Re: HELP engine tune up advise needed 67 327
That sounds like a lot of compression. Have you done a simple cranking compression test? If you've got 200+ psi cranking then I would be gentle on the timing. I would suspect that your cranking psi would be around 170.
Timing is where I would focus. Make sure the distributor mechanism is all working. The mechanical advance mechanism should move easily and allow around 24 degrees of advance, in by about 3000 rpm. Set initial timing at 10 degrees advanced, for about 34 to 36 total at 3000 rpm or so. You can check this with a test light.
For more mileage, I would focus on the vacuum advance. I like to connect the vacuum to a port that HAS vacuum at idle. This way, you get maximum advance at part-throttle, but the vacuum will basically be zero at full-throttle so at that point you work off mechanical advance only.
Careful of pinging (aka: detonation). If you hear it, then back off timing.
Dave F. in Rhode Island
'68 Camaro SS Accel DFI 454 (SOLD - I'm a boring Corvette owner now)
Bought my first big-block Chevy in 1970