The MSD pro distributor will need custom modification to get the curve right too.
You are wasting your money. You cannot cure this by simply throwing money at it.
Fix the HEI style distributor you got.
The appropriately placed 10 cent machine screw must not stick up so far as to interfeer with the motion of the advance weights.
The diameter of the head of the machine screw sets the mech travel limit by creating a positive stop as apposed to depening on the weights and centerpiece to establish the stop limit of the mech advance system.
This allows you to get the generous 24+/- ish idle timing and 34-36 max advance timing.
The springs adjust the rate of mech advance within these points.
Very light tension springs or springs of the wrong free length create unstable, inconsistant advance at idle.
Last edited by F-BIRD'88; 09-09-2012 at 02:01 PM.