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Cylinder wall thickness ,,, again :)

General engine tech -- Drag Racing to Circle Track

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BillK
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Cylinder wall thickness ,,, again :)

Post by BillK » Wed May 20, 2020 11:03 am

Hey guys,
I found a couple of old posts on the subject but figured I would add another one. I am working on a mid 90's Chevy LT1 block. It is .030 over now but has a little pitting in one cylinder where water got in from the head and they let it sit too long before taking it apart. I am pretty sure it will be ok at .035 but might have to go .040.

The cylinder walls have pretty decent thickness on the thrust side in my opinion. The thinnest one is .250 But I have one or two that are at about .100 on the front or back sides. Most of them are .120

Should I be concerned with the front and rear sides that much ? This is a naturally aspirated 383 and makes about 600 hp. 6800 max rpm. The block has had caps installed on it and some other work so I hate to tell my customer he should replace it but I would rather be safe than sorry. I am not building the engine.

Whats the opinion ?
Thanks,
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

mag2555
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Re: Cylinder wall thickness ,,, again :)

Post by mag2555 » Wed May 20, 2020 12:10 pm

Even at .120" I would want to do a half fill on the block.

falcongeorge
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Re: Cylinder wall thickness ,,, again :)

Post by falcongeorge » Wed May 20, 2020 12:58 pm

When you say "front and back sides" you mean between the bores, right? I like a half fill on everything, but I really wouldn't lose ANY sleep over .120 between bores.

BillK
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Re: Cylinder wall thickness ,,, again :)

Post by BillK » Wed May 20, 2020 1:02 pm

falcongeorge wrote:
Wed May 20, 2020 12:58 pm
When you say "front and back sides" you mean between the bores, right?
Correct.
Bill Koustenis
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Waldorf Md

www.enginerepairshop.com

falcongeorge
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Re: Cylinder wall thickness ,,, again :)

Post by falcongeorge » Wed May 20, 2020 3:06 pm

BillK wrote:
Wed May 20, 2020 1:02 pm
falcongeorge wrote:
Wed May 20, 2020 12:58 pm
When you say "front and back sides" you mean between the bores, right?
Correct.
Its fine, I wouldn't worry about it, and I wouldn't specifically do a fill because of .120 wall thickness between the bores, although there are many other benefits to doing a fill.

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Re: Cylinder wall thickness ,,, again :)

Post by allencr267 » Wed May 20, 2020 3:33 pm

How far down is it, far enough to leave it alone & live with it's affect/effect?

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Re: Cylinder wall thickness ,,, again :)

Post by BillK » Wed May 20, 2020 6:49 pm

allencr267 wrote:
Wed May 20, 2020 3:33 pm
How far down is it, far enough to leave it alone & live with it's affect/effect?
Its a little over an 1 1/2" down. I personally would not want the rings passing over it every rev.
Bill Koustenis
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Waldorf Md

www.enginerepairshop.com

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af2
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Re: Cylinder wall thickness ,,, again :)

Post by af2 » Wed May 20, 2020 7:47 pm

I would love to have that block if I were to go .060" . You have plenty of thrust and that is the most important.
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Re: Cylinder wall thickness ,,, again :)

Post by rustbucket79 » Wed May 20, 2020 9:27 pm

You're losing .005" wall thickness, if it fails at .040" it would fail at .035". I honed a stock eliminator LT1 a few years back, it was .060" over and working well. FWIW, the bores were as bad as .0015" out of round. Bigger on the non thrust position.

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Re: Cylinder wall thickness ,,, again :)

Post by smeg » Fri May 22, 2020 2:24 am

We hold our minimum to .080" for a stock to mild engine. Never had an issue in lots of years.

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Re: Cylinder wall thickness ,,, again :)

Post by Momus » Fri May 22, 2020 2:39 am

BillK wrote:
Wed May 20, 2020 6:49 pm
allencr267 wrote:
Wed May 20, 2020 3:33 pm
How far down is it, far enough to leave it alone & live with it's affect/effect?
Its a little over an 1 1/2" down. I personally would not want the rings passing over it every rev.
Lol mate :shock: :lol: :lol: .

Have a look inside a racing 2 stroke sometime to see what is a fair gap for a ring to clear.

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Re: Cylinder wall thickness ,,, again :)

Post by BillK » Fri May 22, 2020 6:42 am

Momus wrote:
Fri May 22, 2020 2:39 am
Have a look inside a racing 2 stroke sometime to see what is a fair gap for a ring to clear.
Yes but they are designed for it. They have chamfered edges on the ports and most likely the rings are designed for that purpose. The rings are pinned to they cannot turn and possibly have an end get in the port.

You are comparing Apples to Bananas.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

www.enginerepairshop.com

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