..finally tested the distributor.Initial was 15 and by 2000 there was about 22 degrees advance having full advance of 35 degrees around 3600 rpm. ( Initial plus mechanical )This is a very slow curve and would be very helpful if you're fighting detonation in a high compression sm block.Single stage springs are loaded initially and adding 1 weak spring should work great for
a street machine to bring advance in quicker.
no welding of slots etc.