I just bought a frame off 67 Camaro with a new 350/351 HP and new 3 speed automatic.
It revs way to high at highway speed and want to change the rear ratio.
No tach so I don't know for sure what the RPMs are but can't drive it on the highway the way it is.
Any recommendations for a better combination. Not looking to race it just want to enjoy at highway speed with decent hole shot.

 

Welcome to the place,
Mark tire and mark driveshaft.
Lift rear wheels off ground and count driveshaft turns to one wheel turn.
Rough idea of ratio.
If, a 3.73 gear, engine rpm is half of mph - 60 MPH = 3000 RPM

 

thanks for the info.
any thoughts on what a good ratio would be to go to for more of a highway ratio?
3.08, 3.23?

 

Yes, 3.08

 

thanks

 

When doing the wheel spin and count method to determine gear ratio, how Everett described it is if you have a posi rearend (both wheels free wheel in the same direction). Because of how a differential splits the torque between two wheels, if you have an open diff, you need to hold one of the wheels from spinning backwards, or simply jack one wheel off the ground instead of both.
As far as what's the best ratio for you, the easy answer is.....that depends. If you're wanting off the line performance, with occasional highway driving, I would consider 3.55's. Maybe 3.23's if you spend half the driving time on the highway. Considering what you probably have now, I'm sure you'll be more than unhappy with the "performance" of a 3.08. I would find out what you have first, and go from there. If say you have 4.10's now, going to a high ratio like 3.08's is going to make the car perform like a dog by comparison. Gear ratios are about coming up with a compromise, you give up something on one end of the spectrum to get something on the other end.

 

Thanks

 

3.08 or 3.23 if you want a reasonable cruiser.

 

Make sure you get a quote on the work first and also get a quote on installing a modern 4 speed automatic with OD. I would guess the 4 speed automatic is going to cost 4X what the rear would cost but you not going to be giving anything up. If you do the 700R4 then the car is going be faster if you are playing around town and cruise better on the highway.

You can also search Gear Vendor for their add on OD.

I have a friend with a 1970 Grand Prix (the boat). He did a Cam and headers, 6 months later he did the FAST EFI upgrade and the next spring he had a 700R4 installed. He says of those upgrade the transmission upgrade was the most noticeable.

 

It also depends on what rear end you have. A 12 bolt would could have 3:73`s.3:31s 3:08. and it also depends on tire diameter as well.