[olddog]

I don't know if you read the links I told you about, so I will explain one thing that may be important.

A lean fuel mixter burns slower. Richer mixtures burn faster. The slower the burn rate the more timing advance is needed. If your carbs are too lean, the engine may well act like it needs more timing.

You could get away with a lot of initial timing, as long as you never load up the engine until you are at or above 2500 rpm. Remember when you open up the carbs the power valve richens up the mixture and it is going to burn faster. If you have enough timing to run good at light load (lean mixture) and step on it at low rpms you could ruin the engine. Vacuum advance fixes all this. Can your distributor accept a vacuum advance canister?