Ok here is the deal. I have 58cc chamber heads, -3.4cc pistons 4.030 bore, 0.039 headgasket.

Static compression ratio is 11.54:1 with a 4.025 head gasket bore (don't know the size of the fel pro gasket)

or 11.48:1 with 4.125

Using a dynamic compression ratio calculator with my stats and the cc306 (intake valve closes at 43* ABDC @ 0.050 lift) I netted a 10.53:1 dynamic compression ratio at sea level. That seems awfully high as I was told you move the decimal over to the right to figure your minimum octane requirement which would be 105.3 =/.

Please tell me im doing something wrong.

 

Don't use the IVC @ 0.05 lift, you should use the IVC @ advertised or 0.006" lift. Your DCR should be fine with that cam.

 

Ah, the calculators I was using required the ABDC at 0.05

DO you happen to have one that uses it at 0.006?

I got 73* ABDC at 0.006 = 8.57:1

 

Sorry, don't have any calculator, but the one you're using is ok, it only appears that they mistyped the lift figures. For DCR calculation you need to know the piston position when the intake valve closes and when there is good pressure in the cylinder. At 0.05" pressure is still bleeding and that can't be logically considered for such calculaton.

 

that needs to be a sticky! seems like we see the @ .050 #'s alot anymore...