‘67 GS; Muncie swap

jjpetts

Newbie
Hey good morning everybody. My name is Jared and I’m a brand new member leaving my very first post here on the forum. I’ve been reading past threads for the last two days and am already looking forward to everyone’s input.

I am currently deployed overseas, and planning to be back in the next 1-2 months. I’ve puchased a ‘67 Buick GS, site unseen from a great guy up in New Jersey. I’ve been looking for the right GS for about three years, and have finally brought one home (Kind of. It’s set to be delivered to my place next Saturday).

The reason for this post:
This was an original 400ci // 4 speed car. Over the years someone has dropped in a 455ci // TH400 combo. My first order of business is to swap out that auto, and get a gearbox back in this ol’ girl. I’ve settled on a Muncie with Gearvendors OD unit. Now I want to make sure I get the right Muncie for the job. And try to save some money where feasible. I talked to Jeff at Midwest Muncie, who I liked very much and he will sell me everything for the conversion, brand new, for $4700. $2400 of that will be the M22z. The rest is conversion parts. I also talked to River city Muncie who gave me a very similar quote on the gearbox. I liked both guys and thought they both seemed extremely knowledgeable.
Still thought, if I buy everything brand new, this conversion comes out to about $8k after the tranny, gearvendors, conversion parts, and driveshaft. I can swing it, but would really rather cut that number down if able.

The car still has a clutch pedal installed and has a 10 bolt with 3.36’s. I intend to keep the 455ci for awhile, and add a gearvendors behind the Muncie.

-Anyone have thoughts on how the M22z will behave in this car?

-Will I wish I’d gone with a different Muncie, or different gear set?

-I’ve not done this job before; Can anyone give me a complete list of the conversion parts that I’ll need so that I can shop around and see if there’s a cheaper way to piece this together?

This is my first classic Buick and I’m looking forward to everyone’s thoughts and inputs.
Thanks in advance guys,

-Jared
 
Jared, In your shoes, I would just do a trans that already had OD like a Richmond 5 speed or T-65 6 speed. Then something on the order of 3.55 gears would be in order.
 
If an overdrive is desired, I agree with Dr, Frankenbuick.

Here are a few things to consider before dumping 8+ grand into your drive train:
- I drive a '67 GS 400 with an original M21 and 3.36 gears and am happy with it. I drive it on trips up to 500 miles. For the first half hour it seems like it is reving a bit high (pretty close to 3 grand at 70mph), but you will soon become accustomed to it and it is fine. Heck, in the day some people drove 4.11s at highway speeds!
-Something many people don't think about is engine design to work with overdrive transmissions. An overdrive sounds great, but then they want a "lumpy cam" which is not a good combination.
-An M21 is more than enough transmission for the car unless you may be going for tubs and super wide tires.
-With a combination of M22 and super traction, you will also probably want a rear end upgrade from the original BOP.
-If you were to simply through an M21 in it for starters (most economical) and try it, it would also be a viable option to up the rear gears a notch for more highway driving if you found yourself on the highway enough to warrant it, There will be no payback on mileage to any overdrive conversions for the number of miles any of these cars get driven.
 
Thanks a lot for the input guys. My post was getting long and didn’t want to ramble, but here is some additional info.

I really respect the pros of just throwing in a Tremec 5 or 6 speed. But part of the enjoyment from owning and driving these things (for me) is the experience and nostalgia. I prefer the idea of a period correct Muncie with some gear whine.
I doubt it will see any track time, and I plan to keep pretty mild street tires on it. Probably 9” BF T/A’s or equivalent.

Trying to upload some pics of the car in case anyone cares, but it’s telling me the file is to large. Not sure how to amend that.

Thanks again for the input and wisdom guys. Keep it coming.
 
The pictures on your phone may be 24 inches wide on a computer, if it doesn't offer you the opportunity to upload a smaller file size, try opening it in some program and changing it's "physical size" by half. If the site doesn't allow the upload currently, it is big! Hope that works for you. Otherwise, you could upload them to https://www.teambuick.com/upload/, and I will edit them for you and send them to you for publishing.
 
Awesome input! Thanks everyone.

Can anyone speak from experience on these two fitment questions:

-What’s a realistic expectectation for the amount of tunnel surgery that I will have to do to fit the O/D unit?

-The 455 engine has a set of long tube headers installed. Should I expect the factory style clutch fork, linkages etc to have fitment issues?
 
Unless yours were custom made, the headers are either/or when it comes to auto and manuals . But, that doesn't mean there won't be fitment issues. The manufacturers made them to fit as many years and applications as possible. This means moving or denting a tube now and again to make them work with a manual. They are generally not bashful in telling you this once you have purchased them. You will have evaluate how well your linkage lines up with the headers once you have it and decide if what is needed, if anything, to proceed. Come on now, a hydraulic clutch would not be in line with the authenticity of the 67 Buick manual transmission "experience and nostalgia."
 
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