total timing advance

[ed cougar]

Hi, I'm still messing with that dual diaphragm distribtor on my scj. Check this out, I can set my initial timing (vac. lines disconnected and plugged) to way up there around 18* then hook up manifold vacuume to retard (inner) port and the timing comes right back to about 12* at idle, thing is my total timing retains the high numbers say 42* and it all comes in around 3000 RPM. It really woke up this 428. Now I tried to lose the retard side of the advance but without it I have to run the initial to about 18* to get the 42 total so right now it seems to be my advantage to have it. The mechanical stop on the advance slot makes it impossible to achieve 42* unless I set initial to 18* whitch I think is too advanced off idle. thats where the retard comes in and pulls it back to 12*, there's nothing aftermarket on my engine and I'm trying to get the most out of whats there. Any opinions and expertise with distributors please reply for I feel that I may be missing something here, thanks.