!!! THE ABOVE INFORMATION IS NOT CORRECT !!!I always thought the close ratio M-22 keeps your engine within its maximum power band (not letting the RPM's drop too far) between shifts maintaining maximum acceleration.
Here's a quote from a Corvette forum I just found...
The M-20 was a close ratio-- 2.20:1 low gear and less split between the gears until 4th @ 1:1.
The M-21 and M-22 were both a 2.54:1 low.
The M-22, AKA "Rockcrusher" had straighter cut gears and was the stronger of the Muncie gearboxes. Made more noise too.
I have heard the M-22 was also available as a 2.20 close ratio box, but given the intended use of those days, I tend to discount that as the close ratio was better suited to road race applications to keep the engine in the torque band.
Here is my post from the CRG regarding trans choices.
Not knowing your rear end ratio assuming a 3.73 or a 4.10...consider a M20.
A M20 has a steeper first 2.52 vs a 2.20, which with the 302 is extremely helpful in getting the motor spinning and thus making power.
If you have:
3.73's with a M21 or M22 the effective first ratio is 8.206
4.10's with M21 or M22 effective is 9.020
3.73's with a M20 effective ratio is 9.396 ~ steeper than a 21 with 4.10's... interesting isn't it?
4.10's with M20 effective ratio is 10.332 ~ IMHO this is the COMBO... it will LAUNCH the car in first... also makes it very very difficult to stall the car in first EVER.
Close ratio refers to the first gear ratio being closer to the direct through ratio of 1:1.
2.20:1 is closer to 1:1 than 2.52:1... isn't it?