C3 cylinder wall thickness quesiton-- Help!

[Travis_Williamson]

On a 1970 L-46, Does anyone know what the thickness of the cylinder wall is for the rear cylinders? Specifically the thickness of the cylinder wall at the very rear.

I also need to find out what the stroke length is?

If not, do you know where I can find out the specs?

Reason being is I accidentally gouged the cylinder wall (right behind the freeze plug) when trying to remove one of the rear freeze plugs and I need to see if this is going to be an issue.

Im sweating this one out.

Thanks
Travis

[Chuck R.]

Re: C3 cylinder wall thickness quesiton-- Help!

What did you gouge it out with? A drill bit? chisel? Punch?

How deep into the cylinder wall did you go and how large? Approximately

Chuck

[Travis_Williamson]

Re: C3 cylinder wall thickness quesiton-- Help!

Hi Chuck

I did it with a drill bit. I didnt even know I did it until I cleaned up the area. I dont know the exact measurements right now but its pretty significant, I want to say some where between a 1/16th and 1/8th of an inch. Its hard to say because its at an angle, almost like a v shaqpe if you were to do a cross section of it. Im hoping the wall is thick enough and that the gouge is far enough near the bottom of the cylinder I might be ok.

I have a photo but I cant post it right now.

Travis

[Joe L.]

Re: C3 cylinder wall thickness quesiton-- Help!

Travis----

First of all, the stroke for your engine is 3.480". It's the same for all 1969-96 350 cid Chevrolet engines and also the same for all 305 cid engines.

As far as the cylinder wall thickness goes, it's very hard to say. That's because there is often core shift when blocks are cast and the cylinder wall thickness varies from block-to-block. Also, cylinder wall thickness varies throughout the engine. Nominally, though, the cylinder wall thickness is ABOUT 1/4".

Look at it this way, though: 350 cid blocks, especially early ones like yours, can usually be overbored safely to .060". That represents about 1/16". So, if the engine has never been overbored and the "ding" on the outside of the cylinder wall is actually 1/16", then you should have no problem, at all.

[Gary S.]

Re: C3 cylinder wall thickness quesiton-- Help!

If the gouge is too deep, is sleeving an issue? No idea of the cost of a sleeve but if you really want to keep the block and that is the only cylinder that is bad, why not?

Gary

[Dick W.]

Re: C3 cylinder wall thickness quesiton-- Help!

You have to be careful with a sleeve. You have to machine the deck to get the top of the sleeve even with the deck.

[Clem Z.]

t******* the top of the sleeve

you can just trim of the top of the sleeve with the proper tool in a deck mounted boring bar,no need to deck the top of the block. just make sure if you sleeve the block make sure the shop knows how to "step sleeve" the block

[Travis Williamson]

Re: t******* the top of the sleeve

I will find out the exact measurement tommorow. I made a clay mold of it so Ill take it to work where I can have it precisely measured.

If I do need to get it sleeved I will definitely be taking the block to a machine shop, I definitely wont be doing it myself. I hope it does not come to this because with the exception of this there is nothing wrong with the motor. I only took it out to clean it and paint it so while it was out I decided to go ahead replace the freeze plugs.

This is one of those case where you make things worse by trying to do good.

Thanks for the inputs guys.

[Dick W.]

Re: t******* the top of the sleeve

Definitely step sleeve the engine. Sleeves look funny after, for whatever reason, move down into the crankshaft area

[Travis_Williamson]

Re: t******* the top of the sleeve

I did a clay mold and then measured the height of the mold on an optical comparator and the depth of the gouge is 0.0550".

If the cylinder wall is 0.25 I think it will be ok.

Any opinons or comments greatly welcomed?

[Mike McKown]

Re: t******* the top of the sleeve

That gouge with a drill bit in an isolated spot is a lot different animal than a thin cylinder wall, top to bottom. I'd put it back in the car and run it and never look back. You have little to lose at this point. No sense in wrecking your otherwise "good" engine for something that has almost no chance of causing a problem.

My opinion.

[Chuck R.]

Re: C3 cylinder wall thickness quesiton-- Help!

At.0550 your good to go Travis, button it back up and run it.

Chuck

[Roger Legge]

Re: t******* the top of the sleeve

I would take the block to a reputable machine shop and have it sonic tested for wall thickness before I'd consider sleeving it. Chances might be good that it's fine as is.

Roger