I have been a shade tree mechanic for about 40 years. Over the years I have found that older engines, or engines with a lot of mods (cam, intake, ignition) will not run properly with the original factory specs. Also, the fuels of today do not have the same octane as fuels from the 60's.

This said, I have found the best way to set the timing on a carb. setup is to hook up a vacuum gauge to your intake manifold vacuum. Next, start engine and at idle, adjust timing for maximum steady vacuum. Make sure you don't go to far, as the vacuum will become un-stabile if advanced too far. Once you find the max. steady vacuum, back off 2 lbs. of vacuum and lock down the dist.

I have found this method sets the engine where it wants to be, is very simple and no timing light required. After setting, drive and make sure your not getting detonation under heavy acceleration. If detonation is heard, retard timing slightly. If no detonation is heard, your done.