reinforces my belief that we are currently living in the Golden Age of engine development. Many of today’s off-the-shelf parts are superior to the handmade, high-dollar, top-secret components that powered yesterday’s record-setting Pro Stocks. In fact, I sometimes fantasize about racing one of our Super Series sportsman engines back in the day when the Reher-Morrison Chevrolets were battling Glidden, Johnson, and Iaconio for the top spot in Pro Stock. I think it would have been a powerful weapon.

    My intention is not to wallow in nostalgia, but to point out the strides in materials and technology made by aftermarket manufacturers. There is a multitude of aftermarket blocks available in a variety of configurations. If a customer wants a block with a 55mm cam, I can order one from the manufacturer instead of boring out the cam tunnel on a mill in our shop. If a racer wants cylinder heads with a 14-degree valve angle, I can get them with a phone call instead of spending days building up the decks with aluminum welding rod. Life is definitely good for racers and engine builders these days.

    Unfortunately the law of unintended consequences hasn’t been repealed, and there is a downside to this rich bounty of parts. As always, the devil is in the details. With so many manufacturers producing so many variations, finding compatible parts can be extremely difficult for do-it-yourself engine builders. Just consider the myriad differences among “conventional” big-block Chevy cylinder heads in valve diameters, valve angles, guide locations, and combustion chamber shapes. A piston dome that fits one head perfectly can be a total disaster with another head. The height of the valve seats, the location and depth of the valve reliefs, the profile of the dome, the lift and duration of the camshaft, the rocker arm ratio, and a dozen other design features all must be considered.

    I’m told that GM has produced more than 95 million small-block V-8 engines. Replacement parts are available from any well-stocked dealership or auto parts store, and there is a reasonable expectation that every part will fit every engine. The market for specialized racing components is tiny in comparison, with no standardization among the various aftermarket manufacturers. Every manufacturer has a notion about how to make better parts – that’s what drives the performance industry. With this continuous development, it’s up to the engine builder to make sure that the parts will work together.

    Building an engine is an enjoyable and rewarding experience for many racers. That’s how I got started in racing, and I’m grateful that eventually it became my livelihood. But for some people, engine building is an exercise in frustration.

    I believe there are some basic skills that must be mastered to build an engine successfully. These include the ability to degree a camshaft, check piston-to-valve clearance, locate valve notches, measure valve angles, verify dome-to-head clearance, and align the intake manifold runners. There is no lack of information on these topics: Books and videos are available that describe these procedures in detail, and several schools teach the fundamentals of building racing engines.

    High-tech parts can be enticing, but a successful engine builder doesn’t overlook the basics. For example, when you’re building for maximum power, compression ratio matters. Piston-to-valve clearance is a major factor in determining compression ratio because the valve pockets are typically the largest surfaces on the piston dome. If the valve reliefs are deeper than necessary, it’s easy to give up 10cc or more of dome volume. That can mean the difference between a 15:1 compression ratio and a 13:1 compression ratio – and two full points of compression will have a huge impact on performance.

    What good is a set of the latest high-dollar CNC-ported cylinder heads if the compression ratio is under par? Few racers have the equipment and expertise to test cylinder heads, but anyone can check the compression ratio with a burette and a piece of Plexiglas. It’s a basic skill of engine building.

    I’m continually amazed at the subtleties of engine building. Just changing from one brand of lifters to another brand can change the engine’s oil pressure by eight or 10 psi. How is this possible? Take a close look at the oil grooves in the lifters. An annular groove acts like a restrictor to reduce flow through the oil gallery; a straight hole allows more oil to move through the lifter body and consequently reduces oil pressure. An inexperienced engine builder would be looking at the oil pump to fix a problem that’s really caused by a difference in lifter designs. That’s just one example of the complexities of a racing engine that’s assembled with parts from dozens of suppliers.

    Looking at the parts and pieces from that 1982 Pro Stock engine, it’s apparent that we didn’t know what we didn’t know. If we had understood the importance of valvetrain dynamics, the performance benefits of lightweight parts, and the impact of combustion chamber design, our engine would have been much different. We simply didn’t have the parts and the knowledge to build a more powerful engine; we did the best we could with what we had to work with.

    The evolution of engine technology never stops. I’m sure that 30 years from now, some builder will tear down a 2010 Pro Stock engine and wonder, “What were they thinking?”
    Share this:
     
  10. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    http://www.bhjproducts.com/bhj_downloads/techarticles/BHJ_LifterTru_MPCHB.pdf
    http://www.bhjproducts.com/bhj_content/products/blueprintfixt/ltk.php

    When the Mark IV was installed in production vehicles for the first time in 1965, it carried the Turbo-Jet name on the air cleaner, displaced 396 cubic inches, and was rated at a maximum of 425 horsepower in the Corvettes.

    Here’s a quick look at milestones in the big-block’s expanding and contracting history of displacement:

    396 cid – introduced in 1965, with 4.094-in. x 3.760-in. bore and stroke (first production Mark IV engine).

    427 cid – introduced in 1966, with 4.250-in. x 3.760-in. bore and stroke (aluminum versions used in COPO supercars).

    366 cid – introduced in 1968, with 3.935-in. x 3.760-in. bore and stroke (tall-deck; used in truck applications).

    402 cid – introduced in 1970, with 4.125-in. x 3.760-in. bore and stroke (advertised as 396 cid).

    454 cid – introduced in 1970, with 4.250-in. x 4.000-in. bore and stroke.

    502 cid – introduced in 1988, with 4.466-in. x 4.000-in. bore and stroke (Gen V block, originally developed for non-automotive applications; adapted later by Chevrolet Performance).

    572 cid – introduced in 2003, with 4.560-in. x 4.375-in. bore and stroke (developed by Chevrolet Performance; no production vehicle applications).
    [​IMG]
    its almost a standard up-grade at this point to index lifter bores and in many cases to use the larger diam. chrysler lifters,
    as they allow a larger and significantly stronger lifter roller wheel diam. or a more durable flat tappet to cam lobe wear surface
    chevy lifters are .842 while chryslers are .904
    [​IMG]
    [​IMG]
    [​IMG]

    but if your willing to pay for special cams and insert solid flat tappet lifters from the cam tunnel , or botton crank case side of the block while its inverted on the engine stand before the cam shaft is inserted holding them in the lifter bores, you can use mushroom base race lifters in a chevy, this allows you to gain the benefits of the larger chrysler lifter diameter while maintaining the stock lifter bore size, but its generally only done on race engines that see frequent maintence tear downs for inspection.
    [​IMG]
    [​IMG]

    [​IMG]

    [​IMG] [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]




    The common mushroom is .970", which is (pure coincidence, right?) Ford Model T IIRC.
    To calculate maximum velocity (lift in inches per degree of rotation): lifter surface - .040" for safety (.020" away from each edge to allow for tappet bank errors, etc. per Harold) ÷ 114.6.

    For various common tappets:
    .842" .00700”/deg.
    .875" .00729”/deg.
    .904" .00754”/deg.
    .921" .00769”/deg.
    .970" .00812”/deg
     
    Last edited: Feb 22, 2016
  11. 87vette81big

    87vette81big Guest

    I will read when I get home Grumpy
     
  12. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    I get calls asking for a bit of advice, all the time and I have built a good reputation among a group of the older local guys building engines , and for doing race car mods,for a rather select crowd , Im always amazed at the number of times I see guys who jump into projects without doing a moments research into the car they just purchased or parts availability or even if the car they bought is in decent mechanical or cosmetic condition,now we all start out that way but after being "burnt" a few times you might think that we would gain some experience and learn to "look before you leap"
    you might be astounded at the number of times that asking a few questions or putting a car up on a lift and doing a detailed inspection, or doing 30 minutes research into casting numbers could result in your having a far FAR better idea as to what your looking at, and what might be required in the process of that cars restoration, etc.
    and buying a shop manual and joining a couple local muscle car or corvette clubs along with spending time on the internet forums can do wonders to your skill set, but finding a couple older mentors or friends can be a huge help.
    all Im suggesting is that NO ONE person comes close to having all the skills and knowledge required in this hobby so stepping back and thinking things through and accessing several resources makes a great deal of sense as does being rather selective in your choices so you don,t waste time or money.

    I can supply a few tips ,and bits of info for anyone willing to jump down the rabbit hole, when your looking to machine cylinder heads for different valve springs, keep in mind your machinist needs to be careful as enlarging or deepening the valve seat depth and diameter, if done too much weakens the heads and installing stronger valve spring load rates adds considerable stress, so its possible to run into problems rather easily , if machine work is too extensive, ID suggest calling the cylinder head manufacturer for info on that! along with having a discussion with your machine shop.

    manufacturers can supply info , similar too but not limited too info ,like this
    that DIFFERS with each head design.so don,t blindly start machining heads for larger springs with higher load rates , ask and get the CORRECT answers first!
    [​IMG]


    http://garage.grumpysperformance.co...-the-rabbit-hole-with-alice.10933/#post-66925




    http://garage.grumpysperformance.com/index.php?threads/valve-springs.9613/#post-50556

    http://garage.grumpysperformance.com/index.php?threads/two-loose-valve-locks.9687/#post-36006

    http://garage.grumpysperformance.co...oper-valve-spring-seats-shims.1005/#post-1818

    http://garage.grumpysperformance.co...-loads-and-installed-height.10709/#post-46658

    http://garage.grumpysperformance.co...e-springs-and-setting-up-the-valve-train.181/

    http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/

    http://garage.grumpysperformance.co...d-high-spring-pressures-don-t-work-well.1489/

    http://garage.grumpysperformance.co...ring-installation-questions.12833/#post-66431

    http://garage.grumpysperformance.com/index.php?threads/what-springs.11352/#post-51835

    http://garage.grumpysperformance.co...train-clearances-and-problems.528/#post-46440

    http://garage.grumpysperformance.com/index.php?threads/removing-valve-seals.4283/#post-44287

    http://garage.grumpysperformance.co...lve-seat-angles-and-air-flow.8460/#post-29682

    http://garage.grumpysperformance.co...ide-issue-on-new-crate-motor.7979/#post-27508

    http://garage.grumpysperformance.com/index.php?threads/valve-spring-installation-questions.12833/

    http://garage.grumpysperformance.com/index.php?threads/busted-valve-spring.7716/#post-29797

    http://garage.grumpysperformance.com/index.php?threads/testing-valve-springs.1751/#post-4387

    Number Details
    10051107 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454, 4 bolt, Bowtie, MkIV, 9.8 deck, siamesed bores, 4.25-4.50 bore
    10069282 Category: Engine Blocks
    Type: Big Block V8
    Date: 1990-1991
    Notes: 366 tall deck, 4 bolt, Mark IV, Tall deck
    10069284 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 427 tall deck, 4 bolt, Mark IV, Tall deck
    10069286 Category: Engine Blocks
    Type: Big Block V8
    Date: 1990-1991
    Notes: 454, 4 bolt, Mark IV, Short deck
    10114182 Category: Engine Blocks
    Type: Big Block V8
    Date: 1991+
    Notes: 454, 4 bolt, Generation V
    10114183 Category: Engine Blocks
    Type: Big Block V8
    Date: 1991+
    Notes: 366 tall deck, 4 bolt, Generation V
    10114184 Category: Engine Blocks
    Type: Big Block V8
    Date: 1991+
    Notes: 427 tall deck, 4 bolt, Generation V
    10134366 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454 tall deck, 4 bolt, Bowtie, Generation V, Tall deck
    10185050 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454, 4 bolt, Bowtie, Generation V, Short deck
    10237297 Category: Engine Blocks
    Type: Big Block V8
    Date: 1996+
    Notes: 454, 4 bolt, Vortec 7400, L-29 Generation VI
    10237299 Category: Engine Blocks
    Type: Big Block V8
    Date: 1996+
    Notes: 427 tall deck, 4 bolt, Generation VI, 7.0L, truck
    10237300 Category: Engine Blocks
    Type: Big Block V8
    Date: 1996+
    Notes: 502, 4 bolt, Generation VI, 4.466 bore
    12550312 Category: Engine Blocks
    Type: Big Block V8
    Date: 1996+
    Notes: 427 tall deck, 4 bolt, Generation VI, 4.250 bore, fuel pump boss, clutch linkage pivot boss
    12550313 Category: Engine Blocks
    Type: Big Block V8
    Date: 1991+
    Notes: 454, 4 bolt, Generation V crate motor, Generation VI 4.25 bare block, fuel pump boss
    12556110 Category: Engine Blocks
    Type: Big Block V8
    Date: 2001+
    Notes: 496, 4 bolt, Generation VII 8.1L, Vortec 8100, Truck
    12561357 Category: Engine Blocks
    Type: Big Block V8
    Date: 1996+
    Notes: 454, 4 bolt, Generation VI
    12561358 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 502, 4 bolt, Generation VI
    14015443 Category: Engine Blocks
    Type: Big Block V8
    Date: 1987-1990
    Notes: 454, 2 or 4 bolt, Mark IV, Truck or Motorhome
    14015445 Category: Engine Blocks
    Type: Big Block V8
    Date: 1978-1990
    Notes: 454, 2 bolt or 4 bolt
    14044807 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454 tall deck, 4 bolt, Bowtie, MkIV, CNC prep, Tall deck, 4.25 bore or 4.495 bores
    14096859 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 502, 4 bolt, Generation V, HO
    24502504 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454, 4 bolt, Bowtie, Generation V, Race prep, 9.8 short deck height
    24502506 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 454 tall deck, 4 bolt, Bowtie, Generation V, Race prep, 10.2 tall deck height
    24502572 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 4 bolt, 4.5 bore Olds DRCE 2, 9.5 deck height
    25534402 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 4 bolt, 4.590 bore Olds DRCE 3, 9.25 deck height


    Number Details
    326711 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 4 bolt, aluminum, CanAm, 4.44 bores, steel cylinder liners
    340220 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1985
    Notes: 427 tall deck, 4 bolt
    345014 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1986
    Notes: 454,
    346236 Category: Engine Blocks
    Type: Big Block V8
    Date: 1975-1976
    Notes: 454, 2 bolt
    359070 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1990
    Notes: 454,
    361959 Category: Engine Blocks
    Type: Big Block V8
    Date: 1973-1990
    Notes: 454, 2 bolt or 4 bolt
    364776 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1985
    Notes: 427 tall deck, 4 bolt
    364779 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1990
    Notes: 366 tall deck, 4 bolt
    3782870 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1976
    Notes: 427 tall deck, 4 bolt
    3824553 Category: Engine Blocks
    Type: Big Block V8
    Date: 1966-1967
    Notes: 366 tall deck, 4 bolt
    3855961 Category: Engine Blocks
    Type: Big Block V8
    Date: 1965-1966
    Notes: 396, 2 bolt or 4 bolt
    3855961 Category: Engine Blocks
    Type: Big Block V8
    Date: 1966
    Notes: 427, 2 bolt
    3855962 Category: Engine Blocks
    Type: Big Block V8
    Date: 1965-1966
    Notes: 396, 4 bolt
    3855977 Category: Engine Blocks
    Type: Big Block V8
    Date: 1966-1973
    Notes: 366 tall deck, 4 bolt
    3869942 Category: Engine Blocks
    Type: Big Block V8
    Date: 1966-1967
    Notes: 427, 2 bolt or 4 bolt
    3902406 Category: Engine Blocks
    Type: Big Block V8
    Date: 1967
    Notes: 396, 2 bolt or 4 bolt
    3904351 Category: Engine Blocks
    Type: Big Block V8
    Date: 1967
    Notes: 427, 2 bolt or 4 bolt
    3904354 Category: Engine Blocks
    Type: Big Block V8
    Date: 1966-1976
    Notes: 366 tall deck, 4 bolt
    3916319 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968
    Notes: 366 tall deck, 4 bolt
    3916321 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968
    Notes: 427, 2 bolt or 4 bolt
    3916323 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968
    Notes: 396, 2 bolt or 4 bolt
    3925521 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1985
    Notes: 427 tall deck, 4 bolt
    3935439 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1969
    Notes: 427, 2 bolt or 4 bolt
    3935440 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1969
    Notes: 396, 2 bolt or 4 bolt
    3937724 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1985
    Notes: 366 tall deck, 4 bolt

    Number Details
    3937726 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1984
    Notes: 427 tall deck, 4 bolt
    3946052 Category: Engine Blocks
    Type: Big Block V8
    Date: 1969
    Notes: 427, 4 bolt, aluminum ZL-1, Mark IV
    3946053 Category: Engine Blocks
    Type: Big Block V8
    Date: 1997+
    Notes: 427, 4 bolt, aluminum ZL-1, 2nd version, Mark IV
    3955270 Category: Engine Blocks
    Type: Big Block V8
    Date: 1969
    Notes: 427, 2 bolt or 4 bolt
    3955272 Category: Engine Blocks
    Type: Big Block V8
    Date: 1969
    Notes: 396, 2 bolt or 4 bolt
    3955274 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1985
    Notes: 366 tall deck, 4 bolt
    3955276 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1973
    Notes: 427 tall deck, 4 bolt
    3963512 Category: Engine Blocks
    Type: Big Block V8
    Date: 1969
    Notes: 427, 2 bolt or 4 bolt
    3963512 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1976
    Notes: 454, 2 bolt or 4 bolt
    3969852 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1984
    Notes: 366 tall deck, 4 bolt
    3969854 Category: Engine Blocks
    Type: Big Block V8
    Date: 1969
    Notes: 396, 2 bolt or 4 bolt
    3969854 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1972
    Notes: 402, 2 bolt or 4 bolt
    3969858 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1984
    Notes: 427 tall deck, 4 bolt
    399204 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1971
    Notes: 509, 4 bolt, aluminum, CanAm, 4.5 bores, steel Cylinder liners
    399293 Category: Engine Blocks
    Type: Big Block V8
    Date: 1977-1978
    Notes: 366 tall deck, 4 bolt
    3999289 Category: Engine Blocks
    Type: Big Block V8
    Date: 1971-1979
    Notes: 454, 2 bolt or 4 bolt, some CE replacement blocks had four bolt main caps
    3999290 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1969
    Notes: 396, 2 bolt or 4 bolt, Truck
    3999290 Category: Engine Blocks
    Type: Big Block V8
    Date: 1970-1972
    Notes: 402, 2 bolt or 4 bolt, Truck
    3999290 Category: Engine Blocks
    Type: Big Block V8
    Date: 1972
    Notes: 402, 2 bolt or 4 bolt, Passenger
    3999293 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1990
    Notes: 366 tall deck, 4 bolt
    3999294 Category: Engine Blocks
    Type: Big Block V8
    Date: 1968-1984
    Notes: 427 tall deck, 4 bolt
    473478 Category: Engine Blocks
    Type: Big Block V8
    Date: 1977-1990
    Notes: 427 tall deck, 4 bolt
    495102 Category: Engine Blocks
    Type: Big Block V8
    Date:
    Notes: 4 bolt, aluminum, CanAm, 4.5 bores


    READ THROUGH THese LINKs, and sub links
    http://garage.grumpysperformance.com/index.php?threads/finding-a-machine-shop.321/

    http://garage.grumpysperformance.co...-state-muscle-or-project-car.4318/#post-18620

    http://garage.grumpysperformance.co...ll-of-receipts-is-not-proof.10281/#post-46628

    http://garage.grumpysperformance.co...etting-started-in-the-car-hobby.339/#post-415
     
    Last edited: Oct 17, 2017
  13. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    Number Details
    10045427 Category: Cylinder Heads
    Type: Big Block V8
    Date:
    Notes: rectangle port, Pontiac/Chevy Aluminum, 91cc chambers, Large Port, race
    10049875 Category: Cylinder Heads
    Type: Big Block V8
    Date:
    Notes: rectangle port, Pontiac/Chevy Aluminum, Small port, race
    10051128 Category: Cylinder Heads
    Type: Big Block V8
    Date:
    Notes: rectangle port, Bowtie, Aluminum, 72cc chambers, Symmetrical ports
    10051129 Category: Cylinder Heads
    Type: Big Block V8
    Date:
    Notes: rectangle port, Bowtie, Aluminum "raw" casting, Symmetrical ports
    10052902 Category: Cylinder Heads
    Type: Big Block V8
    Date:
    Notes: oval port, open chamber, MkIV, 427 tall deck
    10101140 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1991+
    Notes: oval port, closed chamber, Gen.V 366 tall deck, 427 tall deck
    10114156 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1991+
    Notes: oval port, open chamber, Gen.V & VI 454, 118cc chambers
    10141279 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1996+
    Notes: oval port, closed chamber, Vortec 7400, 100cc chambers
    10487052 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1977-1990
    Notes: oval port, open chamber, 366 tall deck
    12363391 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1996+
    Notes: oval port, open chamber, Bowtie, Aluminum, Signature Series, fits MKIV, Gen.V, Gen.VI, 110cc chambers
    12363401 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1996+
    Notes: rectangle port, open chamber, Bowtie, Aluminum, Signature Series, fits MKIV, Gen.V, Gen.VI, 118cc chambers
    12558162 Category: Cylinder Heads
    Type: Big Block V8
    Date: 2001+
    Notes: oval port, closed chamber, Gen.VII,"Vortec 8100", 8.1L, 496, truck
    12560241 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1998+
    Notes: oval port, closed chamber, Vortec 7400, 100cc chambers
    12562932 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1991-1995
    Notes: oval port, open chamber, Gen.V, truck crate motor, 118cc chambers
    12562933 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1991-1995
    Notes: oval port, open chamber, Gen.V, 118cc chambers
    12562934 Category: Cylinder Heads
    Type: Big Block V8
    Date: 2000+
    Notes: rectangle port, open chamber, Gen.VI 502 Marine
    14011077 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969+
    Notes: rectangle port, open chamber, Aluminum, fits MKIV, "C-port", 118cc chambers, also sold as a "solid" head
    14044861 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1984-1996
    Notes: rectangle port, Bowtie, Aluminum, MkIV, "raised runners", 1st design, 105cc chambers
    14044861 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1996+
    Notes: rectangle port, Bowtie, Aluminum, Signature Series, fits MKIV, Gen.V, Gen.VI, raised runners, 2nd design, 115cc chambers
    14044861 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1984-1996
    Notes: rectangle port, Bowtie, Aluminum, MkIV, "raw" casting of "861" MKIV
    14081045 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1978-1987
    Notes: oval port, open chamber, 454
    14081052 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1985-1987
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, 454 Truck, Marked "HiPerf"
    14092359 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1986-1990
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, Marked "HiPerf"
    14092360 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1986-1990
    Notes: oval port, open chamber, 454 Truck, peanut round ports
    14096188 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1970-1971
    Notes: rectangle port, open chamber, 454 service replacement, also used on later Mark IV LS-6, LS-7 and 454 HO crate motors, 116cc chambers

    Number Details
    14097088 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1991+
    Notes: rectangle port, open chamber, Gen.V 454/502 HO, 118cc chambers
    24502585 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1997
    Notes: rectangle port, Olds/Chevy, DRCE 2, Pro Stock aluminum, for blocks w/4.900" bore spacing
    25534404 Category: Cylinder Heads
    Type: Big Block V8
    Date: 2004
    Notes: rectangle port, Olds/Chevy, DRCE 3, Pro Stock, aluminum, for blocks with 4.900" bore spacing
    330864 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1984
    Notes: oval port, open chamber, 396, 402, 366 tall deck, 427 tall deck, 454 Truck
    330865 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1984
    Notes: oval port, open chamber, 396, 402, 366 tall deck, 427 tall deck, 454 Truck
    330866 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1978
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck
    330867 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1973
    Notes: oval port, open chamber, 427 tall deck
    336765 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1978
    Notes: oval port, open chamber, 427 tall deck
    336768 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1973-1976
    Notes: oval port, open chamber, 427 tall deck
    336781 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1973-1985
    Notes: oval port, open chamber, 454, 118cc chambers, 256/114cc ports
    343771 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1986
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, 454
    343772 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1986
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, 454
    343783 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1970-1976
    Notes: oval port, open chamber, 454 Truck
    346236 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1975-1987
    Notes: oval port, open chamber, 454, 120cc chambers, 225/116cc ports
    352625 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1970-1976
    Notes: oval port, open chamber, 454 Truck
    353049 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1973-1984
    Notes: oval port, open chamber, 454, 122cc chambers, 255/119cc ports
    366765 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1974-1978
    Notes: oval port, open chamber, 427 tall deck
    3856206 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1965-1966
    Notes: oval port, closed chamber, 396, 97cc chambers
    3856208 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1965
    Notes: rectangle port, closed chamber, 396 425hp, 109cc chambers, 396/375hp "Z-16" Chevelle
    3856213 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1966-1982
    Notes: oval port, closed chamber, 366 tall deck, 427 tall deck
    3856260 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968
    Notes: oval port, closed chamber, 396 Truck
    3872702 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1965-1966
    Notes: oval port, closed chamber, 396, 427, 98cc chambers
    3873858 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1965-1967
    Notes: rectangle port, closed chamber, 396, 427, 109cc chambers
    3876875 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1977-1985
    Notes: oval port, open chamber, 427 tall deck
    3904390 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967
    Notes: oval port, closed chamber, 396, 427, 98cc chambers
     
  14. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    http://www.novak-adapt.com/knowledge/engines/about/chevy/chevy-big-block-v8

    Number
    Details
    3904391 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967
    Notes: rectangle port, closed chamber, 396, 427, 107cc chambers
    3904392 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967
    Notes: rectangle port, closed chamber, 427, Aluminum, L88, L89, 107cc chambers
    3904393 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1976
    Notes: oval port, open chamber, 366 tall deck
    3908952 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967
    Notes: oval port, open chamber, 427, "M.Truck", Marine
    3909802 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967
    Notes: oval port, closed chamber, 396, 427, 101cc chambers
    3917215 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967-1968
    Notes: oval port, closed chamber, 396, 427, 101cc chambers
    3917219 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1985
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck
    3919840 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1967-1969
    Notes: rectangle port, closed chamber, 396, 427, 107cc chambers
    3919842 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1969
    Notes: rectangle port, closed chamber, 396, 427, Aluminum L88, L89, 107cc chambers
    3931063 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1969
    Notes: oval port, closed chamber, 396, 402, 427, 101cc chambers
    3933148 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969-1984
    Notes: oval port, open chamber, 1969 396/265hp, 366 tall deck, 427 tall deck, 112cc chambers
    3933149 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1976
    Notes: oval port, open chamber, 427 tall deck, 122cc chambers
    3935401 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1976
    Notes: oval port, open chamber, 427 tall deck
    3946074 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969-1971
    Notes: rectangle port, open chamber, 1969 427 L88, ZL1, Aluminum, 118cc chambers, 1971 454 LS6, "round exhaust port"
    3964290 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969-1970
    Notes: oval port, closed chamber, 396, 402, 427, 454, 101cc chambers
    3964291 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969-1972
    Notes: rectangle port, closed chamber, 396, 402, 427, 454, 109cc chambers, Large or small hex spark plugs used, crate motor usage after 1970.
    3965198 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1969
    Notes: oval port, closed chamber, 396 Truck
    3975950 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1970
    Notes: oval port, open chamber, 396, 402 Truck, 366 tall deck, 427 tall deck
    3986133 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1985
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, 454 Truck
    3986135 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1969-1973
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck
    3986136 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1984
    Notes: oval port, open chamber, 366 tall deck, 427 tall deck, 454 Truck
    3993820 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1971
    Notes: oval port, open chamber, 402, 113cc chambers, 255/114 ports
    3993820 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1971-1984
    Notes: oval port, open chamber, 454 Passenger and Trucks, 113cc chambers, 255/114 ports
    3994026 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1971
    Notes: rectangle port, open chamber, 454 LS6, 118cc chambers
    3999241 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1972
    Notes: oval port, open chamber, 402, 454, 113cc chambers

    Number Details
    473328 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1968-1969
    Notes: oval port, open chamber, 366 tall deck
    6272292 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1970-1978
    Notes: oval port, open chamber, 402, 454
    6272990 Category: Cylinder Heads
    Type: Big Block V8
    Date: 1970+
    Notes: rectangle port, open chamber, 454 service replacement, used on some MKIV crate engines, 118cc chambers
     
    Last edited: Oct 13, 2016
  15. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

  16. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    Dart block: https://www.summitracing.com/parts/drt-31273444

    World Products block: https://www.summitracing.com/parts/wrl-081101

    [quote/wolfplace]Here is a short list of most of the machine work when I do them here:
    All oil galley threads are checked & retapped as necessary
    Freeze plug holes and rear cam plug holes are chamfered
    Bottoms of the cylinder bores need to be chamfered
    Grind valley oil returns
    Fuel pump cavity oil return checked and addressed if needed
    Remove main caps, retorque 2 times, install oil pump & check main bore size, align bore / hone as necessary
    Lifter bores are checked & resized as necessary
    Blocks are decked, in most cases to zero
    Blocks are bored & plate honed to size.
    Jet washed, cam bearings installed.[/quote]

    it pays too shop carefully as the blocks occasionally go on sale
    I'd also point out its best to deal with a well known supplier,
    and I sure would never consider a sale from E-BAY, or craigs list unless it was local and you could closely inspect it personally,
    its not unheard of for some guy's too either screw up some machine work and try to sell off the damaged block to cut their losses, or to sell a used damaged block.
    yes you might get a damn good deal on some guys 1/2 finished engine project, where the original owner just ran out of cash,
    at a local machine shop, but thats not common.

    http://garage.grumpysperformance.com/index.php?threads/measuring-block-deck-height.3759/


    http://garage.grumpysperformance.co...-brief-big-block-chevy-history.951/#post-5878

    http://garage.grumpysperformance.co...l-deck-truck-build-questions.5602/#post-17105

    http://garage.grumpysperformance.com/index.php?threads/building-a-tall-deck-bbc.188/#post-28633

    http://garage.grumpysperformance.com/index.php?threads/chevy-big-block-vi.9857/#post-57595

    http://garage.grumpysperformance.com/index.php?threads/block-prep.125/#post-5352

    http://garage.grumpysperformance.com/index.php?threads/chevy-big-block-vi.9857/#post-37553

    http://garage.grumpysperformance.co...k-big-block-related-threads.10391/#post-42992


    http://garage.grumpysperformance.co...increase-a-454-displacement.10589/#post-45343

    http://garage.grumpysperformance.co...connecting-rod-compatability.9320/#post-33722

    http://garage.grumpysperformance.co...375-or-4-5-big-block-stroker.6430/#post-20326

    http://garage.grumpysperformance.com/index.php?threads/another-496bbc.5123/


    http://garage.grumpysperformance.co...big-block-stroker-big-enough.6132/#post-19023

    http://garage.grumpysperformance.com/index.php?threads/block-prep.125/page-2#post-58033

    http://garage.grumpysperformance.com/index.php?threads/aftermarket-heads-for-a-bbc.12316/#post-70601

    http://garage.grumpysperformance.co...der-head-choice-and-options.13247/#post-69070

    http://garage.grumpysperformance.co...t-intake-on-oval-port-heads.13146/#post-69975

    http://garage.grumpysperformance.co...pes-of-crankshaft-steel.204/page-2#post-46231

    http://rehermorrison.com/assets/DART-PREPPED-BIG-M-BLOCKS.jpg

    [​IMG]

    OF IF YOU HAVE DEEP POCKETS
    http://www.newcenturyperformance.com/Blocks.htm

    https://www.summitracing.com/search/product-line/dart-big-m-big-block-chevy-aluminum-bare-blocks

    http://dartheads.com/dart-product/big-m-aluminum/

    http://www.lukovichracing.com/racing-blocks.html

    http://www.donovanengines.com/donovan-engineering-aluminum-big-block/

    https://www.billmitchellproducts.com/aluminum-bbc/

    http://www.shafiroff.com/chevy-crate-engine/540-realstreet-lite.php
     
    Last edited: Nov 14, 2017
  17. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

  18. Grumpy

    Grumpy The Grumpy Grease Monkey Staff Member

    The 427ci Big-Block: Comparing L88, ZL1, ZZ427 Engines

    http://www.chevyhardcore.com/tech-s...ci-big-block-comparing-l88-zl1-zz427-engines/


    [​IMG]

    Since its inception, the 427 cubic-inch Chevrolet big-block has become a legend for engine enthusiasts around the world. Whether it’s a small-block stroker or big-block powerhouse, chills seem to find their way up the neck of those lucky enough to have one in their ride.

    The first of a three-part installment will be dedicated to the series of 427 cubic-inch engines that were so popular in the late-60s musclecar era. Part one will take a look back at the early L88 and ZL1 engines and compare them to the modern day ZZ427. In the coming months, part two will show how to build a modern day ZL1 using the aluminum block still available from Chevrolet Performance and aftermarket parts. Finally, part three will cover what goes into building a modern day ZZ427 using parts from Chevrolet Performance.

    [​IMG]
    The pre-production L88 big-block was introduced in 1967 and was first seen in passenger cars in 1969.

    The Legendary L88

    The L88 engine was introduced in 1967, and although it was only offered in production vehicles until 1969, its legacy has carried on for decades. Only the informed would have been impressed with a quick glance under the hood, however, each year brings about improvements, creating a legacy that has survived into modern times.

    [​IMG]
    The L88 was produced from 1967 to 1969, and featured aluminum heads.

    Although a forged-steel crankshaft with forged I-beam rods was used, the beam portion of the rod wasn’t quite up to the task of supporting nearly 500 horsepower for any length of time. A weak point was quickly identified, and it was cured the following year with a new, thicker connecting rod that included floating wrist pins and spiral-lock retainers. The 3/8-inch knurled shank rod bolts were also replaced with 7/16-inch smooth shanks.

    The pistons were also forged. With the availability of high-octane leaded fuel, the compression ratio was higher than most street engines today. Static compression was calculated at 12.5:1 requiring at least a 103 octane fuel. The increased compression allowed the relatively short stroke of the 427ci engine to produce plenty of torque.

    The L88 used the same solid lifter camshaft profile for all three years. Duration was advertised as 326 degrees on the intake, while the exhaust breathed a bit longer at 334 degrees. Lift at the valve was .540 and .560-inches for the intake and exhaust respectively. The aggressive cam profile also required a third inner damper spring to control the valves at speeds up to 7,000 rpm. Rocker arms were stamped steel and required a longer slot for the L88’s high lift. Pushrods were also a hefty 7/16-inch diameter.



    • [​IMG]
    • [​IMG]
    L88 Aluminum cylinder heads.

    Aluminum cylinder heads reduced the big-block’s overall weight by 70 pounds compared to the iron head versions. Closed combustion chambers were used with the first generation of L88 heads, and chamber size poured out at 106.8cc. Intake valves measured 2.19-inches and exhausts were 1.72-inches. Intake ports were a rectangular shape, and exhaust ports were squared-off to match up with the exhaust manifold.

    [​IMG]
    Rectangular ports as used on the ZL1 and L88 heads are compared to oval ports used on trucks.

    In 1969 significant improvements were made for the aluminum cylinder head. Intake ports were reshaped, and material around the spark plug was removed, allowing for 30 percent more airflow. The pop-up piston was also reshaped with airflow in mind. As a result of the 118cc open chamber and reduced piston volume, compression was lowered to 12.0:1. However, the improved design still resulted in more power. The exhaust ports were also rounded to match tube headers, further extending its power capabilities.

    A dual-plane aluminum intake manifold was used, and the carburetor pad accepted a standard four-barrel Holley. The divided-plenum under the carburetor was milled down to create an open chamber on the high-rise intake. In 1969, the divider was trimmed down even further to accompany the better flowing cylinder heads.

    • [​IMG]
    • [​IMG]
    Chrome valve covers and natural finish heads offered a more stylish look.

    Only the intake manifold was left unpainted for the 1967 versions; the aluminum heads were covered in orange. Chrome valve covers were installed in 1968, and Chevy left the bare aluminum finish of the heads unpainted, making the engine a bit more aesthetically pleasing.

    In order to compete in Production Class racing, the engine needed to be street legal from the factory. Although a PCV valve (Positive Crankshaft Ventilation) was widely used starting in 1963, the L88 utilized a road draft tube in 1967, which meant it could not be licensed in California. However, all vehicles, starting in 1968, were required to have a PCV system and a purified exhaust. As a result, even the high-performing L88s came with a belt-driven Air Injection Reaction (AIR) pump and PCV system. The government also mandated the installation of a heater and defroster on all street cars, requiring a heater hose connection on the intake manifold.



    The Corvette was Chevrolet’s flagship performance car, and it was logical that the Bow Tie’s most powerful engine be featured in the Corvette. However, Zora Duntov previously argued that the early 348ci and 409ci engines would be detrimental to the car’s handling because of its weight. Nevertheless, big engines with big power dominated the 1960s, forcing the second generation of Corvette to be built with this in mind. The production of the aluminum head L88 in 1967 reduced the weight of the large displacement big-block to 610 pounds overall, but there were still pounds to shave.



    Feeding The Animal
    [​IMG]

    In 1967, the L88 engine was equipped with an 850 cfm vacuum-secondary Holley carburetor.

    In 1969, Chevrolet switched to a mechanical-secondary carburetor.

    The ZZ427 uses a 770 cfm vacuum-secondary carburetor from Holley, and the electric choke is fully functional.

    Developing The Aluminum Block


    While the heavy big-blocks were holding their own in the drag race scene and stock car racing, weight kept these powerhouses out of the Can-Am sports car series. For those guys, Chevrolet R&D had been supplying all aluminum 327ci small-block racing engines to Chaparral cars in Midland, Texas, since 1963. When rumor hit that Ford was releasing an all-aluminum 427ci for the 1968 season Vince Piggins and his product promotions group countered with an aluminum block 427ci Chevrolet to be offered to the Can-Am competitors.

    Piggins was able to see beyond the Can-Am scene, and also lobbied to bring the aluminum block to production cars. Excited to trim some pounds off the L88 for the Corvette, Duntov supported the idea 100 percent. Fred Frincke, casting designer for the L88 aluminum head, was now on the production engineering team and designed the aluminum production block. In 1969, the ZL1 engine was born.

    A Fledgling Legend: The ZL1

    In addition to the second design L88 cylinder head, 1969 was a big year for the “Rat” engine, as Chevrolet offered its first all-aluminum big-block for production cars. The ZL1 was a Regular Production Option (RPO) for the Corvette, and a Central Office Production Order (COPO) for Carmaros that were strictly intended for racing.

    [​IMG]
    The aluminum 1969 ZL1

    The now-coveted block was made of 356-T6 aluminum and produced at the Tonawanda foundry in New York. A programmable five-axis, omni-mill, machining center, shaped the aluminum castings into the final state. Thicker decks, bulkheads, and cylinder walls were utilized with additional core supports, gussets, and reinforcement webs for strength. Cylinder liners were needed, and were made of cast iron. These liners were frozen and then placed inside of a heated block. When both returned to room temperature, they wer inseparable. All of the primary dimensions of the ZL1 block matched its iron sibling.

    The aluminum block did feature a main oil galley that was moved next to the camshaft and offered a provision for an external dry-sump system. The use of additional head bolts also carried over from the competition blocks to production units. Two threaded tabs protruded into the lifter valley from of each deck to provide extra clamping force.



    Other than the block and camshaft, the ZL1 was identical to the L88. Both used the second design cylinder head that flowed 30 percent better than the first. The ZL1 capitalized on the extra airflow by utilizing a more aggressive camshaft. Intake valve lift was increased .020 inches to .560 inches, while the exhaust reached .600 inches. Intake duration was reduced to 322 degrees advertised duration; the exhaust duration was unchanged from the L88 camshaft. An aluminum timing gear with nylon coated teeth was attached to the camshaft and driven by an inverted tooth chain.

    [​IMG]

    Conservative power ratings for the ZL1 were averaged at 525 horsepower. Installing a set of tube headers helped the peak number grow closer to 600 horsepower, but all that power came with a hefty price tag attached and added $4,718.35 to the bill, doubling the price of a Corvette coupe. Sticker shock surely contributed to the rarity of this nostalgic masterpiece. Government regulations required lower-octane fuel and consequently lower compression ratios. Chevrolet added a longer stroke to make up for the lost power, and in 1970 the 454ci engine replaced the L88 and ZL1 engines. The only year it was offered in a production car was 1969.

    [​IMG]
    The modern day ZZ427.

    Everyone’s ZZ427

    The L88 engine is one of the most popular big-block engines in Chevrolet’s history. While the aluminum-headed 427ci was only offered in production vehicles between 1967 and 1969, its demand carried on for decades. Chevrolet Performance resurrected the 427ci Rat from the grave, and packed in some modern goodies.

    “The ZL1 and L88 were only produced for a couple of years and were designed to burn race fuel,” says Bill Martens, Chevrolet Performance special programs manager. “The modern-day ZZ427 has a pump-gas friendly 10.1:1 compression ratio, which makes this 427ci streetable.”



    The bore and stroke dimensions have changed slightly. A 4.250-inch bore is just a tick smaller than the 60s version, while the stroke grew to 3.766 inches. Both the crankshaft and connecting rods are constructed of 4340 forged-steel, while the pistons are forged aluminum. The eight slugs have a smaller dome than the previous engines to reduce the compression ratio to 10.0:1, allowing the use of 92 octane pump gas. It still puts out a stout 480 horsepower.



    The modern-day ZZ427 has a pump-gas friendly 10.1:1 compression, which makes this 427ci streetable. – Bill Martens, Chevrolet Performance[​IMG]

    Camshaft designs have changed tremendously over the past 40 years, and the ZZ427 features the better performing, more reliable roller camshaft. The solid tappet lifters have been replaced with hydraulic rollers, eliminating lash adjustments for a maintenance free valvetrain. This allows for more power in lower RPM ranges, enhancing the drivability and power range for street applications. Duration is measured at .050-inch lift and comes out to 224 degrees for the intake and 234 degrees for the exhaust. Valve lift works out to .527 inches on the intake and .544 inches on the exhaust with the 1.7:1 aluminum roller rocker arms.


    While the ZZ427 uses an iron block and aluminum heads like its L88 predecessor, the new versions are quite different than the old school production. Cylinder head intake ports are a true oval shape, and valve size stayed the same as the second generation old school heads. But, ovate wire beehive springs are used in place of the triple-spring setup, allowing for better valve control with less pressure, heat, and wear on the springs. Also, the combustion chambers have shrunk to 110cc.

    [​IMG]
    Exhaust ports were rounded to match tubular headers for 1969.

    The Gen VI iron block has the main oil gallery next to the camshaft, just like the ZL1, and all five main caps benefit from the extra clamping force of four bolts. A one-piece rear main oil seal replaced the two-piece design of the 60s, and the front timing cover is a six-bolt design with an integral timing pointer designed to house a high-strength, single row timing chain. The ZZ lifter bores are longer with a machined boss on the top edge that accepts roller lifters with dog-bone style retainers. Finally, the deck surface of the ZZ has a modified, teardrop-shape coolant passage, making any head gasket designed for the Mark IV big-block incompatible.

    Whether it’s the popular aluminum-headed L88, an ultra-rare aluminum block ZL1, or a modern day ZZ427, it is certain that the 427ci has made an impression on the automotive enthusiast. Stay tuned for more as we cover what it takes to build one of these iconic big-blocks for yourself.
     

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