Thread: cruising rpms

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I just replaced my 4.56 gears down to 3.73's. I am now at around 3500rpms at 65 mph. I was just wondering if running that high of an rpm bad for crusing on the highway and if so whats a safe distance to go driving in those conditions. It seems a little high to me but its probly cuz of my th400?

thanx

That's still pretty high. How tall are the rear tires? I ran 3:90's in my '27, and with a 30 inch tall tire was cranking about 2500 at 65, if memory serves me correctly. (It's been 7 years)

The other factor is how much highway driving do you do? One guy in our car club was running 4:10's, and he couldn't go on many cruises with us because the r's were too high.

Don

I had the same problem when I had my Chevy I swapped to a 700R4,dropped from 3400 @70 to 2500 picked up about 4-5 MPG.Also the 3.08 1st gear in the 700 pulled it off the line quicker.

My 460 in my 89 truck turns about 3000 rpm at 65 and has 250000 miles on it.....C_6 trans and 4.11 gears.It was built when the speed limit was 55{it has the red number 55 on it} and at that speed the revs are about 2700 .