69 427/390 4SPD Question

[Brad H.]

I have reviewed the AIM & the new Judging Manual and still have this question: My 69 427/390 has the 308 diff and 4spd transmission. The build sheet just says: 4 spd transmission. I know this is a stupid question, but would there have been a "typical" transmission used. Any help here is appreciated.
Brad

[Jim T.]

Re: 69 427/390 4SPD Question

I would guess with the information you have given that it is a M20 Muncie. Have you looked for the stamped transmission information stamped on the passenger side?

[Terry M.]

Re: 69 427/390 4SPD Question

There are Power Team charts in the NCRS Corvette Specifications Guide. In the 1968-1982 version 4th Edition, Spring 2011 the 1969 Power Team chart is on page 48 & 49. This chart will show what rear axle ratios are standard and which are optional and depends not only on engine horsepower rating, but transmission type and in some cases whether air conditioned (C60) or not.

3:08 with your engine is standard on 4-speed wide ratio and TH400 and air conditioning or non air conditioning does not change that. If that ratio was standard there would be no line notation on your "build sheet" for the axle ratio.

As far as I know we did not consider adding those power team charts to the most recent TIM&JG, but at 300+ pages it was probably just as well.

[John C.]

Re: 69 427/390 4SPD Question

Brad

If you have the build sheet and the option no. column is still readable it should list M20 or M21.

In 1968 the M20 transmission was listed as just -4-spd transmission- on the build sheet. The M21 was listed as -4-spd cl ratio tran- on the build sheet. I don't know if 1969 build sheets are the same, but I would assume so.

John

[Brad H.]

Re: 69 427/390 4SPD Question

Thanks Jim & Terry,
When it gets here, I'll get it jacked up and have more to go on
Thanks again,
brad

[Brad H.]

Re: 69 427/390 4SPD Question

Thanks John,
I assumed the build sheet would have the RPO numbers but it only says 4 speed transmission. It is a 69 model.