[r67cat]

Wayne, what I did to determine how much advance I was getting was to check the timing at idle ( no mechanical advance and vacuum disconected), note the rpm, attach my Mighty Vac to the canister apply vacuum, the idle will increase. Then reduce the rpm back to what I had originally and check the timing. Subtract the first reading from the second and you know exactly how much vacuum advance the canister can add at partial throttle. Rick