Making power out of the 318
the 3.21 gears are not there to stay i will be putting a new 8 3/4 rear end when this one shreds then i will re gear then but i am not putting any money into the rear end i have now
That's fine and makes sense, but don't change the fact that your stuck with them for a while, so you a cam for them (my choice) or cam for the future gears and live with it. And what are the future gears to be ?
Like a set of 3.55 helps but it's not really a huge difference from 3.21, it's a 3rd of a ratio difference ain't gonna all a sudden allow a super huge cam in a 318, future gears may still limit you more than you want.
Plus we got to talk tire size that's part of the ratio, so if future gears come with a taller tire you got to factor that in or otherwise you could end up with the same ratio.
Eg.. Divide 24 by the tire diameter to get it's effective ratio. So 26" = 0.92 and 29" = 0.83
3.21 x .92 = 2.95
3.55 x .83 = 2.95
So in that case you'd still have the same ratio
Here's some gear formulas
They don't factor in converter slippage
And gear could just be rear gear or the combination of the trans gear and rear depends what your looking for.
Gear x mph x 336 / tire diameter = rpm
Mph x 336 / rpm x tire = gear
Gear x 336 / rpm x tire = mph