Compression Ratio with pump gas??
 

What is the max comp. ratio if I still wanna run pump gas??

I have ran 11 to 1 with premium gas with no issues. Most will tell you that's too much and maybe it is...but I got away with it.

I am the same as TOD running 11.0 to 1, but 10.5 is a safe number to shoot for.

compression ratio-pump gas
 

I have a 355 sbc with 10.5 flat tops. It previously detonated when I ran some old steel 64cc turbo Chevy heads, #340292. We replaced them with a set of 68cc AFR alum heads with 180 runners and the detonation went away. I don't know if it was more from the larger chambers or the alum head material, but I suspect it was more from the aluminum since it dissipates heat better. It's may be easier and cheaper to swap heads than pistons. JMO Mep

let me rephrase...mine was 11 to 1 on paper, I never measured anything and did the math. It was a flat top piston 406 with 5.7 rods and it had a small hyd cam .507 lift dur @ .050 was about 244 I think. It had a set of the original sportsman cast iron heads with 64 cc chambers( advertised I didn't measure them)

is there any way to measure comp. ratio with the engine in the car???

NO

Oh, Boy :!: :lol:

are we going to use that magical compression guage again!! :lol: :lol:

I almost went there but decided against it...lol