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Discussion Starter #1
What 4spd trans is a good fit for a '66 Chevy ll/SS? What Muncie is factory for this year? Differences of close and long simply the actual travel of the gear shift? M20 pros and cons, M21 pros and cons? A individual here on this site has a 4spd for sale out of his numbers matching Chevy ll/SS 2000mi since rebuild for $1600 OBO...
 

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First question is engine horsepower, that is what GM used to dictate Saginaw versus Muncie. I cannot remember what the line was, but it was around 300HP. There is nothing wrong with a period Saginaw if you are not running a high horse motor and / or driving it hard.

A thing to keep in mind, Saginaws and Muncies use different shifters, linkage and probably some random other little parts. It is not uncommon for people doing these conversions to end up with a miss match of parts, since "they're all the same...."
 

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I think that would rule out the Saginaw. Others will need to chime in if a stock Muncie will handle that. I know they made a few different versions and after a certain date (1969?) they were all heavy duty cases.
 
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Discussion Starter #5
Now, the M22 is a different animal, right? Fitment etc. Would love use the factory console.
 

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M22 a different animal. A factory 4-speed '66 likely came with a Muncie, but it could have been a Saginaw. Muncies seem more plentiful lately as many owners are going to overdrive automatics, 5-speed and 6 speed Tremec conversions. I see many more Muncies than Saginaw 4-speeds.

I'm looking for a Muncie as well. I'd like to find a '64-'66 M20 (wide ratio, with a 2.56 1st gear) for a Chevy II want to build. For a time, Autogear was selling Ultra wide ratio gear sets that would allow for a 2.98 1st gear and use the stock case, tail shaft and everything else. I've owned a few factory 4-speed Novas, and always wished that there was a wider gap between each of the gear steps. Heck, the engines are torquey enough and the cars light enough, and if I mated that to a 2.73 or 2.56 rear, I could actually cruise on the highway and get some better mileage. Don't compete at the Stoplight Nationals much anymore, so launch, wide gaps between 2nd and 3rd or 3rd and 4th are less an issue.

A first gear launch with 3.08 rear and 2.56 1st gear is a drive ratio from a stop of 7.88. With a 2.56 rear and a 2.98 first gear of the ultra wide-ratio gear set, you have a drive ratio from stop of 7.63, not all that far off. They payoff will be cruising at highway speeds and losing maybe 400-500 rpm.
 

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Now, the M22 is a different animal, right? Fitment etc. Would love use the factory console.
This is pretty feasible. Basically everything is available now if 100% correct is not the goal. It will look close to original.
 

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Dbs 66

I’m the member with the 4 speed for sale . The trans was rebuilt with I nodular gears and the owner had receipts when I bought the car. My car has a 480hp 383 and this trans worked great Draw back is 373 gears puts it at 3100 rpm at 65-70 mph so I threw in a tremec
This is a great tranny , shifted awesome and I only had it since rebuilt for a few months. Comes with rebuilt original linkage.

I will let it go to you for 1100.
with original linkage 1300.

M-20 with this internal set up can handle up to 475 , if your north of 500hp , I would not advise if you drive hard continually. My own opinion. People state all the time these are bullet proof , I personally disagree as clutch and pressure plate design has improved so much that a more direct load is placed on the trans more immediate than back in the day.
My two cents worth a penny 😎
 

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I have posted pics and casting numbers now on my posted wanted add for the trans , sorry for the confusion should have done that originally.
 

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Tires are important too. If you run a small street tire, you can have 700 Hp and you won't break the trans. But if it hooks and you throw a bunch of torque at it at low rpm, it's not hard to break a Muncie. I have a muncie in my current car, but if I was in your shoes, I would have a new one built for me. I like Aly Mcreal's idea and plan to run a 2.75 gear in my '63, with 400 Hp 350 and 1971 Muncie M20 with 2.56 1st gear and 26 spline input with Turbo 400 output. I'm tired of the 3.90 in the car now and the car is light enough that it should be quick enough and cruise on the e-way, and get decent mileage. That's my goal, anyway.
 

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Discussion Starter #12
I have posted pics and casting numbers now on my posted wanted add for the trans , sorry for the confusion should have done that originally.
I live in Goodyear, Az. I was actually looking at the map yesterday just to see where Clovis is...I have a awesome 700R4 in my '66, but ultimately would love to convert it to a 4spd. I have a 383 and about 450hp and a 12 bolt rear. I need to decide on this. Dan
 

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Dan ,
My suggestion is this . I do a lot of conversions and I will tell you , it’s almost the same cost to convert to a 5 speed as a 4 speed. I just finished another 2nd gen nova from Modern Driveline Conversions at it was right at 3400 installed.
let me give you a break down and it will help you decide:

3 pedal conversion
Bell housing clutch and pressure plate
Hydro clutch/ throw out/Ram clutch
TKO 600 2200 . 4 speed 1200-1600
drive line
Tunnel patch kit to raise floor
Cross member
Electric Speedo Conversion

so you would virtually be doing the same thing for a 4 speed or a 5 speed and as you can see , for 500 dollars more ( tranny cost difference ) you can have a tranny good for 550 HP and would last you for years. Tremec a trans are bullet proof , Maintenance free and oil for life install .

Would love to sell my 4 speed but your going to so close to a 5 speed cost with install I thought I should be transparent here.

Reach out for any help or questions , I have a great relationship with MDC company and they are amazing with walking you through anything you need or sending you install details and answering questions.
Hope this helps.
 

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Paddy . . . . when you break it down that way . . . . . you are correct , a good buy , thanks .

DB . . . . . I think like the 'old TV ad' - "pay me now - - or - - pay me more later" . . . . . . 'everything goes UP ,
and, you get even a "bigger & better deal" (other than cutting the floor tunnel ) . . . . . and, for me
............ I'm just a 'six motor car' (and, my Nova will remain a 'six' car (for me) .
Plus, for my 'Craigslist w/c T 5 = started out a $ 150.00 trans buy . . . . . in the end , after rebuild, 14 spline clutch , ( 2 each) ,
Jeep in-put shaft (which I didn't use, but still cost) . . . . . . . I DO have a very good tranny . . . . . . .
cost = about $ 2800 total , see what I mean .
Hey, I just talking , now . . . . . . and, for me - - I'm very happy . . . .

jim
 
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Discussion Starter #16
I hear ya. I have a sweet, stout freshly rebuilt 700R4 in the car now. Head bobs through each gear...unless I blow it up, I should be happy with what I have. Seems if you have a auto, you want a stick. You have a stick, you want a auto. :giggle:
 
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