Bill – happy to share my limited information from my slightly over stock mid-1960s injected Ford 300 six cylinder with 3.90 gears. Compression ratio close to 11:1, cam not radical at .512 lift and int. 260 exh. 274 gross duration with lobe separation at 110 using 1.6 rocker ratio. This engine has run at 3 different tracks in a 1450lb front engine dragster. At Bradenton, my friend used it to secure his nhra competition license running 9.40-9.50s. At Speedworld before they closed, it ran 10.00-10.10s and at Bandimere it runs 10.70-10.80s. I looked up the 3 tracks and Bradenton is 19 feet, Speedworld was 1470’, and Bandimere is 5800’. At our June Bandimere race, temperature was 95 degrees, humidity was 17 percent and the DA was 10,200’.
At Bandimere I’ve run with both straight methanol and with 22 percent. Straight methanol it runs 11.00-11.10. With 22 percent it runs 3/10s quicker. Timing was 34 degrees for both straight methanol and 22 percent. Main jet with straight methanol was 110 and with 22 percent it ran best with a 95 main jet.
Did install a high speed lean out but have not used, just bracket racing for fun. The first thing you will notice with nitro is more engine torque off the line and after a pass, the cylinder head/combustion chamber runs much hotter over straight methanol. Your decision to switch to 4.56 rear gear is a good one. With more and more nitro, resulting in more torque, you will continue moving to lower gear ratios (4.10, 3.90, 3.55, etc.) numerically.
With your 2 step launch and only 15 percent nitro, probably okay. I’m guessing once you move closer to 50 percent nitro and above, could be issues. After your run, and seeing your plugs, you will know right away if 10 percent richer tune was good decision. Alan
p.s. Agree too FIE website nitro notes excellent.