If you use manifold vac, do you still set the initial timing to 9-12degress btc? How does it dial it back under full throttle? Doesn't is just stop advancing?
Yes, when you open the throttle the vacuum advance goes away and you only have mechanical advance. The timing you really care about is the timing at full throttle which has all the mechanical advance and essentially no vacuum advance. If you optimize that, the timing for idle and partial throttle cruising will be fine with the vacuum advance working
