trying to figuare out if my gearing will be close (rpm) wise

Not sure if anyone can help or has some input

car made 649 Hp at 6400 rpm
weighs 2900lb with me

1.76 gear powerglide
28x10.5 slick

4.10 gears

i have a gut feeling i have to much gear , but not sure and want to address before going 2 hours away to track
I plan on running 10.00 and 10.50 index using the ez plate under the carb ( slowing car up )

10.50 index i feel will be around 130 plus/minus 5 mph
Any help would be greatly appreciated , not sure if there was an accurate calculator for this

1/4 mile

I think you should be able to run the 1/4 with the 4.10 gears. I had 4.30 gears in mine with 1.76 glide with 29.5 X 13.5 tires crossed the 1/4 around 6700 mine with me in it is 2940

The auto math handbook has a lot more writing on this topic than I could ever share in a post here but, The formula for overall gear ratio for automatic trans is (tire dia/335) X (rpm/mph) standard trans replace the 335 with 340. I highly recommend that book for any gearhead. Using this formula you have to know what your target trap rpm would be.


mph=cubed sq.route of (hp/weight) x 234

Should be close with the 4.10 ! The 4.10 gear you will probably have to turn it about 6700 to 6800 rpm through the traps. 3.80 or 3.90 gear would work great should be around 6500 rpm through the trap . If your going to spray it 3.70 or 3.50 gear. 1/4 mile . Just my opinion based on my setup

whitefield wrote:Should be close with the 4.10 ! The 4.10 gear you will probably have to turn it about 6700 to 6800 rpm through the traps. 3.80 or 3.90 gear would work great should be around 6500 rpm through the trap . If your going to spray it 3.70 or 3.50 gear. 1/4 mile . Just my opinion based on my setup

i can live with 6700-6800 rpm


i will have to just try it and see