piston +.045 out!!!
 

my piston are .045 out im putting my e-head pumpgas 474 together & the block was deck't & line bored.it was a rotating assy.from my preveous motor that split up the mains.the block i have now must have been deck't many times before.my cometics are only .040 thick.should i order .060 head gaskets & mabey have the piston's cut .020 to give me at least .035 piston to head clearence.or order .080 cometics???

If that rotating assembly was balanced before I'd probably NOT cut the pistons.

If you choose to cut the pistons, make sure there is enough material to avoid cutting the piston tops too thin, enough material above the top ring and the notches are deep enough to avoid piston to valve issues.

i have about .220 thickness in the piston crown what would be too thin & what kind of distance(clearnce) should i run between piston & head at TDC.

Shaggy,I dont know about you blocks previous life but I just had a 100% stock original 400 block machined and they only cleaned up the deck at .006.When I put my assembly together with h-beam rods/ohio crank my pistons on average are .030 out of the hole-doesnt make sense with a stock deck machined only .006,anyway Im having to buy .065 cometics on mine as thats what the machinist reccomended for .035 clearence.I was palnning on using felpros and $220.00 later it sucks.

One other question,do your piston heights vary from bank to bank?-or are they all within a couple thousandths of each other?.Where did you measure them at the top/bottom of the piston or the sides?,thanks.

i measured from the center & tried rocking piston side to side i had 1 that was .036 two that were .040 & the rest were.045 out. i may go with a new cometic at .080.

I don't think it would be advisable to cut the pistons to get the .040-.050 you need to get for piston to head clearance. The pistons aren't extra thick now, so after cutting there will be little margin for error with timing, fuel ect.

Im no expert but I would think that would be the easiest and least costly solution to wind up with the right clearence.

If you go with something like the .080" Cometic gasket, try to get gaskets with bores very little larger than your cylinder bores, to avoid excessive "dead" spaces which contribute to detonation.

If you cut the pistons, don't spray it. I'd go with Cometics.

called summit today & they had the "TITAN" copper gaskets in stock .093 $213.00

Sounds like the SCE "Titans" have gone up in price. Are those the new ones with the integrated "fire ring"?
Caution: Don't use alcohol to wipe the Titans clean- it wipes off the elastomer sealing rings!

no these are the reagular TITANS but i do like the desighn of the firering gaskets. how are ur TITANS holding up?

Sorry, haven't run it yet with the Titans.

Also- I assume your block or heads aren't machined for O-rings? My personal preference (many different opinions on this) is to not depend solely on a copper gasket to seal compression. I've successfully used a half-fast (say that fast!) O-ringing approach, without machining for O-rings, by simply laying rings of .011" steel wire between the block and copper gasket. I overlap the wire ends about 1/2", and use contact cement to hold them until flipping the gasket over onto the block. This scheme worked for a season and a half of blown-alcohol competition- 10.0:1 400 c.i., 6-71 up to 12 PSI, to 8,200 RPM.

Why not buy the fire-ring style Titans?