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How common is a .055" OS 440 cylinder really too thin?
Posted By: BradH
How common is a .055" OS 440 cylinder really too thin? - 03/27/13 07:02 PM
I'm curious based on people's experiences w/ sonic-checking OEM 440 blocks how common it would be that taking one to .055" or .060" oversize would really be taking a chance w/ thin cylinder walls.
Both my current .060" OS rebuild and my backup-in-progress .055" OS were bored to those dimensions "due to circumstances out of my control" and neither were sonic-checked before that was done to verify wall thicknesses. As someone I used to hang out with a lot used to say, "It is... what it is...".
These are early '70s blocks (as is my last untouched core 440 block), which IIRC doesn't mean squat as far as whether the walls are actually thicker or not than any other generation of OEM 440 block. So it makes me wonder if I'm really playing Russian Roulette(sp?) with them making 600+ HP. Thanks.
Posted By: Thumperdart
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 07:09 PM
Spend the coin and sonic check it.............no other way of knowing.
Posted By: Cab_Burge
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 07:53 PM
Quote:
I'm curious based on people's experiences w/ sonic-checking OEM 440 blocks how common it would be that taking one to .055" or .060" oversize would really be taking a chance w/ thin cylinder walls.
Both my current .060" OS rebuild and my backup-in-progress .055" OS were bored to those dimensions "due to circumstances out of my control" and neither were sonic-checked before that was done to verify wall thicknesses. As someone I used to hang out with a lot used to say, "It is... what it is...".
These are early '70s blocks (as is my last untouched core 440 block), which IIRC doesn't mean squat as far as whether the walls are actually thicker or not than any other generation of OEM 440 block. So it makes me wonder if I'm really playing Russian Roulette(sp?) with them making 600+ HP. Thanks.
Probally not But you know the old adage about Murphys law, right 
I have seen more RB blocks break the main webs than split the cylinder walls when making bigger power than stock like your talking about
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:41 PM
Quote:
Spend the coin and sonic check it.............no other way of knowing.
Unfortunately, no shop that I know of in the general area has a tester and my budget doesn't currently include dropping $1K for a good one just for myself.
From what I can tell, the cheap testers I've researched need to have the bore probe "massaged" to even get a reasonable reading which has discouraged me from bothering to try one of those out, either.
Posted By: Thumperdart
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:46 PM
Where the hell do you live............
Then it`s a coin toss..........good luck.
Posted By: 80fbody
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:46 PM
I'm rolling the dice as well on a .060 440 block I have that's pretty fresh. Was a stock rebuild but now will hopefully be around 500hp-550hp when re-done. Crossing my fingers it will stay together for a couple seasons.
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:52 PM
Quote:
I'm rolling the dice as well on a .060 440 block I have that's pretty fresh...
Still looking for rings?
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:55 PM
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Where the hell do you live...
You'd be surprised... but the local machine shops haven't seemed to think they need to invest in a sonic checker.
I'd probably have to drive a couple hours away to find someone with one, which starts to increase the PITA factor significantly. 
Posted By: Thumperdart
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 08:59 PM
Quote:
Quote:
Where the hell do you live...
You'd be surprised... but the local machine shops haven't seemed to think they need to invest in a sonic checker.
I'd probably have to drive a couple hours away to find someone with one, which starts to increase the PITA factor significantly.
No I wouldn`t........... 
I`ll take the "drive" PITA over the "guess it`s too thin" PITA any day.............
Posted By: an8sec70cuda
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 09:14 PM
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Quote:
Where the hell do you live...
You'd be surprised... but the local machine shops haven't seemed to think they need to invest in a sonic checker.
I'd probably have to drive a couple hours away to find someone with one, which starts to increase the PITA factor significantly.
It's the same way around here, but I got lucky and found a shop (Naylor's Racing Engines) a little over an hour away that could do it. They had to find their sonic checker first, lol. He said they never use it anymore since all the blocks they build (mostly BB chevy Dart blocks, etc.) are aftermarket and never have any issues. Charged me $40 to check it.
I called several shops and noone had one or could even tell me who to go to...even called PAR and Gene Fulton's.
Posted By: HPMike
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 09:28 PM
Hmmm
A sonic tester is pretty much standard equipment for any competent machine shop. I would think if you had a boring bar you would almost have to have a sonic tester.
Anyway. I sonic test all race builds and some street builds that are going oversize more than what is generally accepted. Many Mopar big blocks are pretty thin. I have cracked a few cylinder walls on .055" blocks. If its a race only deal, then go tall fill. Otherwise check it out and use discretion as needed.
MB
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 09:37 PM
The .060" is simply going back together w/ a ring & bearing job since it checked OK (no cracks, etc.)) at the last inspection. I'm just band-aiding it to get the car back on the road... more or less.
The pi$$er would be if the .055" block was tested and turned out to be too bleepin' thin. Other than the final decking, all of the rest of the machine work (bore & deck-hone, install aluminum main caps, etc.) is already done on it. Gawd, I'd hate to find out it's just a boat anchor...
And I'd hate to blow it up, too.
Posted By: 80fbody
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 09:45 PM
Would doing a tall fill distort the bore on a prepped block? I'm only going to hone 3-4 thou on this block (0.058 now) but would certainly consider filling it; if it were to increase my chances on it staying together.
Sorry to hijack Brad.
Posted By: 64Post
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 09:59 PM
I sidestepped a debate with a guru on FBBO that says there are no problems “blind” (not sonic checking) boring a stock block to +.060,” and that any problems with a thin/weak cylinder would have shown up at +.030.”
Posted By: VernMotor
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 10:43 PM
Quote:
I sidestepped a debate with a guru on FBBO that says there are no problems “blind” (not sonic checking) boring a stock block to +.060,” and that any problems with a thin/weak cylinder would have shown up at +.030.”
Who ever said that is a dumb a$$
Posted By: scatpacktom
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 10:53 PM
I bought my own sonic tester and now that I have it I test everything. That said "ignorance is bliss" now I stress out over everything. Recently had a Hemi block that was killer on the major thrusts on one bank and just so so on the other bank. Then it had this one area way down low that measured .119 that is when you lay in bed at night and think.
Honestly, Brad talking about it here will get you nowhere, or worse than that Pee'd off and nowhere.
Get them tested and and make a choice OR Turn the key and forget about it.
Posted By: Dodgem
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 10:59 PM
I Always go .060 some have gone .100 never have checked one but maybe should down the road!
Posted By: AndyF
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:02 PM
I've sonic tested a lot of Mopar blocks and 0.060 over is pushing the limit a fair amount of the time. To have two blocks that are both good to 0.060 without the benefit of any sonic checking would be a stroke of luck.
Speaking of that, I have a really nice early 400 block that I spent a bunch of money on years ago. It had a lot of nice machine work to it and it was ready to assemble with a 499 sroker kit. I happened to buy my sonic checker around the same time as that shortblock was going together so I checked the 400 block. One cylinder was super thin at 0.075. So that block is still sitting on the shelf. I can't quite bring myself to tossing it, but I don't want to build it either. Maybe someday I'll sleeve it.
Posted By: DblOJoe
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:04 PM
Mines .060 and never sonic checked also but it don't make much power just a bracket car.
Posted By: fed
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:05 PM
Sleeve it!
My 340 have 8 sleevs!
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:07 PM
Quote:
I've sonic tested a lot of Mopar blocks and 0.060 over is pushing the limit a fair amount of the time. To have two blocks that are both good to 0.060 without the benefit of any sonic checking would be a stroke of luck.
Uuuuuuugggggghhhhh....
I may have located a close(r) shop w/ a tester (Seriously Phord people, unfortunately) and would like to have them check both the "done" .055" block and the one remaining standard core I have. The .060" block is already an assembled short block and it's not worth pulling it down for this, given it's intended to be an interim solution while I finish a fresh build.
Posted By: scatpacktom
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:28 PM
I like to sonic engines that have already been run too.
A little experience I had, I made a pass with the T/A and came back to my pit spot with no ill effects what so ever. Comes time for the next pass... LOCKED UP! Here I had a teeny tiny pin hole right in the middle of the bore. The block in the T/A sonic tested AWESOME with every cylinder over .200 and alot of places over .300, so there you go. Even when you think you're golden you still can end up with problems.
Posted By: evenflow
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:46 PM
Google mopar myths thin wall blocks
Posted By: Stanton
Re: How common is a .055" OS 440 cylinder really too thin? - 03/27/13 11:50 PM
Its not thin-wall blocks he has to worry about, its core shift. The walls may have been cast just fine but if the cores shifted during the process then you'd end up with thin walls once they're bored.
Posted By: HotRodDave
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 12:13 AM
Is there a standard every one agrees on that is acceptable? Mabey the differance in guys who say they test them and they are "all too thin" are just using a different standard of "OK" than the guys who say they are fine
I had a block tested to see if it was safe to go .090 (very early 318 block) and they told me it was over .250 at the thinnest spot they could find, of course it cracked and was no where near that thick in a lot of places when measured with calipers
Posted By: BSB67
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 12:21 AM
So....what IS it too thin, say for 600 hp? Thrust, non thrust, and at the pin?
Posted By: quickd100
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 01:58 AM
If I was building a stock block I'd still drive 2-3 hours to get it checked, Mr. Murphy and me go back a long way.
I've got a July '71 400 block with the thick main webs. It's never been bored, one bore sonic checked at .083, 3 other cylinders were almost as bad. It's currently a door stop.Dave
Posted By: moper
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 02:25 AM
Too thin is whatever breaks on you. It's all opinions on what is thick enough to live. I own a good tester and it's debunked everything that the "bibles" preached about factory blocks. In terms of "thick enough" for me - it's a minimum of .225 on the major thrusts, .175 on the minor, and .100 on the pin axis. Thicker IS better but trying to find everything at .250 or larger in every hole you better have a big pile of blocks to test. It may be better in the long run to use a milder rod/stroke ratio or shorter stroke and get a taller & more stable piston that loads the walls less too.
Posted By: AndyF
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 02:30 AM
Quote:
Google mopar myths thin wall blocks
Nice to see one of my old articles still floating around the web.
Posted By: loaderpro
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 05:52 AM
I have a 68 440 block that is .060 with the walls at .185 to 1.98 on the thrustside 3/4 filled, stge 4 heads, 1/2 inch crank, 7.225 long rods with a 14.1 shorty piston, that goes 8.80s at 7500 rpm in a 2700 lb car....You should be fine, but if you cannot sleep at night definitly have it checked. For a street car though I would not worry about it. Any machinist worth his salt would have noticed it on the load meter while he was boring/honing it.
Posted By: jyrki
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 09:02 AM
I think it's nice that people recommend sonic checking, but when you ask what is the limit when you should discard a block, it becomes much more quiet. I have never sonic checked a block before, but now have a 4.375" bore 400 that cracked one cylinder. There is about a two inch long crack in one wall next to the pin, I believe water entered the cylinder and broke the connecting rod. The block is fully race machined with aluminum caps etc., so if possible I would like to save it if it only requires one or two sleeves. But what is an accepted wall thickness? I think the engine will make about 700 hp when ready, it's a roots blown 400.
Posted By: scatpacktom
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 12:50 PM
Quote:
I think it's nice that people recommend sonic checking, but when you ask what is the limit when you should discard a block, it becomes much more quiet. I have never sonic checked a block before, but now have a 4.375" bore 400 that cracked one cylinder. There is about a two inch long crack in one wall next to the pin, I believe water entered the cylinder and broke the connecting rod. The block is fully race machined with aluminum caps etc., so if possible I would like to save it if it only requires one or two sleeves. But what is an accepted wall thickness? I think the engine will make about 700 hp when ready, it's a roots blown 400.
Why don't you sonic test your busted cylinder and share the results with us? That way we will know what not to do.
Posted By: 64Post
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 01:31 PM
Quote:
Quote:
I think it's nice that people recommend sonic checking, but when you ask what is the limit when you should discard a block, it becomes much more quiet. I have never sonic checked a block before, but now have a 4.375" bore 400 that cracked one cylinder. There is about a two inch long crack in one wall next to the pin, I believe water entered the cylinder and broke the connecting rod. The block is fully race machined with aluminum caps etc., so if possible I would like to save it if it only requires one or two sleeves. But what is an accepted wall thickness? I think the engine will make about 700 hp when ready, it's a roots blown 400.
Why don't you sonic test your busted cylinder and share the results with us? That way we will know what not to do.
X2. Some empirical data would be swell...
Posted By: Cab_Burge
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 05:52 PM
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 09:20 PM
I did a lot of Googling late yesterday searching for functional, yet "budget priced", sonic thickness testers and came away w/ mixed results.
The same stuff you can eBarf from China directly for under $200 can sell for about twice that much if you purchase it from a U.S. or Canadian vendor, yet I'm not giving anyone in China my credit card info...
Apparently the cheaper offshore testers can actually read fairly accurately on flat surfaces, but the issue is the probes they come with don't read curved surfaces accurately. And either there is no appropriate curved-surface probe available for those cheaper testers, or the cost for a probe that should work from a US supplier is more than the tester itself costs.
Some folks have been able to self-modify the supplied budget probes to read a curved surface, but others attempting to perform the same modification have said it simply effed up the ability to take an accurate and consistent reading.
Anything that's a known-to-be-good unit available from a US supplier is pushing (or exceeding) the $1K mark, which simply doesn't fit my budget.
Posted By: Stanton
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 10:01 PM
Quote:
but the issue is the probes they come with don't read curved surfaces accurately.
I know very little about these sonic testers BUT ...
I understand that a bore is round but it is straight up and down so read it that way.
Just how wide does that probe actually read ... it seems to me that it would only read an area the size of the probe itself, which isn't very large. So despite it being a curved surface the variance from that curve should be minimal. Hell, there's probably more variance from the courseness of the casting sand!
Posted By: Stanton
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 10:03 PM
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Loc: La Casa de Chaos!
Where the F&#@ is that? If we had an idea of where you live we might be able to offer a couple of alternative suggestions!
Posted By: Thumperdart
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 10:39 PM
Quote:
Quote:
Loc: La Casa de Chaos!
Where the F&#@ is that? If we had an idea of where you live we might be able to offer a couple of alternative suggestions!
That`s why I asked earlier.........
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/28/13 10:48 PM
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Quote:
Loc: La Casa de Chaos!
Where the F&#@ is that?
According to MapQuest, I'm 24 miles northwest of the official residence of the President of the United States of America.
Posted By: Stanton
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 02:08 AM
Quote:
Quote:
Quote:
Loc: La Casa de Chaos!
Where the F&#@ is that?
According to MapQuest, I'm 24 miles northwest of the official residence of the President of the United States of America.
Ok, great! Sorry, can't help ya.
Posted By: Mopar-Al
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 02:23 AM
wow, 24 miles from mr big ears? Kenya dig it?
Posted By: loaderpro
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 05:24 AM
My machinist tells me that .150 should would be his minimum, blower or otherwise. The weak spot in the chrysler blocks is in the webbing of the mains when you get into the 800 plus hp range.
Posted By: JohnRR
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 06:07 AM
Quote:
The .060" is simply going back together w/ a ring & bearing job since it checked OK (no cracks, etc.)) at the last inspection. I'm just band-aiding it to get the car back on the road... more or less.
The pi$$er would be if the .055" block was tested and turned out to be too bleepin' thin. Other than the final decking, all of the rest of the machine work (bore & deck-hone, install aluminum main caps, etc.) is already done on it. Gawd, I'd hate to find out it's just a boat anchor... And I'd hate to blow it up, too.
It's not a boat anchor , sleeve the thin bores .
I have in my possession a .040 over 69 block that has 3, or 4, thin walls, on the pin side, that are around .090. If I were to do anything serious with it, after I buy it of course, I would sleeve the 4 cylinders . 
Posted By: jyrki
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 09:18 AM
Quote:
Quote:
Why don't you sonic test your busted cylinder and share the results with us? That way we will know what not to do.
X2. Some empirical data would be swell...
I'm having the cylinders sonic checked, will publish the numbers once done.
Posted By: 440Jim
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 01:54 PM
I know Jan Norris at Precision Engine Machine in Hyattsville has a sonic checker and he knows how to use it.
I haven't talked to him in many years since he ~2000, so give him a call and ask. Attached are the numbers prior to boring 0.033" on my 400 block (511 CID, 4.250" stroke). As you can see the thrust are pretty good, and the thinnest front/back was 0.139", so ~0.122" after boring.
301-779-5808
The really hard question is what is good enough. They can crack on any surface, so although the major and minor thrusts should be the thickest, the front and back sides shouldn't be 0.080" thin either.
The block you have used before is likely good since it hasn't cracked from all that prior use.
Posted By: BradH
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 03:06 PM
Just got off the phone w/ C&C in Manassas and they want $175 to take only 4 readings per cylinder... Sounds really high to me, so I'm going to call some other folks (first anyone I can find in VA, then across the Potomac @ Performance Machine) to see what else I can find.
Posted By: 64Post
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 03:43 PM
Quote:
Just got off the phone w/ C&C in Manassas and they want $175 to take only 4 readings per cylinder... Sounds really high to me, so I'm going to call some other folks (first anyone I can find in VA, then across the Potomac @ Performance Machine) to see what else I can find.
Man, run away from that place... 
IMO, minimum should be 3 readings per axis per cylinder... that's 12 per cylinder X 8. That's what I got for $75 back in Denver...
Posted By: VernMotor
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 03:46 PM
I just had 7 blocks done 70-75 each 12 reading a cy
Posted By: Bigfury
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 03:54 PM
Brad if your really interested,the machine shop near me will give ya a better deal than that.Also knowing your about three and a half hours away. I also have a couple of blocks to have checked,should get a quantity discount.Could most probably schedule over a weekend.Least I could do for all the help you've provided.
Posted By: B G Racing
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 05:04 PM
If your dragging it to Pa. bring it buy the shop,we will sonic test it for you N/C.
Posted By: moper
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 05:41 PM
The transducer has two "feet" and they are machined for a certain radius. Mine is ground on a 4" which I think is fairly common and according to Dakota it's accurrate for most bores from 3" to 5". Because they are set into ceramic and precision ground the curve is very specific, and the calculations the unit makes includes those curves and distances between the "feet". You will get false readings trying to read without both "feet" flat against the surface. So you either get the transducer you need, or test it incorrectly. They make a variety of transducer shapes too.
The cheaper units are not accurate enough to provide the insurance against failure. They aren't worth the shipping no matter where they'r emade or shipped from. Look for one that comes certified and that is calibrated off the piece you're testing because cast iron varies tremendously.
Posted By: 440Jim
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 06:31 PM
Quote:
Just got off the phone w/ C&C in Manassas and they want $175 to take only 4 readings per cylinder...
Yea, $175 sounds high.
But the details of what they are measuring is worth talking to each shop. They might only write down 4 readings per cylinder, but hopefully (check) they will run the probe down the cylinder and record the thinnest area they see on each of the 4 sides. I have also heard of shops that take a reading 1" down and 3" down or whatever.
Posted By: ZIPPY
Re: How common is a .055" OS 440 cylinder really too thin? - 03/29/13 07:27 PM
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Quote:
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Loc: La Casa de Chaos!
Where the F&#@ is that?
According to MapQuest, I'm 24 miles northwest of the official residence of the President of the United States of America.
Dammit, I knew I should have looked you up when I was in North Bethesda 
Shame on me, my sonic tester battery was low and I didn't realise what it was telling me when it would flash and turn off 