Tony, thanks for the compliments!
I've been out of the 6-cylinder tuning business for a while, especially the old stovebolt engines. Most of the engines I play with now are short-stroke, high-revving V-8's, and they take a little different type of modifications to perform well. The stovebolt engine's big advantage is low end torque. A little higher valve lift, without getting radical on cam duration is the way to go on a low-revving engine. Within reason, higher compression helps, too. We don't want to get into the premium-fuel range, especially with gas prices going through the roof, so about 9:1 compression is a practical limit for a street engine. It might require mid-grade gas, but that's only about a dime a gallon higher, at least in the mid-south area.
Here's a trick I've used in the past,and it seems to work well. If I restrict the centrifugal spark advance 5 or 6 degrees, and increase the initial spark timing by the same amount, low-end torque is helped, without getting the total advance too high. It's done by welding up the slot where the centrifugal weights travel and checking advance on a distributor tester, or with a delay-flash timing light. Someone mentioned a total advance figure of 34 degrees, which seems about right. Smallblock V-8's work best with about 37 degrees max advance, but they're maxing out at 7,000 RPM or a bit more. That's a full-power advance, with no vacuum added, I assume. Vacuum advance is a fuel-economy measure, and goes away when full throttle is used. It will add from 8 to 15 degrees of advance at light-throttle cruise, depending on engine design.
Too much advance is worse than not enough, IMHO. When my Dad was tuning the family dirt-track car 50 years ago (a flathead F*rd), he did some chassis dyno testing in a trucking company shop, one of our sponsors. The car was run at full throttle, and the timing was advanced until the max HP was reached, then the timing was advanced 1 degree more, and the power drop recorded. Back to max HP, and timing was reduced one degree at a time. It took 5 degrees of spark retard to get the same power loss as 1 degree too much timing! Food for thought!
Jerry
