Too Much Deck Height ??

[flmont]

The measurement on my 81 turned out to be 160 mm or 0.063..is it possible to have to much ?? its a stk set up at 60 Deg F and 2021 cams are being used so it should be safe right ??...TIA Frank

[Steve@Rennsport]

Hi Frank:

You might get several opinions on this but .063 deck height is FAR too much.

I shall assume that you are measuring this at the very edge of the piston just above the ring land.

You need to shim each cylinder up to .040. This helps prevent detonation by providing proper squish in the cylinder at TDC.

[flmont]

I truely dont see how this can be,. the heads were Mach.just enough to clean them up,..they should should be close,..I must have measured wrong.it is a bit chilly 60 Degs as I said,but can that effect my measuments that much...Thanks Frank

[cstreit]

Are you measuring all four sides of the piston?

They pistons can rock a bit in the bore as you press down on your micrometer and give false readings. Sometimes measuring both sides in the same axis as the wrist pins and averaging gives you a better measurement.

.063 is definitely too high... Max I would go for in a street engine is about .050

[flmont]

I dont see how its too high,..took it apart sent out the heads..the just cleaned up the mating surface started to re-assemble NO major mach work was done to the heads and the case was never apart go figure...Frank