Gear ratio ??????????

[Morris R.]

Can anyone figure out what ratio i have in my 66 corvette 327/350hp l79? Going 70 miles per hr and reading 3000 rpm's. Thank you

[Michael J.]

Re: Gear ratio ??????????

I would venture a guess of 3.55, sounds about like my '67 with a 3.55.

[William C.]

Re: Gear ratio ??????????

'65 Corvette sales manual has a wonderful little chart in it regarding Speed@ rpm for various rear axle ratios, yours would be 3.36

[Michael J.]

Re: Gear ratio ??????????

Here's a calculator I use:

http://www.angelfire.com/fl/procrastination/rear.html

[Jim D.]

Re: Gear ratio ??????????

If you have rear tires that are the same diameter as the originals, you have 3.55 rear end gears.

[Mike F.]

Re: Gear ratio ??????????

You can always jack up the car, put a mark or piece of tape on the rear wheel, a corresponding mark on the drive shaft, spin the wheel (by hand) one revolution and count how many revolutions the drive shaft makes.
3 1/3 turns = 3.36
3 1/2 turns = 3.55
3 3/4 turns = 3.70

[Joe R.]

Re: Gear ratio ??????????

Morris,

Here's some more info for you:

https://www.forums.ncrs.org/showthre...eferrerid=2667

https://www.forums.ncrs.org/showthre...eferrerid=2667

Joe

[William C.]

Re: Gear ratio ??????????

Might also check the code on the rear axle, 3.36 -AM, 3.55-AN, 3.70-AO, if Posi, AK for 3.36 open rear 327 only. 3.36 was the most common in smallblocks by far in '66.