Although I'm probably not qualified to answer this, since I have never run 1/8th mile, my "guess" would be 4.56 or even lower...
Yes, it does depend on alot........but I know Valleyracer is aware of this. So I will add that with a basically bone stock motor, open headers, C4 and slicks(at 2850 pds). I ran a 4.56 gear. Shifted at 6,600 rpm and went through the traps at 6,300 rpm. Best was 7.71@84. With my current set-up, New, not so stock motor, headers, C4 slicks at 2,800 pds. and 4.86 gears, shift at 6,800 go through the traps at 6,800. Best is 6.55@105. Both was done on Footbrake, no transbrake here......old school! I would say looking at your set-up and times in the 1/4 mile. if you are trans braking, probably the 4.56, if you are footbraking probably the 4.86......again JMO.
Good Info Thanks for the good info , I am footbraking and was thinking in the 5.13 to 5.38 range ? New 306 will have 7000 RPM limit and H-beam rods , light weight pistons and lots of carb ! Any other suggestions ? Richard Miller
How about your tire size? I know guys running those gears but they have some pretty big meat under their car. I was doing those #'s with a 28x9
Still 28x9 slicks and C4 4200 stahl converter , sounds almost the same as yours? Do you hit 3rd gear just before the 1/8th mile? Richard
With the old 302 and 4.56's I was in 3rd for just a second....not very long, but I think your motor will rev. alot faster than my 302 did. How much does your car weigh and what gears are you running now in the 1/4?
The car wiegh's 3000 lbs with driver approx and 4.56 gear shifting at 6500 rpm going through the Quarter at 7000 rpm Richard
I was always told that whatever you shift at, thats where you want to be in top gear when you go through the traps. But going by your #'s a 5 something gear might work out fine for you. I did switch to the 4.86's(from the 4.56) when I had the old 302 in it and it only changed the big end rpm by about 400-550 rpm. The is a link that I got somewhere that has a calculator for picking rear gear selection, I will find it after my morning production meeting and post it for you.
