have a small block v8 in my 69 camaro. has a 343 rear end. My RPM's are running around 4000 at 70 mph. What gear ratio is good for just crusing down the highway? appreciate any feed back.

thx

You've got very short tires on your car or 4.11's in the rear to be running that RPM at 70. With a 25" tire 3.40's would be about 3,300 rpm at 70.

A nice gear for highway cruising is 2.70's. This would drop your RPM to about 2,600 with a 25" tire.

I agree with Steve, the math just doesn't add up with your 4000 rpm @ 70 with 3.43 gears.

And yeah, a 2.70 or so gear would be a good "highway" gear, but it's really going to be a dog off the line with no getup and go at all. Overall, your 3.43 gear (if that's what it is) is really a hard gear to beat for all around street driving, both acceleration and cruising.

To accomodate lots of highway driving, I think most would tell you that an overdrive transmission, or a 5/6 speed manual is a better solution than swapping gearsets. Then you get the best of both worlds, acceleration and great cruise RPM's.

FWIW, I run a mild 350, 4-speed, 3.70 gear, 25.5" tire. Has enough acceleration to put you back in the seat, and I turn 3000 rpm at 62 MPH.

2.73's a dog ??? maybe if you're low on torque.

2.73's I would 2.0 60' all day and my best ET was 13.51 @ 101.7 only using 1st and 2nd in my 350TH. 80mph in first @ 6000rpm would surprise more than a few "ricers" :yes:

Is an overdrive trans in your budget?
Anything less is always a compromise.

have a small block v8 in my 69 camaro. has a 343 rear end. My RPM's are running around 4000 at 70 mph. What gear ratio is good for just crusing down the highway? appreciate any feed back.

thx

With 4000 at 70, you have 4.11's and short tires. 4.11's with stock tires gives about 3800 at 70, and 3.55's with stock tires gives about 3300 at 70. :thumbsup: