67Dart273 said

I don't know what article you read but that is NOT what I read. The 480 they mentioned was the BEFORE and as it happens the mechanism was stamped 15* distributor (30 at the crank)

http://www.moparmusclemagazine.com/...opar_electronic_ignition_system/photo_13.html

A chart a few of us have found floating around: It is important to understand that this is DISTRBUTOR degrees which is 1/2 what you see at the CRANK

Modifying advance slots
degrees / slot size
6.............. .340
7................355
8................375
9................390
10...............405
11.5 ...........420
12...............435
13...............445
14...............460
15...............475
16...............490
17...............505
18...............520

Click to expand...

We wanted to run about 15 degrees of initial advance (at idle), and have the
engine timed for 35 degrees total (at full mechanical advance). That means the
distributor needs to provide 20 degrees of mechanical advance instead of the 30
in the factory plate. To shorten the mechanical advance, the slots need to be
shortened. The slots in our plate measured .480 inch long. We zapped the ends of
the slots with a MIG welder to get some of the advance out of our plate

Click to expand...