Quench ???

[BW51]

Rebuilt my engine and dont like this. PLEASE HELP
sb chevy 350 bored .030
I have .028 clearence between the piston and head and really think it is pushing the limit.
Eng spec:
Icon forged light pistons @ 440 grams
Eagle H rods 6.0 inch
H bearings
Bowtie heads cast iron
Scat crank
Block is .013 under piston ( piston is coming out of cylinder)
I used old 1003 felpro head gasket and measure it with clay. Plenty of valve clearence .200 int and .190 exhaust.
Is .028 to tight to run ???/
asphalt track with 7000 rpm rev limiter 3/8 mile.
HELLLLPPPP any sugested ????

[NAYRBNYLF]

Try a thicker head gasket , it that a dome piston?

[stockcar5]

To tight IMO. I dont like to go below .035.

[fastford]

you can get MLS ( multi layer) gaskets up to .060 thick, those felpro,s are probably around .030 compressed. ive done this several times and never had a problem, however I don't like the piston coming out of the block, I does promote detonation, but sometimes you cant help it.

[keeks]

You need to be .035 to .040". You can maybe get a little tighter but you'll need a very high quality rod. Piston rock in the cylinder will be a factor to consider.

[lilsumo]

The 1003 is .041 compressed.

You need .040 quench so you need a .053 thick head gasket. Cometic makes one that is .051 and .056. I'd grab a couple of the .051 and let it ride.

[BW51]

The pistons are flat top 2 valve relief.
How much does the bore size lower compression. Cause most of those gaskets the bore is more like 4.200 instead of 4.165. Will it make a big difference. I see the volume measurement changes by 2 points or better.

[fast_crew]

Did you have .013" with piston square in bore or rocked over measuring to highest point? Should be measured square in the bore.

[lilsumo]

Using what I know from your engine, and assuming your heads are 64cc, a .051 head gasket, and 4 cc for your flat top pistons with .013 popup the results are as follows.

Head Gasket bore

4.060 CR 10.61

4.165 CR 10.56

4.200 CR 10.51

As you can see, not much difference, but there is some, so if you have a compression rule, you can fine tune.

[let-r-eat]

Too tight. Will hit head!

Take no chances. There isn't enough difference in performance for it to matter.

[BW51]

going with the .051
THanks guys not worth taking a risk with very little difference .