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 Piston question - how thin is too thin? 
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Joined: Mon Dec 29, 2014 1:26 am
Posts: 433
I have stock replacement cast pistons that need to have around .120" or so cut off the tops. This will leave the distance from top ring to piston top right at .125" thick. Is that enough to be safe?

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This is a round dish top, so the cut will not touch the overall top thickness, only the raised ring around the OD.

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Wed Sep 23, 2015 1:46 pm
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Joined: Thu Mar 28, 2013 6:09 am
Posts: 726
Back in the day I used a set of dished 5.7 sbc pistons from a late model that were dished and removed the dish to make them use able
in a 383 build. used the 5.7 rod with that combo. This was the only way that I could figure it out with out doing a custom piston price and it all worked out fairly well..Put over 50K on it and as far as I know its still running as I see it now and then..
I did use a forged aluminum TRW piston but I think a cast piston will be fine..
If I remember I used a thick head gasket and found a set of early smog heads with a large chamber like 76+cc to cut the compression down....Good luck :thumbl:


Thu Sep 24, 2015 6:12 am
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Joined: Mon Dec 29, 2014 1:26 am
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That's pretty much the same situation here. Engine is a 3.5" bore 267, and there are NO shelf pistons for that size of any type or money other than stock replacements with this full-cup head design. The 267 has always been a ping monster even though the CR is a dismal 8.2:1... because of having no quench. My solution, using parts already on hand, is to throw in a 3.75 stroke crank, then chop off whatever amount of piston sticks out the top. Using a 5.85" rod and the stock crank would come out about the same, but I already have the 383 crank ready to run.

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Thu Sep 24, 2015 12:38 pm
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Fri Sep 25, 2015 3:24 am
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Joined: Mon Dec 29, 2014 1:26 am
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So is there any way to get a flat top piston in here other than spending $900 for customs? To be clear, I don't care about using the 3.75 crank or anything other than getting a flat top with some functioning quench. A cast stock replacement flat top would be just fine but they don't exist.

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Fri Sep 25, 2015 3:28 pm
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Joined: Tue Jul 30, 2013 1:48 am
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What compression height do you need?


Sat Sep 26, 2015 5:04 am
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Joined: Mon Dec 29, 2014 1:26 am
Posts: 433
ASSuming this virgin block is 9.025", it'd take a 1.585 c/h to get zero deck with stock crank/rod. However, to confirm that I need to drop in one of these new pistons which I know for sure are 1.54" and see where they end up. The factory pistons still in the block are .030 down the hole at TDC but I don't know their actual c/h.

The only reason I'm considering using the engine at all is that it's super low mileage (around 26k in an honest-to-god granny car) and needs no machine work. I have several 350 blocks but they all need some sort of work, one needs a sleeve, another one needs the full bore/hone/resurface/line hone, etc. But, of course, fixing one of the 350s would be much cheaper than a set of custom pistons for the little 267. Doesn't make any sense to even mess with it if it's going to cost real money.

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Sat Sep 26, 2015 3:30 pm
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