Piston identification

Firebolt

Well-known member
Hi, I took head off, and I can see 029-01-05-A in top of pistons. Can anyone tell anything from that? I tried google but didn't find anything.

They are dished pistons, not sure about overbore. Engine is 200 cid and rebuild before I bought it. Its been years so the person who did it doesn't remember. Cylinders are so good they don't even need honing, so before I start measuring, the numbers could possibly tell what pistons those are? Engine was running good, but I'm changing cam and need more compression so thought about using flat top pistons.

Thanks.
 
Hi, every oversized piston I've seen was stamped the oversize, like .010 or .020. Like wise, undersize bearings are marked. Good luck
 
Same with bronco on what I've seen for oversized pistons. I don't think I've seen numbers on stock pistons. Since the block is good I would leave that and pistons alone, look at having the head milled to up the cr it will be cheaper too. If you do that now would be a good time to port the head and install bigger exhaust valves. If you don't have it is suggested that you get and read the falcon six hand book.
 
I have had some problems with vibrations, and engine damper seems to be not so good anymore. So I thought I'll get new damper, mill head (another topic) and balance all rotating parts properly. I think they are not matched, but it will be tested. So flat top pistons would be good, cam is Clay Smith cams 274/274 (224/224 @ .050 lift).

So I'd use this basic recipe that has been in my car earlier: www.ponikorjaamo.com/ti80/gen2.htm

Only making it with EFI, different ignition and more modification to head. Or is it possible to get 9.5 CR with dished pistons? I think head needs to be milled too much for that. Maybe I'll just need to go and measure bore.
 
I'm at 9.45:1 with stock pistons. I have 48cc chambers and am using a gasket with a thickness of 0.035"
 
Thanks cr_bobcat, how much head/block have been milled?

I looked more of those pistons and there are 275P 030 marks too. At least I don't need to measure them since that 030 came visible, I don't have tools for that now. Does that 275P mean dish cc or something?

I'm still going to balance this engine, and check piston rings. When there's no need for new pistons I can use that money elsewhere.
 
If they were oversized they would be marked like this. Pic is from my 250 block.
 

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I had the head milled 0.070". I started by measuring the combustion chambers <- critical first step! My C9 casting log head started off with 61-61.5 cc chambers. I read a few articles here and figured out what to expect in terms of volume reduction per 0.010" of mill. My goal was 48cc chambers. I gave my machinist both numbers (what to mill and desired volume) and everything came out correct.
 
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