Engine Block Cylinder Wall Thickness



Engine Block Cylinder Wall Thickness

Postby grumpyvette » December 29th, 2008, 10:37 am

HOW FAR CAN YOU BORE A BLOCK?

before you begin to have a engine block bored more than about .030 over size its a good idea to have the blocks bore walls sonic tested, bore walls are rarely if ever uniform in thickness from top to bottom or side to side, or concentric with the bore center line.
its common for one wall in a cylinder to be significantly thinner than the other walls
this might sound like a unneeded extra expense but if your going to put several hundred dollars in machine work into a block you want to be fairly sure it won,t fail under stress wasting all that time and money, plus any resulting damage that might result.

boring a BIG BLOCK CHEVY block to more than about .060 over its original intended bore diameter,or sleeving the bore ,some times its the only way to save a block, but in many cases the O.E.M. blocks are so thinly cast that you'll have bore distortion and less than ideal bore, to piston ring sealing due to the cylinder wall thickness and /or less than ideal ring sealing, once the blocks really hot. making swapping to an aftermarket DART , world products or BOWTIE block with the thicker castings and better alloy metal,a better long term option, you cant tell how thick your cylinder walls are without sonic testing them as casting flaws, core shift and years of rust can make any block walls far thinner than you might assume them to be
let me point out a few facts, boring a cylinder takes 1/2 the bore increase off each side of the cylinder wall, and almost any big block will allow a careful machine shop to physically cut the finished bore size to be .100-.125 oversize , or a SBC .060 over bore,THAT IN NO WAY MEANS the remaining wall thickness thats left will be RIGID enough and STIFF enough to maintain a solid ring seal,or not flex and crack after repeatedly being stressed, at higher rpms and if the bore wall flexes to any significant degree it rapidly results in loss of effective compression rapid ring wear and potentially a cracked or busted cylinder wall.
yes you can have the block sleeved, but having more than two sleeves per cylinder bank on blocks that are not factory designed to have self supported individual cylinders generally results in a weaker block.
filling the lower coolant passages up to the level of the lower freeze plugs has a minimal effect on cooling but it reduces the UN-supported length of the cylinder walls making them stiffer.
KEEP IN MIND THAT YOU CAN PURCHASE BOTH NEW AND USED OEM AND AFTERMARKET CYLINDER BLOCKS, SO YOUR NOT STUCK USING, YOUR ORIGINAL PRODUCTION BLOCK WITH OVERLY THIN WALLS, IF ITS ALREADY RATHER THIN BUT REQUIRES A LARGER SIZE BORE

,

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bores must be honed with a deck torque plate to simulate the stress of a installed cylinder head stress , the torqued bolts exert on the bore walls, the torque plate induces and duplicates that stress so that the bore walls will be pulled into the same relationship when you hone the walls concentric, rings won,t seal correctly in a non concentric bore, aftermarket blocks with thicker and stiffer castings are less prone to bore distortion
a bit of reading here might be useful... get out a feeler gauge and look at how thick .060, .090, .120 actually is , and consider how easily a thin section of cylinder wall can flex and crack!
when G.M. or most manufactures "RATE" a block or any other component at lets say 350 hp what they are saying is that at that level of stress it should last a very long time, they are not suggesting that if its rated at 350hp, that at 360 hp its going to fall apart, only that the expected durability life span is being reduced, generally they build in some "cushion" usually 20%-25% or more because theres always going to be manufacturing tolerances and flaws
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when you have a block magnetically or dye checked for cracks , and sonic tested for bore wall thickness, don,t forget to check lifter bores, and lifter gallery areas, and main cap webs etc. just because its not easy to access does not mean cracks can be ignored
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viewtopic.php?f=53&t=3897&p=15720&hilit=hone+plate#p15720

viewtopic.php?f=51&t=125

viewtopic.php?f=51&t=7646

viewtopic.php?f=51&t=1014&p=1861&hilit=splayed#p1861

viewtopic.php?f=51&t=47&p=56&hilit=splayed#p56

http://www.hotrod.com/techarticles/engi ... omparison/

read this
http://www.project33.com/Categoryarticl ... ory=Engine
and understand its deck and cylinder wall thickness you need to verify more than core shift, its not the average cylinder wall thickness its both the MINIMUM and WHERE in the bore wall the thin section is that matters as the head bolts distort the bore, far more in some areas than in others.

(1) yes youll need to have the block under stress with bolts, or studs and a torque plate to duplicate the stress on the bore walls , that a clamped cylinder head induces on the bore walls to get the hone done correctly

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http://www.prostart.com.au/crisis/350chev/350-p3.html

http://racingarticles.com/article_racing-73.html

http://www.matweb.com/search/datasheetT ... =PDEVCON05

viewtopic.php?f=50&t=50&p=12527&hilit=studs+coolant#p12527

viewtopic.php?f=51&t=125&p=10122&hilit=sonic#p10122

viewtopic.php?f=51&t=11033&p=48899#p48899

viewtopic.php?f=51&t=3363

http://www.drillspot.com/products/31915 ... num_Liquid

viewtopic.php?f=51&t=7646

http://www.hardblok.com/product-info/

what does it mean to fill the block?

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http://www.caribbean.basf-cc.com/en/pro ... 85-Ing.pdf

heres a cross section of a block used strictly for drag racing with about 80% of the coolant passage filled, you can fill a block up to the lower edge of the freeze plugs and add significant support with only a minimal effect on cooling as about 90% of the heats generated in the cylinders upper 2.5" of bore

Ive also seen guys forget to install a plastic or metal tube in the lower coolant passage to allow the block to drain when they partly fill blocks to add block rigidity on thin cylinder walls, so remember to do that if your filling the block to increase cylinder wall strength up too the lower edge of the freeze plugs as forgetting thats a common new guy mistake

on most cars used on the street your limited too filling to the bottom of the freeze plugs

Filling a block is when you use a concrete like substance fill, that you pour into the water jacket of your motor.
The idea is to strengthen your block from the inside.
One of the main benefits is to control bore flexing.
Most people do two different types of fill.
1. Street fill-you fill up to the bottom of the lower freeze plugs.
2. Race fill- you fill to the bottom of your water pump holes.
All fills should be done "Before" you do your machine work.[/color]

ok, generally you want an absolute minimum cylinder wall thickness, on a stock production block of .180 and .230 or thicker is generally considered to be ideal, anytime your bore reduces the cylinder wall thickness below .200 in my opinion, if you intend to race the engine, you should fill the block to the lower freeze plugs with a block coolant passage filler to reduce the unsupported cylinder walls tendency to flex, which reduces ring seal., and generally the semi-safe limit, with the block filled is at about .200-.180, below that, wall thickness, becomes a potential major problem and the blocks life expectancy, is usually lower,
Id reject a block as a race engine if the upper cylinder wall thickness is under about .145" as an absolute minimum,and only go below .180 if that thin wall area is supported by block fill now Im sure youll find guys who have raced thinner cylinder wall thickness, but its pushing your luck.
A great deal of the engines heat is produced in the cylinder heads and upper 2" of the cylinder bore, and very little comparatively in the lower engine so filling the coolant passages up to the lower edge of the freeze plugs has a minimal effect on cooling if you've got a good radiator and water pump ETC.you check this with a sonic tester AFTER FIRST verifying the TESTER accuracy on parts of the engine you can verify with a caliper.

you certainly don,t want to dump bunches of cash into a block that will likely crack if subjected to the stress of racing!
IF your a bit under that .180 minimum, you generally strengthen the cylinder wall by filling the coolant passages in the block surrounding the cylinder wall up to the lower edge of the freeze plugs with a block filler, I prefer a slurry of about 85% steel shot of size .180" -.200", and 15%- epoxy block filler , if you use more epoxy the epoxy won,t expand at the same rate as the block when its hot, filling the lower cylinder wall coolant passage up to the lower edge of the freeze plugs has little effect on cooling,because about 90% of the heat is generated in the top 3" of the bores stroke and heads (JUST REMEMBER TO INSERT A DRAIN TUBE SO THE EPOXY DOESN,T BLOCK THE BLOCK COOLANT DRAIN PASSAGE ON EACH SIDE)
SUMMIT SELLS G.M. BLOCKS you can use to build a 383 for $700 plus shipping , but ID suggest limiting power to about 500 hp with these
http://www.summitracing.com/parts/sum-150100
I personally thing anything less than .145 is pushing things even WITH a partially filled coolant passage area, ask
your self a couple questions, have you got a written quote on the required machine work? have you had the block walls sonic thickness checked, and found out what the bore walls remaining thickness will be after being bored and honed at both the top and bottom of each cylinder wall at every 90 degrees?
how much money have you already sunk into that block in machining costs, or what it the likely cost of a line hine, bore job , maybe adding splayed man caps and having the decks trued up and how much more cash with getting the stock block prepped correctly cost, will you waste that money , what if the block cracks after you get it assembled and start running it?
I think almost all of us start out making the same mistake of trying to get the block we already own re-machined to save costs ,not realizing in most cases its wasted effort and cash.
you could very easily dump $800-$1200 IN MACHINE WORK ON AN OEM BLOCK, AND STILL HAVE A VERY WEAK BLOCK CASTING,THATS FAR MORE LIKELY TO CRACK AND FLEX, IN COMPARISON TO A DART, or world products BLOCK.
if you spend roughly $1500 on a much thicker dart block you won,t be nearly as likely to have block failure related problems.
OR you can spend a bit more and get a far stronger and thicker DART BLOCK casting for about $1550.
yes $1550 or so is a LOT of money,and I know how difficult coming up with cash is! but this is NOT a cheap hobby and if you put $800-$1200 in an OEM block the fails and trashes the rest of your parts you hardly save any money

http://www.summitracing.com/search/prod ... e%20Blocks

http://www.precisionreloading.com/steel_shot.htm

(#4 or #2 shot, or BB size preferred) buy the 40lb bag

http://www.ballisticproducts.com/Steel- ... info/SH04/

there are several block fill products that are basically high strength mortar or concrete

http://www.hardblok.com/

http://www.labsafety.com/Magnacrete-Con ... _24531183/

is popular, for filling blocks up to the lower edge of the freeze plugs

Ive used a slurry of steel bird shot and liquid EPOXY for my blocks

http://www.precisionreloading.com/mm5/m ... STEEL_SHOT

http://www.alvinproducts.com/Products/Products.asp?id=1

but almost everyone uses moroso concrete/grout mix as its readily available, this generally has very little effect on the cooling as most of the heat is generated in the heads and the first 2" of the upper bore of the cylinders.

http://moroso.com/catalog/categorydispl ... Code=22008


BTW you generally fill the coolant area BEFORE the BORE/HONE WORK

http://www.ndtsystems.com/Automotive/automotive.html

http://raceology.com/2004/11/sonic-test ... y-how.html

http://www.geinspectiontechnologies.com ... index.html

http://www.qualitest-inc.com/2000b-utg.htm

http://www.popularhotrodding.com/engine ... index.html

http://www.qualitest-inc.com/pr-82.htm

http://www.popularhotrodding.com/tech/0 ... index.html

http://books.google.com/books?id=-csSm0 ... q=&f=false

http://www.checkline.com/sonic_testers/

http://www.racecarmagazine.com/Articles ... .asp?ID=26

http://raceology.com/2004/11/sonic-test ... y-how.html

http://www.abqindustrial.net/store/soni ... -c-40.html

http://www.dakotaultrasonics.com/

viewtopic.php?f=51&t=10472

This is where the aftermarket performance engine blocks generally have a huge advantage over the standard production blocks, core shift and casting thickness is generally much better controlled on the better aftermarket performance engine blocks like DART sells as an
EXAMPLE
.

and yeah! at first the $1500-$3000 for a block seems absurd,
but it comes machined if you order it that way, (EXTRA COST OPTION IN MOST CASES) and its a whole lot stronger,stiffer,thicker and less likely to self destruct under hard use than a factory block., and its NEW not something that's been sitting around rusting and being over heated for 30-40 plus years, like some sbc cores, and the dart block cylinder walls can easily be twice as thick or more than a Chevy block and made from better materials.
here is where you, or your machine shop can screw things up on ring to bore seal, when you hone the bores,get and use block deck hone plates, during the hone process , keep in kind you want to use the same (STUDS OR BOLTS) the machine shop used and the same torque settings they used when the cylinders were honed with deck plates or the distortion of the bore and ring seal won,t be identical (exactly round)or ideal , aftermarket blocks can and usually do have significantly thicker cylinder walls, the thicker the cylinder wall the less the distortion , that effects ring seal will tend to be,under the load the bolts or studs used to fasten the heads to the block produce which will tend to distort the block

STEEL SHOT GUN PELLETS AND EPOXY WORKS AS A COOLANT PASSAGE FILLER
http://easy-strike.com/prod_liquid.html

http://www.adperformance.com/index.php? ... 82_105_309

http://www.adperformance.com/index.php? ... =69_82_106

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

http://www.scatcrankshafts.com/PDFs/ScatWorld.pdf

http://www.arengineering.com/articles/sonicbig.html

http://www.hotrodpitstop.com/engine-block-prep.php


http://www.e30m3project.com/e30m3perfor ... sonic2.htm
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: Engine Block Cylinder Wall Thickness

Postby grumpyvette » January 10th, 2009, 9:31 pm

If your looking for a block to start with you'll generally want to look for a 4 bolt block, as they tend to be slightly stronger than the two bolt blocks,IN MANY CASES BUT NOT ALL,OBVIOUSLY 4 studs or bolts SHOULD provide greater clamping strength than two bolts or studs but the thickness of the block web area varies a great deal, and just having 4 bolts is no guarantee its stronger, unless you add splayed main caps to the two bolt blocks, but ANY production block is significantly weaker than the bowtie and DART BLOCKS available know.Ive long ago lost count of the guys that dumped weeks of work and hundreds ,sometimes THOUSANDS of dollars into converting stock engine blocks to 4 bolt main caps or splayed main caps or had the blocks decked and line honed or bored cylinders, and honed ,or sleeved and then were forced to throw all that expensive machine work in a dumpster when the block cracked under use.
the stock blocks are designed for about 350-400hp and under 6000rpm, and while we all know guys who have built successful engine combos making a good deal more power the fact is the blocks significantly weaker than a DART AFTERMARKET block thats both a good deal thicker and has a stiffer and stronger alloy in the casting.


HAVE THE HEADS AND BLOCK CHECKED
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RELATED INFO

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most SMALL BLOCKs can be bored .030-.040, after that they tend to get rather thin in places, BIG BLOCK blocks will go .060 with no problem, some few will big block castings will go 0.100 and but you cant make a blanket statement because there are some blocks with core shift or just not enough material that are too thin to start with. if you are going to sink a lot of money in a block and machine work, and if you plan on making a lot of power you need to have the block sonic checked, and in almost every case if your goal exceeds 550 hp the DART aftermarket block is preferred as its got a much thicker casting,
IVE HAD EXCELLENT results with standard 4 bolt blocks from the late 1968-72 time frame, we bored them to 4.310 without thinking twice, (.060 over size) IVE built engines that exceeded 650hp, with 4.25" stroker cranks and 13.7:1 compression ratios,that ran on only race gas, but those blocks are now 35-40 years old and who knows what the coolant passages and stress levels have been subjected too, the DART aftermarket and BOWTIE blocks are significantly thicker and stronger castings than any of the standard production car blocks, and machine work is expensive, if you are thinking of exceeding 600-650 hp you'll be better off buying and using a decent aftermarket block as they are significantly stronger and thicker castings , thicker decks, thicker webs thicker cylinder walls, etc, priority oil passages,etc. they are made from a better alloy and less likely to have problems
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AFTERMARKET BLOCKS LIKE DART PRODUCES HAVE FAR THICKER CYLINDER WALL CASTINGS
http://www.dartheads.com/products/engin ... ig-blocks/

http://www.adperformance.com/index.php? ... =69_82_106

viewtopic.php?f=51&t=588&p=764&hilit=sonic#p764

http://www.arengineering.com/articles/articleframe.html

http://www.arengineering.com/articles/sonicbig.html

http://www.ndtsystems.com/Automotive/automotive.html

http://www.testequipmentdepot.com/reed/ ... 2a058b0ec6


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(this link below suggests a 0.125 cylinder wall thickness as a absolute minimum, on a high performance application, while 0.180, is what most shops suggest, as a safe lower limit on a race engine)
http://books.google.com/books?id=_i_XVV ... q=&f=false

well worth reading thru

have the block sonic tested, if you've got any doubts and have it honed with a deck plate, as a general rule cylinder wall thickness should ideally be a minimum of .200-.250 thick, getting much thinner,due to boring it larger, allows too much distortion for proper ring seal, and yes we all know guys who get away with .180 occasionally, but remember just because something, sometimes doesn,t fail the first few dozen or even the first few hundred times, its used, doesn,t mean its operating correctly, Id suggest getting an aftermarket block if you want a larger bore, and your pushing those limits on a stock production block, simply because the decks and cylinder walls are significantly thicker and the basic casting design is stronger, and if the stock casting fails at high rpms you might loose all your components, machine work, etc, certainly making the up front higher cost of the aftermarket block looking far more reasonable if looked at in that light.

the stock OEM components are rated by chevy, to with stand 350-400hp and 5700rpm-6000rpm,obviously we all know guys that have pushed their components to exceed those limits, but stress is cumulative, and the harder you push or the more frequently you push past those limits the more likely you are to experience component failures
look at the rated hp

http://www.sallee-chevrolet.com/ChevyBa ... 05123.html

the DART SHP Chevy Small Blocks are significantly stronger castings in the stressed areas and are rated UP TOO 600hp, the little m blocks are even stronger

http://www.dartheads.com/products/shp-c ... locks.html

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

it would make very little sense to build an engine thats intended to produce over about 500-550 hp on a STOCK PRODUCTION Chevy block simply because the main caps will walk or the lifter bores will crack or the cylinder walls will begin to flex ETC. at some point, and that point will be noticeably lower in the power curve than an aftermarket block , thats been properly machined, Ive got splayed 4 bolt main caps and use all ARP hardware in my block and Im still reluctant to push it much past those limits, because I see the results far to often in my shop, when guys insist on spinning the nearly stock engines to 7k plus or dropping a 150-200hp worth of nitrous,or use of stock bolts on an engine without the proper mixture and ignition controls and all forged components.

Image


a reasonably common result of boring the block walls too thin to support the rings, especially without partly filled water jackets on an OEM block bored more than .060 oversize, or if you fail to sonic test the block wall thickness, but keep in mind a rod letting go, a failed rod bolt or a piston destroyed by detonation could result in similar damage


an example of a sonic test on a stock block bores .060 over bore


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notice several areas, A-E where the block walls less than .100 thick




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sleeving the bore,some times its the only way to save a block, but your very unlikely to need this type of work on a well assembled DART or AFTERMARKET BLOCK, all these examples were bored to under .100 thick


theres hundreds of ways to destroy an engine, but a common route is trying to compress solid objects in the combustion chamber,where theres not nearly enough clearance,or having the valve train bind up due to clearance issues or reveing the engine above its valve control limitations.
failure to keep the pistons from hitting the valves, bending valves, ,over reveing the valve train and having un-controlled valve movement, or having chunks of piston,that detonation can break loose, being compressed against the heads,can result in the cracked cylinders, and bent rods like the pictures below show
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the crank or block can have the correct bearing clearance but still be slightly bent or the block may be warped and result in the bearing wear , keep in mind main bearing caps can crack or be improperly machined, this is FAR less common on DART AFTERMARKET BLOCKS
I think the 400 SBC 4 bolt blocks have a bad reputation that's probably not fully deserved , the rumor is that the web area of the block is weaker and the outer bolts further weaken the block, but I think its more a case of the extra bolts don,t significantly add to the block rigidity .
the 350 and 400 SBC OEM production blocks were designed to handle 350-400hp max,and when pushed well past that stress level its just logical that they occasionally fail.
if a two bolt block fails the normal response seems to be that
'we should have installed the angled aftermarket main caps'
if a four bolt block fails the normal response seems to be that
'we should have installed the angled aftermarket main caps, because the damn four bolt blocks weaker'
the truth is that by the time your making 500hp neither block with stock main caps keeps the main caps from moving under full loads and adding the splayed main caps while helpful is not a cure, its a band-aid at best, the aftermarket DART block has much thicker castings in the block web area and better and stronger alloys used.


http://webtools.delmarlearning.com/samp ... _ch139.pdf

http://www.thirskauto.net/BearingPics.html


Neither plastigage or a full set of micrometers or other ways of checking crank to bearing clearances will detect a bad align bore or a crankshaft with runout.

But there are some simple ways to check both.

http://www.herboldracing.com/2010/02/19 ... ank-runout

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Here are a set of main bearings that 400 miles o them and you can see there was an alignment issues the rear main bearing is missing but was in good shape.



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failure to check for cracks or use of a O.E.M. block at power levels its not designed for can and frequently does result in engine failure, most O.E.M. SBC blocks are rated at no more than 400hp, we all know guys pushing them to 500hp but much beyond that its a crap shoot and the blocks eventually going to flex and fail.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
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Re: Engine Block Cylinder Wall Thickness

Postby grumpyvette » March 22nd, 2012, 8:51 am

Racing Articles
Sonic Testing - What, Why, How
by Don Terrill ©2004

In the racing world a sonic tester is used to measure the thickness of metal in areas that can t be accessed for direct measurement, the most common being cylinder walls and roll bar tubing. For this article I m going to focus on the engine block s cylinder walls.

Relative to the induction system, there isn t much power to be had in the short block, but one of the most important areas is ring seal. The interaction between the rings and the cylinder wall is critical. Rings can handle some irregularity, but there is no question, the better the cylinder wall, the better the power.

How a sonic tester works:

Just like a bat or a radar gun, the sonic tester sends out a sound wave and then calculates the thickness of the metal by measuring the time for the reflected wave to return.

Calibration is the key to accurate readings. For the best results you should find two pieces of like material (cast iron), one thinner than typically readings and on thicker, to use as standards. You need to be able to physically measure these pieces and then compare them with the tester to make adjustments. You can try to find areas on the block for calibration or take a sledge to a blown up block and make your own. I was “lucky” enough to have a customer forget to put antifreeze in his block over the winter, which supplied me with the perfect donor block.

Where to test:

Major thrust â Located opposite the rotation of the motor. Facing the front of the engine, if it turns clockwise, the major thrust is the left side of each bank (V8). This is the location of the largest loads and thus it would be nice to see the thickest cylinder walls.
Minor thrust â Located opposite the major thrust and on the same side as the rotation of the motor - Typically the right side of both banks.
Front and back of block â This would be the front of the front cylinders and rear of the rear cylinders. Most manufacturers put a good amount of material in these areas, probably because they had the room.
Between cylinders â This is typically the thinnest section of the cylinder because of closeness of adjacent cylinders and the need to allow room for coolant. I ve actually seen blocks run with less than .100 on the pin sides.

What s a good thrust side thickness? .300+
What s ok? Over .250
What s bad? Under .200 on a thrust or under .100 on a pin side â I d call this a nightmare

What can go wrong? Egg shaped cylinder walls and worse, a cracked cylinder wall. A good way to know how good a block is without a sonic tester is to see how out of round the cylinders get after a season of racing, good blocks will take next to nothing to clean up, bad ones may take .002+ every season.

Fixes:

Grouting the block - Filling a block with grout is no replacement for having a good block. Grout can be helpful, but for other reasons that I will discuss in a future article.
Sleeving the block - There are so many things that can go wrong with sleeving a block that it s not worth the risk in my opinion.
Offset boring â Offsetting the boring bar away from thin spots may help a fuzz, but unless you re doing a large overbore you just can t make enough difference.
A better block â In the end this is the only true fix, with a few more pounds on the nose of the car being the only negative.
IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
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Re: Engine Block Cylinder Wall Thickness

Postby grumpyvette » May 28th, 2012, 9:05 am

just for grins IM posting this info to try to show why you don,t want to use a OEM 400 block thats been improperly machined.
in this case a guy on a different site posted pictures of what the result was when he used a stock OEM 400 block that had been bored .060 over size and honed without deck plated during the hone process.
this guy put hundreds of dollars into block machine work , and while tightening the head bolts he heard a (POP SOUND) and the torque changed, inspection showed the bolt tension caused the thin block casting that was bored .060 over size to crack.
you could easily pay $400-$800 for a clean 400 block, and add another $500-$1200 in machine work, think about that, then think about the far stronger DART block cost, and its far less likely to have similar problems


Image
look closely the red arrow shows the threads were repaired with a heli-coil thread insert, while thats not necessarily a huge problem the CRACK that goes thru the STEAM HOLE (GREEN ARROW) IS POTENTIALLY A MAJOR ISSUE

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notice that the piston rings don,t show contact wear on the cylinder walls ,adjacent to the bolt holes (LOOK IN THE RED BOXES) where the bolts tension pulls the cylinder walls outward, this could be compensated for if the block was honed with deck plates in place but the cause is extremely thin and flexible cylinder walls, the correct route is use of the far stronger and thicker casting used in the DART aftermarket block

Ive got zero doubt that adding main cap girdle adds rigidity, You can certainly make a great deal of horse power, but the rpm level stress goes up rapidly past 6000 rpm, and Id point out that the block casting design is the key to strength, in many designs, EXAMPLE, an olds blocks main web strength is not noted as nearly as strong as some of the other engines, so no matter what you do your stock casting is not going to be as strong as a good aftermarket block, like a DART,splayed 4 bolt main on a chevy big block, or a cross bolted block like some fords, hemis and LS1-LS7 engines so Id still recommend staying under 6000rpm, and last time I checked theres no OLDS ARP,connecting rods with 200,000psi rated 7/16" rod bolts, think thru your component selection with the intended rpm range in mind, theres no reason to spin some engines to higher rpms that the designs made to safely operate at.


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look closely youll see the lack of basic olds main web thickness, to anchor the main cap studs is a potential problem

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JUST COMPARE TO A BIG BLOCK CHEVY

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JUST COMPARE TO A CROSS BOLT FULL SKIRT HEMI BLOCK


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JUST COMPARE TO A mopar wedge FULL SKIRT girdle that uses all the oil pan bolts in the BLOCK

the better machine shops pin or sleeve the main caps to prevent movement
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Re: Engine Block Cylinder Wall Thickness

Postby grumpyvette » August 28th, 2012, 9:27 am

Indycars posted this great info



http://www.hotrod.com/techarticles/engi ... omparison/

If you look at the Chevy block on page 2, this is remarkably close to my experience. I bored a
350 in² SBC .060", which is .030" on a side. My thinnest wall was .064" on cylinder #4.

If the Chevy block in the Hot Rod (Page 2) article was bored .060" over, it's thinnest cylinder
would be .062".

Wish I would have known these facts before I spent $200 on boring a block I'm not going to use
for a performance application.

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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

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Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida

Re: Engine Block Cylinder Wall Thickness

Postby grumpyvette » May 30th, 2013, 10:55 am

I found these really rather good photos posted on the internet, of some of the machine work required for a well built engine
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splayed man caps on dart block
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honing lifter bores
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WELL HONED BORES TO QUICK RING SEAT LAPPING, and a good sealing surface
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BALANCING CRANK
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MAINS LINE HONED
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DECK PLATE HONE
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IF YOU CAN,T SMOKE THE TIRES AT WILL,FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK!!"!
IF YOU CAN , YOU NEED BETTER TIRES AND YOUR SUSPENSION NEEDS MORE WORK!!
grumpyvette

User avatar
Site Admin
Site Admin
 
Posts: 14105
Joined: September 14th, 2008, 1:40 pm
Location: florida


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