Originally Posted By autoxcuda
275/60/15 rear tires that original poster has are pretty large diameter that cuts the effective gear ratio down.

Your overall ratio is about 50 rpm more than a bone stock 71 340 Duster with 3.23 gears and F-70-14 tires. They sold 1,000 of Dusters and Demons like that.

These are not new cars. They drove originally down the road at 3100 at 70 mph.

A F70/14 that originally came with 340 dusters is 26" diameter.

275/60/15 are 28" diameter.

This is a very handy quick visual tool to figure out rear end ratio changes: http://vexer.com/automotive-tools/speed-rpm-calculator

What is the exhaust system on the car? Full to the back, turn downs, Flowmasters even?


That speed calculator is really cool, I'll have to play around with that. But everything else you said I'm already aware of, it's just my personal preference to bring the RPM's down. I've seen guys pound their chest and brag about how they roll down the highway for 2 hours at 3900 RPM's, who the heck wants to do that lol.
I can pretty much drive the car anywhere right now, just want to make the drive more pleasurable, I'm installing my stereo today.

I run 3" pipes with turbo mufflers and turndowns right before the axles. I plan to install some tailpipes this winter to the back bumper.

1970 Challenger, all aluminum 528 Hemi, HDK suspension, Tremec 5 speed manual