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Discussion Starter #1 (Edited)
Hi, I couldn't find much info on this, forgive me if it's been asked before.. Is the skirt on a piston wider at the bottom than at the top? And is .002 too tight a clearance for ptw? If so could I hone the cylinders again to get a better clearance?

I got my 83 5mge block bored over to .020 and my pistons are very tight in the bores around the skirts. They go in easyish but I can't fit the .003 feeler at all in between it an the cylinder wall. I can baaarely fit the .002 feeler, and it only fits near the top of the piston skirt but the bottom of the skirt seems to rub the cylinder wall pretty tight, and only the .0015 feeler will barely fit, and I'm having to finagle it in there.

That's putting the piston in upside down. That's how I noticed it, checking ring gap, which is fine btw, the rings that came with the piston fall within spec as far as gap in concerned.

I was just wondering if it's normal for the bottom of the skirt to be that much wider than the top. It's like that on all my pistons, even my old ones are wider at the bottom of the skirts.

I just wanted to ask before I started putting the block together, I'd hate for it to seize up soon after the first start.. Thanks in advance for any help.
 

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A feeler gauge isn't the correct way to check this. You need to use a mic and bore gauge to measure this. You measure the piston with a mic and use the mic and bore gauge to measure the bore diameter and subract the two and divide in half. And yes they are usually larger around the skirt since that is where the piston rides.
 

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Discussion Starter #4
Thanks for the reply.

So even if I could accurately measure using a feeler gauge I would still need to divide that number by half, since a feeler gauge would only fit on one side with the piston pressed all the way against the wall on the other side. So that would make it only .001 inches. Not saying it's accurate but that's how it would go.

I'll have to get a bore gauge. I'm just trying to avoid going back to the machine shop, they've been such a hassle to deal with already. Don't really have any good shops around here. Not that I know of anyway.

Also I guess I should've mentioned my measurements are in inches. So .002 inches would be about .05 mm.

This is the first motor I've ever actually rebuilt. I trust myself to be able to do it, just don't have a lot of tools I should probably have for this kind of work.
 

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"This is the first motor I've ever actually rebuilt. I trust myself to be able to do it, just don't have a lot of tools I should probably have for this kind of work."
Well, to be fair, the tools don't come cheap as well. You may have to start buying them from reliable manufacturers who would give you better deals.
 
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