So I have a 66 Skylark GS with dual quads and a Switch pitch 400 3 speed transmission in it. It's been improved with things like porting, jetting, mild cam, etc. and runs consistent high 13's. 60 foot times around 1.92. I have it set to shift both times at 5,200 RPM's. It finishes the 1/4 mile at about 4,800 with the posi 3.55 12 bolt. total timing is 32 degrees with initial set at 12 degrees. I would like to improve the ET's without changing any more drivability. Hence I have been thinking about timing and RPM shift points. Opinions on OPTIMUM timing (total) for nailheads? Opinions on best shift points? Same for both shifts? Opinions on maximum SAFE RPM's? Engine has 150,000 miles, compression is steady at 190-200 in all cylinders, no smoke, no oil burning, heads, lifters, etc. all new! Rings all original.
