[Garreett0]

What kind of speed / rpm differences will i notice with a 3.70 vs a 3.50 gear ratio. i have a 390 with a 3 speed manual.

 

[psivory]

There are alot of calculators online for just this comparison. One is here.
http://www.thedirtforum.com/rpmcalc.htm

Don't think you will see much of a difference going up that little. I recently went from 2.75 to 3.55. Still comfortable at 65-70 rpm wise with the new gears. (3 speed auto trans.)

 

[jerrym3]

I went from a 3:1 to a 3:50-1 on a 352/250hp 64 Galaxie (14" tires). Starts to tach up a bit at 65 plus.