block prep.


Staff member
alcohol is HYGROSCOPIC, its good for cleaning off some types of grease, but its not much help for more than cleaning,

The definition of hygroscopic is the property of readily absorbing moisture from the air, OR ANY PLACE IT COMES IN CONTACT WITH MOISTURE

it will greatly speed the evaporation rate of surface moisture it mixes with, and APPEARS to DRY THE SURFACE, but it won,t provide any protection, in fact it tends to speed corrosion forming
when I ran methanol alcohol in fuel injection units we had to run gas mixed with oil thru the units before we stored them even over a weekend or we saw rapid corrosion on brass and aluminum and steel components that got methanol soaked

a clean cotton rag soaked in ACETONE mixed with marvel mystery oil , followed by a spray of the new WD40 mix works as a corrosion barrier

marvel.jpg ... inhibitor/

if you have any doubts, do a simple test, clean two separate, identical disposable parts like two 30 penny common nails, clean one with the ACETONE mixed with marvel mystery oil , followed by a spray of the new WD40 mix and, clean one with the alcohol,and gas mix fuel you run or just alcohol alone and then, label each nail and place it on a paper plate, set them out on a shelf in the shop for 10 days and see the results


if you look at the 2 pictures I found posted (above)of a very common issue with engines stored for weeks or months during , or after a build, youll see the areas that were constantly soaked in oil failed to rust, yet those areas exposed to moisture in the air , no mater the low percentage still slowly form surface rust,this tends too be more cosmetic than structural in most cases but its easily prevented, the oil forms a moisture barrier that prevents rust but most oil eventually evaporates or runs off, spray any non painted surface with this product, and it will last at least a 1/2 year without rust in a semi dry environment like on an engine stand in a climate controlled trash bag, as it forms a very slow to degrade surface oily/wax like air barrier that will wash off with hot oil when the engine runs.

Ive only used it on a few engines so far over about a years time, but as far as Ive seen it just mixes with the oil in the engine with zero problem, Ive built and stored at least 8 engines now while useing it during storage and had zero issues and ZERO RUST FORM

ruust2.jpg ... inhibitor/


Staff member


solid fixture here in the forum
oh im sure its corrosive i just meant flushing alcohol thru the coolant passages and oil passages after you wash the block... as an alternative to blowing compressed air (which should be noted to use a water air separator so theres no water blowing out the tip of your air gun) to ensure theres no water trapped in there.. then follow it with some marvel mystery oil for preservation.


Staff member
I don,t see how anyone who's regularly building or re-building engines can not have access to a few tools to clean and dry out engine blocks, and a good pressure cleaner is one tool you really should have if your doing that type of block clean-up work. my son recently had his power pressure washer fail, and I lent him mine, which was basically functional but hardly running at ideal levels, it soon quit as it was at least 12 years old and Id run it occasionally with fuel laced with ethanol (A BIG MISTAKE) so when it quit and there were no parts available for repairs we both scraped up the cash to go 50%/50% on a new one from lowes with the firm understanding that neither of us will use ethanol laced fuel in it.
we managed to find a discount coupon and we got the pressure washer below for just under the listed price WITH the tax included









696471065909.jpg ... Heavy-duty
yes the block cleaning will still require a compressor, high pressure air nozzle .bore brushes and degreaser, paint and rust preventative plus plugs



as I'm sure your aware, after careful dis-assembly,an older engine that looks rather well used and un-loved and homely ,can look much different after a careful cleaning those parts will come out of a cleaning,wither you do it or have a local machine shop do it in far better condition and once cleaned and painted look like a totally different engine. personally Ive found the price of a 3200psi pressure cleaner, and particle blast cabinet, pays for itself very rapidly in what you save in cleaning costs you would have other wise spent at the machine shop.
(don,t forget to clean out the internal oil passages and replace the cam bearings and use brass freeze plugs)[/color]


don,t forget to PAINT all NON-machined surfaces with the correct heat and solvent resistant paint, install the cam bearings and gallery and freeze plugs correctly and to coat machined surfaces with rust barrier grease

the rear cam tunnel freeze plug?

theres two, sizes ON the SBC O.E.M. REAR CAM PLUG
1.23/32-inch expansion plug or the 1.47/64ths (cam plug)

the dorman catalog showed both plugs for 62-68 327 & 67 up 350's also.

plugs are roughly 1 5/8" on a O.E.M block sbc

the small one is dorman # 555-049.
1.and 23/32 o.d.,
the large one is 555-080.
1. and 47/64 o.d.
just be sure an measure the one you knock out or the hole it fits and use an accurate caliper

I got a cheap heat gun from harbor freight, and a long reach air nozzle to help blow out oil passages, too help rapidly dry pressure cleaned blocks before I spray them down with WD 40 specialist,to prevent surface dust rust forming its got a low heat high heat settings and makes safe, fast work of the heat shrink tubing...or fast drying a block and it helps WD 40 penetrate and remove moisture they are on sale now for 15 bucks but I paid 20 for mine...not great quality but so far it works as well as required ... 96289.html




yes its going to add some expense, (about $80 if you catch these on sale) but if you add the optional larger casters to an engine stand it allows you to maneuver the legs of the stand so they roll over the crane
probably a better design but not foldable
I like what you did, that looks nice,btw,
Ive got two types of engine stands designs in my shop,(4 engine stands)but I added 4 of these wheels to each stand ... _200442439





weldersta.png ... _200305213
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The Grumpy Grease Monkey mechanical engineer.
Staff member
when your cleaning older and filthy engine components you deal with,
crap like, rust old under-coating asphalt type sealants, grease, paint, sludge, dirt, grease,
and combinations of these, contaminants, that may have been baked in place for decades.
you can buy particle blaster cabinets (most guys call sand or bead blast cabinets)
but they require a great deal of air volume and pressure to function at a fully functional level for more than a few minutes of constant use,
require DRY AIR not just compressed air, and anything rather larger or heavier than a cylinder head is totally out of the question simply because,
of size and ease of handling considerations in most cases.

smaller parts can be washed in many cases






larger parts like rear differentials, engine blocks and transmission housings and suspension components ,drive shafts,frames,etc.
generally get repeatedly soaked in various solvents then the stiff brush and high pressure water jet cleaning, owning a decent pressure washer you can use on your own drive way or back yard sure beats having to deal with some tree hugger who gets nuts if you attempt to clean your old rusty cylinder heads in the car wash bay with the pressure wand quickly followed by a water removal process that starts with
lots of high pressure air jets blasting the moisture out of anyplace it might collect in,followed by the
heat gun and prodigious volumes of WD 40 if the object is to hopefully delay the formation of surface rust, long enough for the non-machined surfaces to be painted, and machined surfaced to be further rust barrier coated or sealed.

if your really bucks-up you have the room for and have built a solid sturdy work bench (YEAH I STILL DROOL LOOKING AT THIS) and have a place to get things up off the floor while you prep and clean and rust proof them other than just the engine stand or two.














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The Grumpy Grease Monkey mechanical engineer.
Staff member
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).
Here’s a Look at the Various Chevy Big-Block Casting Changes Through the Years



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 ( 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.

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.

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.

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.

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.


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.

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.

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.


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.


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.

The rear of the block features new plug holes, similar to what GM did with the small-block casting.


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.


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.
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The Grumpy Grease Monkey mechanical engineer.
Staff member
How to Prep an Engine Block for Paint
by Jason Unrau on

June 14, 2016


TWEETengine, you’ll probably want to paint the engine block. It serves a few purposes including being clean and attractive in appearance, protecting from corrosion and rust, and offering a custom look, even matched with the car’s paint color or your color of choice.

Painting the engine block is best done when the engine is completely disassembled. If you paint the engine block while the cylinder heads, hoses, intake, and belt-driven parts are still attached, your finished product will be covered in overspray and you won’t be able to clean the block properly, so the paint will start to peel soon after due to poor adhesion.

Part 1 of 4: Disassemble the engine completely
Step 1: Remove all the bolt-on parts from the engine. Take off the power steering pump, water pump, air intake manifold, and all the pulleys.

Remove the timing cover, cylinder heads, and any remaining bolt on parts.


before you remove the rotating assembly components number stamp the location and position so everything can be reassembled correctly

Step 2: Remove the crankshaft and pistons
. Unbolt and remove all the pistons and connecting rods from the crankshaft and remove them from the engine block.

Remove the crankshaft main bearing caps and remove the crankshaft from the block. Eliminate the possibility of getting paint on integral internal parts which can flake off and cause damage later on.


Step 3: Completely drain the fluids and remove dirt. Turn the engine on all sides and let fluids drip out until they stop.

Use compressed air to force fluids out of spots they may not drain from. Wipe any loose oil from the outside with a shop rag. Scrape off any excess crust or dirt with a scraper or wire bristle brush.

Part 2 of 4: Degrease the engine
Your engine block needs to be completely free of all dirt, oils and grease. If it has any oil left on it at all, the paint won’t properly adhere to the metal properly.

Materials Needed


Step 1: Spray the engine with the aerosol cleaner degreaser. Completely coat the engine in degreaser spray, letting it soak according to the instructions on the can.

Step 2: Rinse the engine with clean water completely. Spray it with a garden hose or a pressure washer to remove the degreaser.

Step 3: Remove water from engine block. Immediately after rinsing, blow the water off the engine block with your air compressor.

Water left on the metal surface can cause corrosion or rust to form, especially if your block is cast iron.

Step 4: Check for grease. Check that all the grease and oil are gone from your engine’s exterior surface.

Step 5: Re-apply degreaser as needed. If there are spots that remain, re-apply degreaser to those areas.

You can agitate the grease with a small brush to remove it from the engine block. Rinse the engine with water again to remove any remaining degreaser and dry the engine with compressed air once more.

Part 3 of 4: Mask the internal engine parts
For the rest of the prep and painting, you don’t want to get material inside the engine’s cylinders, on mounting surfaces, or in oil or coolant channels, so cover any surface you don’t want paint material entering.

Materials Needed

  • Masking tape
  • Newspaper or plain wrapping paper
Step 1: Cover large areas with newspaper. The cylinder head mounting surfaces should definitely not be painted, so cover them with newspaper.

Use a double layer for added strength, and protection if one layer tears. Apply tape around the border of the paper, lining up perfectly with the edge of the cylinder head mounting surface.

If you do happen to have the tape go over the edge of the surface, don’t fold it down against the engine block, cut off the excess with a cutting blade. Cover the bottom end of the engine in the same way on the surface where the oil pan mounts.


Step 2: Cover any small bolt holes and studs. Use a small piece of tape or insert an old bolt into the hole to prevent paint from getting into the threads.

Wrap any manifold studs with masking tape that are not being removed and cover any fluid channels with tape or plug with a rolled-up piece of newspaper or cloth.

Step 3: Double check the engine. Check over the whole engine to make sure you can’t see any openings to the inside of the engine.

If there are any spots, cover the void with tape or newspaper.

Part 4 of 4: Clean old, loose paint from the engine surface
For paint to adhere to your engine block for the long haul, it needs to be cleaned of any paint that is currently loose or may come loose in the near future. Use a media blaster to remove loosened paint.

Materials Needed

Step 1: Fill the hopper on your media blaster with media. Use a soda media to clean paint from your engine.

  • Note: Soda media, essentially granular baking soda, is an excellent media for safely removing paint and corrosion from your engine block. It is abrasive yet soft enough not to damage critical internal engine parts should it get on them.
Step 2: Attach media blaster and turn on compressor. Attach your media blaster to your air compressor and turn on the compressor, letting the compressor charge with air.

  • Warning: Make sure to put on your eye protection and dust mask.

Step 3: Get started using the blaster on your engine. Point the nozzle of the media blaster at the engine block and pull the trigger.

The soda media will blast away loose paint and rust from the engine block, exposing the metal underneath.

Step 4: Use the blaster over as much of the engine as possible. Move the tip of the media blaster back and forth over the engine block, removing as much loose material as you can.

Stop occasionally if you need to let the air compressor recharge with air or refill the media hopper.

Step 5: Finish blasting. Stop when there is nothing left to remove or no more paint is coming off.

Step 6: Use vinegar on the engine surface. Fill a spray bottle with one cup of white vinegar and one cup of water.

Spray the whole surface of the engine block with the vinegar solution. There will be foaming action that occurs as the vinegar neutralizes the soda media.

  • Warning: Be careful not to saturate the newspaper and masking tape.
Step 7: Blow the engine block surface dry with your air compressor. Once the engine block is dry, you are ready to paint the engine block.

  • Warning: Don’t wait for more than a couple days to paint the engine block or you may have to media blast corrosion and rust from the surface again before you paint it. Just the moisture in the air will cause the cast iron to rust.


The Grumpy Grease Monkey mechanical engineer.
Staff member
  1. BRIAN suggested I add this block deck rigidity mod

  2. deckpl3.jpg

Having a trust worthy and experienced and skilled machinist your dealing with is critical in any engine build,
you do realize the installation of those block deck with the added plugs,
must now be followed by the block deck surface, being milled,
its milled to provide a flat level surface for the head gasket,
and the plugs will cause the bore walls to be very slightly out of round until the bores are honed.
this is one of several reasons , the considerably thicker castings used on the aftermarket blocks like DART sells,
with the much thicker decks and blind head bolt holes that don,t allow the head bolts to enter the coolant jacket,
are preferred on serious performance SBC builds,

    • deck plugs marginally help reduce the bore wall and deck flex, potential,
      thus ring seal and head gasket seal,
      they have no real positive or negative effect on cooling,
    • simply because the coolant holes in those deck plugs,
    • are similar in size to the head gaskets , in most cases
  1. deckpl2.PNG

  2. ... tId=753475
  3. THE true eventual cost of all the machine work, on an O.E.M. block is usually far higher than most people initially imagine.
  4. one more reason purchase of a DART block makes a great deal of sense,
    why put more money into trying to get an O.E.M. block up to nearly the strength of a DART BLOCK,
    a level it can NEVER obtain, when the much stronger DART blocks made with thicker bore walls, main cap webs etc.
    costs less. and will be out of the box over 50% stronger in many areas and over 150% stronger in some critical areas
    for less total cost?
    yes we all want to save money, and you already own a O.E.M. block, but that block was never designed to handle the stress of racing and once you exceed about 450 hp,
    on a regular basis stress is cumulative, you are exceeding the blocks original intended stress limitations.
    we all know a few guys that have built impressive high horsepower engines on O.E.M. blocks, some live, many don,t
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The Grumpy Grease Monkey mechanical engineer.
Staff member
just remember that a thread chaser tap is not a thread CUTTING TAP ... 8/10002/-1

if you use taps youll need several sizes of tap holder t-handles


Lisle 70500 Tap Socket Set (this square drive socket set, socket set allows you to use swivels and ratchets on thread taps)
if youve ever chased threads in a block thats still in a car you have very likely found the typical taps T-handle can have clearance issues
well once the old head, and head gasket was removed there was a bunch of old gasket sealer left on the block and head surface,
and BOB reached for a rotary brush on a 1/2" chuck drill which..

I'm certain has been done by thousands of guys, in the past, but its a darn good way to screw up the gasket sealing surface.
(yes I know its been done thousands of times but its also resulted in dozens of guys with unexplained head gasket failures)
the problem is that its absolutely impossible to remove the old stuck on gasket material with a drill and rotary wire brush without doing at least some minor damage to the sealing surface and its all too easy to do damage that can cause head gaskets to leak

brass being softer is a marginal improvement over steel wire rotary brushes


an extended air power die grinder used with a nyalox synthetic brush is useful for removing old gasket material ... 99698.html

steel wire rotary brushes can rapidly damage a block or set of cast iron cylinder heads , and will very rapidly do so on aluminum, thus should NEVER be used , to remove gasket residue
the correct route is to spray the surface down with a gasket solvent spray, let it sit 15 minutes, re-spray , it may take two or even three coats of solvent but the residue will tend to wipe off with minimal force once soft and partly dissolved and then use a 6 inch wide (minimum ) , under gaskets but over the bores without tipping a sharp edge, of the thin flexible blade edge into a bore,while using minimal pressure , THIS IS EXTREMELY CRITICAL ON ALUMINUM HEAD GASKET SURFACES,


held almost parallel to the surface, the flex blade used with minimal pressure is used to loosen the old gasket residue, by slicing the loose gooey, mostly solvent soaked and mostly dissolved residue off the machined surface then wipe off the surface with a rag soaked in acetone. to remove any remaining residue, that way the mating surface is less likely to get gouged

Item number :


Dynatex 49673 Gasket Remover

be careful don,t get it on your skin, use plastic gloves®-03017?gclid=EAIaIQobChMIuLy_n8uv2QIVnLjACh2hgQ_vEAQYAyABEgLNDvD_BwE

using a decent shop vacuum while you remove gaskets tends to greatly reduce the chance or odd debris getting into places you don,t want or need that crap to get into
THIS IS THE ONE I PURCHASED AND I RECOMMEND IT, remember to change filter elements frequently and a couple quarts of water and a couple drops of dawn dish washing liquid in the water traps a great deal of dust in the lower body before it gets to the filter ... 5yc1vZbv79

if you want to be sure you get all the metallic trash removed,removing gaskets and using a thread tap to clean bolt holes followed by a solvent spray wash and a long tip high pressure air nozzle blowing the passages dry and clear, of solvent and clear of debris, along with the ling spray nozzle ,high pressure air, solvent and the vacuum is a hard combo to beat

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The Grumpy Grease Monkey mechanical engineer.
Staff member
After lots of issues with an old Mark IV I decided to sell it and bought a new Dart Big M BBC.

Had it completely machined and when picked up asked if everything went fine. Guy told me "we ran a tap on 3 main holes as the bolts were hard to turn giving incorrect torque readings.." I cringed... No chaser, a regular tap.

Finally took the block home after arguing and getting nowhere.. Whats done it's done I guess. Left it there for a while.

Last week bolted all mains up with the stock Dart bolts. Torqued up to 100 using darts lubricant. All OK, nothing felt funny and held up just fine.

Had a set of new ARP studs and installed those. Again torqued up in 3 steps to 110 as per ARPs instructions. All OK. Also clearances did not change at all with the studs, so will use these for piece of mind.

Returned to the shop, much to my regret, and got the taps dia measured. They are 0.012" larger than the studs dia.

Also measured the "side to side play" of the studs (without the main saddles on of course). Screwed them up all the way and then backed 1 turn. Measured as close to the main surface as possible. All of them move 0.0015" to 0.0025". The ones these ppl redid (the outer on the 3rd cap and the inners on 4th and 5th cap), have 0.003 to 0.004" side play (they of course felt "looser" just by feeling while screwing them on...

Now my question is: Should I leave as it is or fix it? I know the studs are clamping as they should, but once you spin a 75 lb crank to 6.000 or 7.000 rpm there will be a lot of punding down there, isn't it? So clamping force is one thing but I suppose the mains have to endure the extra forces a running engine will have... For (crossed fngers) a long time... This is not a race engine that will get torn down every weekend to check on things.

I have access to a nice large mill. Was thinking of drilling these threads out and inserting 1.25" helicoils tightly in place.. Am I overthinking this? So afraid to break up something I will never be able to afford again that I'm getting paranoid.

Sorry for the long post.. any opinions appreciated. If there's another way to check these holes please let me know.


well my first thought was why not call and talk to


as it is their block and their studs.
but I've used several DART big M blocks and dozens of sets of ARP main cap studs , and honestly, I don,t think your running any risk. big m block



The Grumpy Grease Monkey mechanical engineer.
Staff member


The Grumpy Grease Monkey mechanical engineer.
Staff member
100% alcohol absorbs water, but most rubbing alcohol is 50%-30% water already you would require pure alcohol wash after a good pressure cleaning with a grease solvent, and ideally hot high pressure water.
followed by a heat gun and WD40 on machined surfaces and paint on cast surfaces