Don Terrill’s Speed-Talk

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,

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

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.

falcongeorge wrote: ↑Wed May 20, 2020 12:58 pm When you say "front and back sides" you mean between the bores, right?

Correct.

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.

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

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.

I would love to have that block if I were to go .060" . You have plenty of thrust and that is the most important.

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.

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

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 .

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

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.