Good points about the stop and the vacuum advance unit. However I remember a few years ago when I was looking at Lucas distributors for another project, I was surprised to find that the weights were all the same, the only variation in the mechanical advance curve being the springs. Maybe somebody like Distributor Doctor could confirm this, but I’ll check to see if I have any other evidence.Lotus-e-Clan wrote: ↑Fri Apr 14, 2023 18:43More to the advance curve than the springs. The working range is governed by a stop on the rotating cam spindle, the radial position of the stop determines max advance. Eg. If the stop occurs radially at 12 degrees then the max advance will be 24 degs plus the static setting. The springs also work against a matched set of weights. If the weights differ from those in the OE dizzy, then the advance curve will proceed differently.
Also lots of variation in vacuum capsule advance characteristics too.
Cheers, Richard