alex said:
Chevrolet 350 Small-Block Comparison - Your Old 350 Block Sucks - Hot Rod Magazine
We compare a stock small-block and four aftermarket blocks to determine what fits your needs better. Check it out in the October 2012 issue of Hot Rod Magazine
and lifter gallery
,piston bore walls,
block main cap web support areas
heads between the valves in valve seat area
look for stripped head and manifold and oil pan mounting bolt threads,
in threaded holes and cracks in block radiating from the holes
http://garage.grumpysperformance.co...block-cylinder-wall-thickness.976/#post-21036
https://www.chevrolet.com/performance/engine-components/small-block/production-based-blocks
http://garage.grumpysperformance.com/index.php?thr...
http://garage.grumpysperformance.com/index.php?thr...
http://garage.grumpysperformance.com/index.php?thr...
keep in mind that the VAST majority of guys that say they have a 500 hp plus SBC are bragging about,
either an engine that really makes considerably less true power ,OR, in many case's its an engine that dyno
tested at 500-hp-550 hp spinning at 6500 rpm , but its driven the vast majority of the time , when its driven,
probably on week ends or at car club meets ,
at most a few hundred miles a month, or in most cases a a few hundred miles a year.
and the majority of that time the engines driven at rpm and load levels FAR lower than required to access the full 500-hp-550 hp
one of the guys I helped build a serious 428 pontiac engine for , in his 1967 firebird
, has a dyno slip showing it made a bit over 600 hp, its certainly impressive,
but keep in mind he has a 250 wet nitrous plate on the car,
and in the 25 plus years hes owned the car with that engine hes done a few burn-outs,
attend a few car club meets, and by his admission puts under 500-1000 miles on the car a year at most.
I helped a local guy build a 377 SBC that dynoed at about 515 hp N/A, hes had the engine in a 1968 camaro for decades ,
he will pull out the dyno test results on a seconds notice,
I doubt hes driven the car more than 50-100 miles a year in the last 20 years,
its a well waxed and carefully cleaned, (damn impressive) garage queen.
the guys that BEAT on those O.E.M. engines every few weekends at the drag strip,
tend to find out, about the results of the component durability,
rather quickly and about CUMULATIVE STRESS.
while we all know guys that have built impressive SBC car engines, using O.E.M. blocks
how many of those guys seriously race the cars for years without issues?
http://garage.grumpysperformance.co...ing-cast-iron-can-make-a-preacher-cuss.12647/
http://garage.grumpysperformance.com/index.php?threads/block-prep.125/
http://garage.grumpysperformance.com/index.php?threads/grinding-block-for-stroker-assembly.2855/
http://garage.grumpysperformance.com/index.php?threads/engine-block-cylinder-wall-thickness.976/
you bring up a point that is almost constantly being debated
(but mostly among the average performance car hobbyists, not engine builders)
even chevy rates most production small blocks at under 400hp, Id also point out that a great many guys claiming to have a 450hp-500 hp engine are going to be shocked and disappointed if they get the car accurately dyno tested.
plus the fact that an engine that may actually reach 500 peak hp, is generally operated at far lower power levels over the vast majority of the time so marginal bearing support, oil flow and cooling ,main cap movement etc. are not huge factors in that engines durability most of the time.
That and Id bet 90% or more of the time when an engine fails some other factor is blamed, if the main cap cracks or a main bearing fails , or a cylinder wall cracks and coolant hydraulically locks a piston at 6000rpm ,it will rapidly cause a great deal of related failures and if a guy disassembles a failed engine and finds a trashed piston, bent valves a cracked cylinder head etc. the cause or original failure point that caused the cascade of related failures is rarely investigated accurately, and a main bearing failing can easily be blamed on something that happened later, like a rod coming loose from a piston, bent valves a cracked cylinder head, a broken crank,etc.
the damage can be extensive, and similar, but the order of the cascade failure can be difficult to diagnose
while valve train and lube failures are common, a failed main bearing or flexing main cap causing the loss of oil pressure can be and is frequently over looked or consider a result not a cause.
Your Old 350 Block Sucks
Written by Mike Finnegan on August 19, 2012
VIEW ALL 29 PHOTOS
There’s a limit to what you can do with old-school GM passenger-car parts, and the breaking point is relatively low when it comes to the Gen I small-block Chevy cylinder block. Sure, you can bore the block to within an inch of its life and fill the water passages with concrete before stuffing a 4.00-inch stroker crank into it and make decent power for a while. The fun won’t last long, though, when the block cracks, leaks water, or flexes enough to pinch the main bearings or lose the head-gasket seal. To find the beef of the stock 350 and the aftermarket alternatives, we had Pfaff Engines sonic-test six different blocks with 350-style main journals (some are available with 400 main journals) and standard deck heights to see how far they could be bored and how thick the decks were. We also put them on the scale and called every manufacturer to find out how much work it is to drop a big arm into each one. The results were surprising, but we are savvy small-block Chevy shoppers now.
Dart Machinery SHP
Model PN 31161211
Block Composition SAE grade G3000 cast gray iron
Bore 4.120-inch (unfinished); 4.165-inch max
Maximum Stroke Clearance 3.750 out of the box using steel rods; 4.000 with some pan-rail clearancing and a small base-circle camshaft (0.900 diameter)
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.430 inch
Maximum Recommended Horsepower 600
Weight 170 pounds
Price $1,578.57 from DartHeads.com
Chevrolet Performance
Model PN 101051237 late-model, one-piece rear main seal (adapter available for two-piece seal)
Block Composition Cast iron
Bore 4.040 inches (stock bore is 4.000 inch)
Maximum Stroke Clearance 3.750 inches with steel rods
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.456 inch
Maximum Recommended Horsepower 360
Weight 157 pounds
Price $789.95 at SDPC.com
World Products Motown II
Model PN 084010 nodular iron main caps; PN 084110 billet steel main caps
Block Composition Cast iron
Bore 3.990-inch (unfinished); 4.200-inch max
Maximum Stroke Clearance 4.000 inches (pan rails are factory-notched for H-beam steel rods)
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.338 inch
Maximum Recommended Horsepower World Products told us four-digit power, but not to quote them on it
Weight 225 pounds (deduct 9-10 pounds when boring to 4.125 inches)
Price $2,151.95 at SummitRacing.com (nodular iron main caps, splayed billet steel caps are optional)
Dart Machinery Iron Eagle
Model PN 31121212 (0.391-inch raised cam and 0.800-inch spread pan rail versus stock 350 Chevy
Block Composition Class 32B cast iron
Bore 4.120-inch (unfinished); 4.185-inch max
Maximum Stroke Clearance 3.875 inches out of the box using steel rods; 4.250 inches with pan rail and bottom of the cylinder clearancing
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.488 inch
Maximum Recommended Horsepower Dart wouldn’t give us a number, but assume 1,000-plus
Weight 195 pounds
Price $3,026.46 at DartHeads.com (includes optional 2.125-inch BBC-size cam journal
OE ’69 Chevrolet
Model Casting number 3932388 standard two-bolt main
Block Composition Cast iron
Bore 4.000-inch (stock); 4.060-inch max
Maximum Stroke Clearance 3.800 inches with steel rods
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.452 inch
Maximum Recommended Horsepower 360
Weight 171 pounds (includes cam bearings)
Price $200.00 (used standard-bore block)
Dart Machinery Little M Sportsman
Model PN 31131211 350 main journals; PN 31132211 400 main journals
Block Composition Class 32B cast iron
Bore 4.120-inch (unfinished); 4.165-inch max
Maximum Stroke Clearance 3.800 inches out of the box using steel rods; 4.000 inches with some pan-rail clearancing and a small base-circle camshaft (0.900-inch diameter
Deck Height 9.020 inch
Deck Thickness at Thinnest Point 0.488 inch
Maximum Recommended Horsepower Dart wouldn’t tell us, but we assume 1,000-plus
Weight 201 pounds
Price $2,314.45 at DartHeads.com (includes coated cam bearings, dowels, and freeze plugs)
The Science Behind the Sonic Checker
Sonic checkers, like NDT Systems’ CB110, determine the thickness of cylinder walls and decks by transmitting ultrasonic frequencies into metal, recording how long the signal takes to reflect back to the checker, and then converting that data into a measurement. It’s similar to the way a naval submarine’s sonar system operates to verify the range to a target, except that the frequency is much higher, 2-10 MHz, or two to ten million cycles per second in this instance.
The transmitter’s probe sends a short pulse into the metal using a coupling material such as water or oil, and then the checker records the total transit time through the test metal. This is called the sound velocity, which is what is converted into thickness readings used to determine if the cylinder walls or deck of our engine block are thick enough for the foundation of a reliable racing engine.
According to NDT Systems’ Greg Smith, designer of the CB110, the sound velocity is different for various types of metal. The pulse travels relatively slowly through cast iron, while it reflects more quickly through steel, and even faster in aluminum. Checking alloys complicates the readings to a degree because the metallurgy of a block fluctuates from one area to another enough to change the speed of the pulse by as much as 18 percent, ultimately affecting the thickness measurement by up to 0.055 inch. Using a test piece of material similar to the block you’re testing gives a reference for a “good” reading versus an incorrect one.
Did you know?
15 years ago, General Motors shipped the original tooling for the small-block Chevy from its Flint, Michigan, plant to the Toluca, Mexico, facility, where crate engine block production continues.
When to Buy a New Block?
At what point do you sell your stock block and invest in an aftermarket one? Engine design will dictate an upgrade if you plan to increase the stroke of the crankshaft beyond 3.800 inches or bore it more than 0.060 inch. Look closely at the sonic check results and you’ll see how thin the cylinder walls of a stock block are when you bore them to 4.125 inch. Cooling the engine also becomes an issue with an overly large bore. GM rates the original small-block cylinder case at no more than 360 hp, but we’ve seen them stay together at 600 hp or more by stabilizing the bores with a block fill (www.HardBlok.com is a well known supplier) up to the water jackets. Beyond that, we recommend stepping up to an aftermarket block. If you’re starting from scratch, consider the cost of sonic-checking, pressure-testing, and machining an old block before you ignore the option of spending more bucks on a new one. Here’s a rundown of what it costs to have Pfaff Engines chuck a block up in its five-axis machining center and boring machine:
- Bore and finish hone cylinders: $194.00
- Machine deck surface: $169.00
- Align hone main bearing journals: $206.00
- Sonic check bores and deck surface: $40.00
- Pressure test cooling system: $115.00
Baffled by the terms in this article? Here’s the lowdown on the more confusing ones.
Blind Tapped: This refers to boltholes that are drilled and tapped into the block without protruding into an open space, like the water jacket. Non-blind tapped holes require thread sealent on the bolts or studs and are prone to leaking water.
Siamese Bores: Early GM blocks have water passages between each cylinder bore. Late-model and aftermarket blocks have what are called Siamese or conjoined bores, which means there is no coolant passage between them. The metal-to-metal contact of each cylinder wall makes them more stable and prone to staying round under intense cylinder pressure that forced induction provides.
Splayed Bolts: GM passenger car blocks have main caps with bolts threaded straight down into the main webs. GM Bowtie racing blocks and most aftermarket blocks have splayed outer bolts in Nos. 2, 3 and 4 main caps. These bolts thread into the side of the block at an angle, usually around 10 degrees or greater. The side of the block has more material thickness than the bottom of the web, making it a stronger foundation for the bolts to grip.
Priority-Main Oiling: A factory 350 block’s oiling system sends oil from the pump to the filter, then to the lifters and then to the cam bearings. The main and rod bearings are the last to receive oil, which isn’t a good thing at high rpm or when you first start the engine. Priority main oiling reverses the path the oil takes, giving the main bearings the liquid of life first.
TWO BOLT MAIN CAP BLOCK
4 bolt SBC block
the block pictured above is NOT A CHEVY, but it gives you some idea of what the block internal coolant passages and cylinder walls look like
failure to verify clearances, verify valve train geometry , provide lubrication, and maintain cooling , stay out of DETONATION,or use of inferior components or exceeding your engines valve train control limitations, or red line on rotating assembly design strength, or failure of the main caps to maintain bearing clearances and oil pressure can get darn expensive
the rear cam tunnel freeze plug?
theres two, sizes
23/32-inch expansion plug or the 47/64ths (cam plug)
or
the dorman catalog showed both plugs for 62-68 327 & 67 up 350's also.
the small one is dorman # 555-049.
23/32 o.d.,
the large one is 555-080.
47/64 o.d.
just be sure an measure the one you knock out or the hole it fits and use an accurate caliper
if you check you'll find that stud girdle use does little or nothing for the individual main cap strength but it does marginally increase main cap stability and block flex.
now the potential difference is probably not worth the expense, in that your generally spending cash that would be better used in the purchase of the stronger aftermarket block casting from a known source like DART.
look through the links and read the sub links
the billet splayed main caps on the aftermarket block is the stronger route, but Id bet 90% of the guys building their first engine think they will save money using the O.E.M. block they already own.....well, until... they add up all the machine work costs and price of parts like aftermarket splayed caps, ARP main studs ,the labor costs from the machine shop, etc. but by that time the machine shop owner is smiling all the way to the bank, and youve just figured out the true cost of that cheaper O.E.M BLOCK
aftermarket blocks like dart have significantly thicker bore walls, main cap webs, decks, can be ordered with splayed and billet main caps
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!
read these links
http://garage.grumpysperformance.com/index.php?threads/casting-numbers-vin.93/#post-29983
HERES A STOCK PRODUCTION BLOCK, about $760-$900
http://www.jegs.com/i/GM+Performance/80 ... 7AodORoA_w
https://chevroletperformanceparts.com/catalog/chevrolet-performance-engines
http://www.summitracing.com/parts/sum-150100-30/overview/
http://www.lsmeng.com/Blocks.html
WORLD
http://www.theengineshop.com/products/e ... locks.html
dart
http://www.dartheads.com/products/shp-c ... block.html
http://www.hotrod.com/articles/hrdp-1210-chevrolet-350-small-block-comparison/
http://www.summitracing.com/parts/drt-31161211
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
RELATED INFO
http://www.studebaker-info.org/tech/Bea ... -3-402.pdf
http://www.agkits.com/bearing-failure-analysis.aspx
https://www.chevydiy.com/ultimate-guide-building-chevy-big-blocks-cylinder-blocks-instruction/
http://kingbearings.com/files/Engine_Be ... d_Them.pdf
http://garage.grumpysperformance.co...ing-to-partially-fill-coolant-passages.14545/
https://chevroletperformanceparts.com/catalog/chevrolet-performance-engines
Last edited by a moderator:
