The Stovebolt Site Forums The Shop Area Engine Shop piston oversize

I had a friend of mine e-mail me some pictures of markings on top of the pistons of a chevy 261. Is the 90 on top of the piston an oversize? I thought .090 over would be kind of an oddball oversize. Would it be a marking for .060 over
[IMG]http://i1168.photobucket.com/albums/r488/Boltergiest/261%20pistons/photo_zps59a40775.jpg[/IMG]
[IMG]http://i1168.photobucket.com/albums/r488/Boltergiest/261%20pistons/photo_zps59a40775.jpg[/IMG]

I have changed the links.

Why not measure them. even an inexpensive digital 6" caliper will give you the answer.

Even a 6" scale will give you an idea.

I think those are stock, they would have a . and an extra 0, like this .090, at least thats how they are on all of them I have seen, the ones I have in the garage are like that. (well .040, but you get the idea.) But the really best way would be to measure them.

Thanks brokenhead. I agree with what you say. I have never claimed to know everything, but all the oversize pistons I have seen are usually marked as you stated. I would measure them myself, however my friend is on the other side of the state, over 3 hours drive time away

I'm curious as to why you need a friend to measure pistons? If you don't have micrometers look at Shars tool company, I got a set of 1-4" for an incredibly cheap price. I realize it is probably chinese, but for as much as I use them it is fine, and as far as I can tell they are dead accurate. you can spend a $1000 on a set of starret if you would rather, but if you are going to be fiddling with these engines you should have a set of precision measuring tools of some sort.

I don't need anyone to measure pistons for me. The guy popped the head off a 261 he bought, curious as to what the cylinder walls looked like. He does not have the tools, equipment, or knowledge to rebuild an engine. When he saw the 90 on top of the pistons, he assumed it was .090 over. He emailed me photos because I told him .090 over seemed like a rather oddball oversize. I posted the pics to see if there was anyone familiar with the markings on top of the pistons, thats all.

oh I see