I need a suggestion on what to get as far as a Muncie 4 speed. I am currently running a new crate 350 Delux with 330 hp. It is currently running a TH350 tranny behind it with a 9" rearend with 3:50 gears and posi. What is the best rout as far as a Muncie 4 speed. The close ratio or the wide ratio. The close ration consists of 2:20 first, 1.64 second, 1.28 third, 1:00 fourth. The wide ratio consists of 2.56 or 2:54, 1.91 second, 1.48 third, 1.00 fourth. I currently have in hand a close ratio muncie and dont know if that is the best rout for shifting and power. Please give me some advice. Oh ya this is all in a 1958 Biscayne.
Thanks

In that heavy of a car with only a 3:55 gear i would 100 percent run the M20 with the 2.52 first gear....A M21 with the 2.20 first gear will kill that car...

Stay away from the M20's with the 2.56 first gear. They are the first gen muncie and they only have a 7/8" counter gear pin..... Unlees they have the correct up grades they are really prone to breaking....


Keith

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Performance Engines
It's better to have a gun and not need it, then need a gun and not have it.

Can i replace that 1st gear with a lower one? What upgrades are needed to make the earlier Muncie stronger. I know that bearing retainer cap is smaller on those earlier ones. Found that out when I was getting a bellhousing. I needed one that housed a 11" clutch and 168 tooth flywheel. Those earlier ones only house 154 tooth flywheels and 10.5 inch clutchs. Had to get the "621" bellhousing. It has the larger bearing retainer/cap that is 4 and 11/16.

No you cannot change the first gear. The difference is between the input and the main drive ratio... M20's and M21 use the exact same 1st 2nd and 3rd gears......

The early 7/8" pin transmissions need to have the late model sincro rings with the step installed. This will require 1" wide slider hubs from a late model transmission or to machine the 1 1/8" wide orginal hubs down to 1" It will need a tight case for the cluster gear pin to fit into, or the case needs bored out and a steel bushing installed to get the proper fit back...The side cover will need the detent pin removed and a late model pin installed...And like you mentioned the late bearing retainer is a up grade also... All this work will help the transmission but as a whole it is still weaker then it's 1" cluster pin brother....


Keith

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K-Star Automotive
Performance Engines
It's better to have a gun and not need it, then need a gun and not have it.

So to check if there is the 7/8 pin compared to the 1" do you measure the input shaft diameter? Also if it is a wide ratio then it would have 2 cut rings in the splined area of the input shaft right? If close ratio then it would have no rings or 1 ring? So basically it is just easier to seel what you have and get the correct one or change the gears in your diff to lower gears. right? What gears are the best with the close ratio muncie? 3:73s or 4:10s? But would my posi unit be able to fit a lower ring gear like 3:73 or 4:10? I think there is a cutoff point where you would have to get a new locker housing.

If you are looking at the front of the transmission the cluster pin is under the input and to the right. It does not stick out of the transmission...

Factory markings on the muncie are M20's 2 rings...M21's 1 ring.... The problem is that over the years the aftermarket did not always follow this pattern.....

I personally would not change the rear gears... if this is a driver car and you stick a set of 3:73's or 4:11's it will becaome hateful running up the highway at 65mph......

Most muncie guys will let you trade that transmission in on the one you want ( thats what i do)... So you need to look for a M20 or have one built for you...IMO

Keith

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K-Star Automotive
Performance Engines
It's better to have a gun and not need it, then need a gun and not have it.

Hey Keith,,,, how about the 465 truck tranny? Wheel stand in first, then while trying to grab second you can take a sip of your favorite beverage, then finally onto third and fourth! LOL And its bullet proof!

L.O.L. yea i had a guy tell me one time he could speed shift one of those.... Some people???

Hey that Q-jet carb has the right first 3 digits on it,,, do you want it when i take it off????


Keith

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K-Star Automotive
Performance Engines
It's better to have a gun and not need it, then need a gun and not have it.

Sure, i'll take it. Let me know when. My wifes Caprice is now 20 years old this year and the qjet has NEVER been off or apart. Pretty good service from it and it still works fine. But it won't hurt to have a good spare built and ready to go on my next boring weekend!

Mark

I have a sm465 in my 78 chevy pickup 4x4. It's a great tranny for a truck. I really like it. It can be a bear to shift sometimes though. Definitely no powershifting, haha.