Mopar Sam said

Since I am cheap, here is how I do it. I drill out (you have to go easy, and have it clamped down good.) and tap one side of the advance plate for a 1/4" pipe plug. I put the plug in with loctite and grind it almost flush on both sides.
I then drill to size using this chart. Note, only do 1 side or it doesn't work right.

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...