Questions about quench, dynamic compression, and 91 octane gas.

[glockr]

I got my cam today, Comp 20-629-5. According to the specs, intake valve closes at 45 ABDC. Heads are TF 190 with 60cc chambers, pistons are flat top with 5cc for the valve reliefs and block is .030 over and machined for zero deck height. When I run the numbers through a dynamic compression calculator with .051 head gaskets, I get about 9.8 dynamic compression. Will I be OK with that running 91 octane? If not I could use .070 gasket and get it down to about 9.3 dynamic. So if 9.8 is too high for 91 octane, would going to 9.3 be enough to run 91 octane w/o detonation? Is .070 still tight enough to be considered "good" for quench? Don't know how much it matters, but car is a stock 66 A body, 5 speed manual, 4.30 gears.

 

[autoxcuda]

I have a smaller comp solid (274-S) with 9.7:1 measured with edelbrock heads and .040 quench in a 416”

I run 91 octane California spec gas

I think you’ll be fine with 9.8:1

There’s a bunch of calculations, but they don’t take in account absolutely everything. You need to put it together and see what happens. You can fine tune with total and mechanical advance curves

 

[Mopar69gts]

Maybe try different dynamic compression calculator.
Some use advertised specs
Some use @50 specs
Some use @50 + 15
I'll bet you'll find your combo is under 9 to 1 dynamic compression.
My 340 has 9 to 1 dynamic
And runs on 91 octane...

Go fast math dynamic compression calculator uses @50 Ivc

 

[glockr]

Maybe try different dynamic compression calculator.
Some use advertised specs
Some use @50 specs
Some use @50 + 15
I'll bet you'll find your combo is under 9 to 1 dynamic compression.
My 340 has 9 to 1 dynamic
And runs on 91 octane...

Go fast math dynamic compression calculator uses @50 Ivc

Thanks. When I run it through that one it gives the same static compression but dynamic drops to 8.94, guess I can stop worrying