427 Southern engine and ? igniton problem
 

I have a Southern 427 SO in my KMP 174, 6AL MSD box, 750 cfm Holley and Kirkham’s installed Holley electric fuel pump. I was using the distributor that Parham sent, but the car was suffering from suddenly dying at the stop light (even under very gentle deceleration) and dieseled unless the idle was decreased to where it was barely enough to keep the car alive. If you increased the idle, I think you were “in the primaries” and it would always diesel. After speaking with a couple of folks, I concluded the problem was the ignition timing (tho’ other theories were prevalent). Therefore, I wired the weights in the distributor and thus disabled the distributor's mechanical advance. Next I purchased a “timing computer” from MSD. It allows you to set the advance and the number of RPMS when it is all in.

With the unit correctly wired in, the car is very difficult to start unless the total advance is about 38° or so, and at 40° it sounds like it is exploding fuel in the sidepipes when you accelerate, and it diesels badly. The car seems worse than it was before the changes were made.

Another issue, and possibly related, is that the car (and this was before the MSD computer timer, which I’m sure is not a suspect for this problem) would spontaneously lose power on the freeway if the electric fuel pump was off. A quick glance at the fuel pressure gauge revealed that the pressure had fallen from about 6-6.5 to about 3. Indeed, kicking the electric pump back on from the dash switch rejuvenates the engine and it’s fine. Doesn’t occur with a light load (low RPM street cruising, or brief accelerations instead of a constant 4K RPM load). What’s going on here? It had been suggested that some of the issues here were related to “vapor lock”, but I’m not sure this issue is, as it happens even in 40° ambient temps. Not sure if the stalling and dying at the lights is related to vapor lock either.

Thanx for any help I can get.

steve