I'm doing 3100 rpm's at 50 mph and 3700 rpm's at 60mph. Is this correct for 3.89 rear gears? Seems too high for freeway cruising. Any suggestions? Thanks
That sounds about right. That is also why most people are putting 5 Speeds now. I did when I had my GT350, and on a 67 I am building I will also do the same.
Mine might be off a tad, but I can double the first two digits of the rpm reading and that'll be close to my mph. ie, 3500 rpm ~ 70 mph
Sounds kind of high for 60 MPH. With 3.91 in my B9 in 4th gear I turn about 3000 rpm. Keep in mind tire size plays a role.
DJR, Exactly right re tire size. I'm running 215 or 225 60 series. I think I need a taller tire. Any suggestions?
That sounds more like 4.57 gears. Assuming the tire height is 25.5" 3100 RPM = 51.5 MPH 3700 RPM = 61.4 MPH For 3.89 gears, I get: 2600 RPM = 50.7 MPH 3100 RPM = 60.5 MPH 3600 RPM = 70.2 MPH I know I want a 5 speed. Need to put that aluminum T-10 in storage.