Vega

Got another question for ya. Ive been looking for pistons for a while, just got a good deal on a set of used 455 pistons/rods from a 69' 455 (pistons/rods for $50) i know they're higher compression pistons, they have the two linear relief cuts in them (kind of a V shape) was wondering what CC these pistons might be so i can plug it into Summit's compression calculator and see where id be. The engine ive been working with is a stock 72' with Ga heads and rediculous bathtub-esque dished pistons (i could drink out of these damn things), my plan was to get the heads worked on, throw in some higher compression pistons and a bigger cam and have fun on a budget. The aftermarket pistons i have been looking at are around $350 so pistons of near the same CC for $50 (with rods) sounds like a sweet deal to me, even though they are cast, but that shouldnt really be a problem i dont think.

So yeah, just wondering about the CCs on the 69' heads and maybe some input on running them. Thanks!

J-(Chicago)

I think the piston dish is about 12cc, and the heads will cc around 79.

Vega

Well i feel like a moron, guess i should have searched the "tech" section before just posting a thread haha. the tech section says they should be 15.7 (calculated CC), or 15 (measured). Aside from those numbers ive heard J's 12 and an Olds builder near me guessed 20 haha. I think im going to calculate for 15 and work conservatively with my gaskets to make sure i dont over-compress

64Rocket

You need to "CC" the pistons to be sure. You also need to measure how deep the pistons sit in the block. The heads, if never been milled, you will have 80 CC's or more. So in short, you bought used pistons and use the "felpro" gasket that is .040 thick, you have not gained much. I say you need to deck the block, (after you measure the depth), .025 and mill the heads .025, be sure to "CC" the heads again, and now you are taking up the difference of the new head gasket. Now with the measurements, plug those into the calculator and now you have some idea as to what to do.
Another issue is, have any of the used rods have had a spun bearing, you should have them re sized

Gene
PM me if you need more info

Vega

Thanks for the advice 64Rocket, i have been doing my homework on this motor for a while though haha. My original idea was to buy some Keith Black pistons (i think they were 12cc) and assuming an 80cc head (ive heard give or take, but one or two in any direction shouldnt throw my end goal off too much), with a 0-deck block, and a .02 gasket i found on Summit, i was looking for 10:1-10.3:1

My estimations may be off a little its been a few days since i used Summit's calculator and i looked into a few combinations, but thats the jist of what i was looking for. As for rods i have 2 sets of those so unless 9 of my 16 turn out bad i'll be just fine haha. I do know one of the rods did have a spun bearing but its on my other set of 72' 40cc pistons. I plan to get all of this checked out, cleaned, and machined to however it needs to be, was just trying to get a ball park estimate of the 69' piston's CCs to try to toss it into Summit's calculator (there's always possibility of results verying one way or the other but im just trying to get a target to aim for and a game plan together right now) Thanks for the help!

Vega

Quick update on my compression idea:

My original plan was (with the aftermarket pistons): stock bore/stroke, 80cc heads, 12cc pistons, .03 deck (assuming the worst of the average), and that .02 gasket would hit almost right at 10:1

Now with the assumed (for now) 15cc pistons i can manipulate my formula by 0-decking the block and using a stock .04 gasket and again hit almost right at 10:1. Although i am tempted to toss the smaller gasket in there and see if i can skimp by on 10.3:1 haha

cutlassefi

Can't, with a 0 deck and a .020 gasket the pistons will almost certainly hit the heads.