67 coupe rear end

[bdgiesen]

I have a 67 6cyl  3 speed saginaw car that I am putting a 350 with a 4 speed muncie. My quesion is how do I tell what rear end I have. With the 6 cyl it seemed to wrap pretty high at 65 mph. Also what would anyone recomend for a rear end gear for a good hiway car.
thanks Brad

[KurtS]

Look here: http://www.camaros.org/drivetrain.shtml#RearAxleNumbers

[bdgiesen]

OK I checked the codes and I am running 3.08 gears. That figures to about 3670 RPM at 70 MPH. That seems to high for a 3000 lb car. Any suggestions?
Brad

[tom]

Try what you have for starters, then consider taller tires, a wide ratio tranny, then look into changing gears. The "economy" set that was optional was 2.56

Tom

[KurtS]

I'm not sure where you went wrong, but with about a 26" tire, you should be at 2800 rpm at 70.

[rich69rs]

I was about to make the same observation, but Kurt beat me to it.

For the Following:
                Differential Gear = 3.08 to 1
                Transmission Gear = 1.00 to 1
                Tire Diameter (Inches) = 26.00
                Vechicle MPH = 70

The computed engine rpm would be:  2787


By comparison, if you changed to a 2.56:1 rear end, everything else remains the same, computed rngine rpm would be:  2317

One other possibility is that you really don't have 3.08 gears.  Axle stamp may indicate 3.08 gears originally, but they could well have been changed.  May need to take of the cover and look at the OD of the ring gear which should be stamped with the ratio or count the ring and pinion teeth and calculate the ratio.