So after talking to this "knowledgeable" mopar guy I hope you now know why we questioned whether or not your dad knew how to setup the distributor when he built the engine.
For reference, here's a chart with slot lengths. You have to multiply the distributor degrees x2 to get mechanical advance.
Quote:
dist. degrees X 2 + initial= total
dist. 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
So if you wanted 20* of mechanical advance you'd need about a .400 slot. Add 15 initial to that and you get 35 total.
Also, when you start revving up the engine, what rpm is your total advance all in by? Total advance and the rate at which it comes in are both things you dial in when you setup a distributor.
