on a points type distributer how are you limiting the mech advance?
Mentioned numerous times in many old threads
The GM points and HEI work the same...it is the tail of the counter weight shape...
a 0.25 to 1mm rounded off the tail will increase the amount of degs in the curve.
Careful it is very easy to take too much off...
On the bar the rotor screws to, there is another hole, tap a thread, and using a grun screw, shape the head into a cam....this will limit the amount of degress and make adjustable...once the position is established, lock the postion with a spot of epo or locktite.
Caution, if u put to much in the weights can fall over the edge of the round fiber inserts they sit on....you can replace these by making a couple larger new ones and epoxy in place...
Both my points and HEI run 8Deg intial and total 32 ...24 in the dizzy.
This makes the load on the starter motor light, easy start....then with VA on manifold vac that comes full in at idle vac gives me 14 deg at idle once the engine has fired up.
(6 deg in the VA) gives me total of 38 degs at 3000 rpm....or 30 at cruise 60 mph. (approx 2400 rpms)
The VA drops right out about 1/3 to1/2 throttle about 10" vac...it is all in at approx 13.5"