wide or close ratio

[jim cear]

Is it possible to determine which trans is in the car? I have a 327/340 with a 3:08 rear. Thanks

[Wayne M.]

Re: wide or close ratio

With that horsepower rating, I assume you are talking '62 thru '64 so it could be with a T-10 or Muncie M20.

The 3 to 4 shift is the key. Since the 3-4 gear ratio is 1.31 for the T-10 and almost the same 1.28 for the Muncie, drive at the exactly the same speed in both 3rd and 4th gears, note the RPM's in each, and if the ratio is according to the above for the respective transmission make, then you have a close ratio. Example 60 mph = 2460 RPM in 4th and 3150 in 3rd, then you have a close ratio. If 3rd gear @ 50mph gives 3640 RPM, then you have a wide ratio Muncie M20 with a 1.48 3-4 gap.

If the trans is on the bench, you can put lever in 1st gear and count input turns versus output (2.20 means close ratio).

[William C.]

Re: wide or close ratio

If the car is drivable, run it up to 2200 rpm in first gear and shift to fourth. If close ratio, it will run 1000 rpm in fourth, at the same speed if wide, about 850. It's more fun to double all the numbers and run it up to 4400 in low if you are adventurous, may also be slightly more accurate.

[David B.]

Re: wide or close ratio

For a 327/340, I assume it must be a 62 or 63? According to the "NCRS Pocket Guide Spec", the 3.08 was a posi option that was only available for both years with the close ratio (2.20:1 first gear)transmission for the 340HP engine.

[Duke W.]

Re: wide or close ratio

Only the CR was available with L-76, but to check what's in it now, attain 3000 revs is third gear and shift to fourth keeping speed constant. If revs drop to about 2300-2450 it's a CR; about 2000-2100 it's a WR.

The intergear ratios in both are the same except 3-4. The CR is close - about the same at 1-2 and 2-3, and the WR has a HUGE gap.

Duke