The original timing specification on the 327 would have been 4 to 8 degrees before top dead center, but that was before the cam swap. cammed-up small blocks like lots of initial timing, probably 12 to 15 degrees before TDC. The problem is when the centrifugal advance comes in, and total timing gets too high. With the vacuum advance disconnected and the engine running 2,500-3,000 RPM, the total advance needs to be 36 or 37 degrees BTDC, no more! You will probably need to find someone with a delay-flash timing light to set the timing that way, as the normal harmonic balancer doesn't have marks that far around it. Set the delay number to 36, rev the engine up, and adjust the distributor housing until the timing mark is on zero. If the timing at idle still doesn't suit you, you'll need to find someone with a distributor tester and the knowldedge of how to alter the centrifugal advance limits.
Jerry
