4.3 Swap Help

trying to mate my 91 Chevy TBI 4.3 motor to a Muncie M22 Rock Crusher. The 4.3 came with the bigger 168 tooth flywheel which does not fit into my bell housing or clutch that came with the Muncie. I believe I need the 153 tooth flywheel but externally balanced. Any idea what vehicles may have had the flywheel set-up?

While I am posting I'd really like to see some additional 4.3 swap information. The Scott Milliner tread has been a fantastic resource. Are there any others out there? I see a lot of, "I did that swap" or "I'm thinking about ...." I am currently mocking up the driveline in the CJ so I need all the information I can get.

Thanks in advance for the help

DJ

 

From what research I've done the 4.3 came only with a 12 inch clutch and a large flywheel. That would require the larger Chevy truck bellhousing and a bearing retainer reducing ring (Novak or AA) to fit the bearing retainer on the Muncie. I bought a truck bell on e-bay. The part number is 460486 but there are others. I assume you already have the large bell so get the retainer reducer and use the larger clutch. I'm sure you can find a disc to match the input shaft size and spline count on the Muncie. You could probably fit a small flywheel but the balance would be off. I am in the parts collection stage so that's all the info I have.

 

Why do you want to run a close ratio car tranny??

Put in a SM 420 or 465.

 

ditto.....unless it will only see the road or you have 5.38 gears

 

I'd get the larger bellhousing and change the clutch. I know more money but path of least resistance. I know externally balanced 4.3's came with 10 1/2" and 11" clutches. I had a flywheel for one. But the flywheel is 168 tooth. You can get an aftermarket racing unit in 153 tooth but money. You might check out S-10 pu's and Blazers. They had smaller transmission tunnels and may have used the smaller flywheel. I know the 12" clutch won't fit in those bellhousings. Mine came from an Astro Van with manual transmission.


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You should be able to find a standard bell housing that will fit. The old bell housing I had before the SM465 swap fit. I didn't know there was different sized Chevy bell housings.

Have you run into the exhaust problem yet?
I have a source for a header set up that might work.

 

There are at least 4 different sizes that I'm aware of and that doesn't include location of the clutch release arm, mounts, bolt patterns, NV-4500 version, etc.
the Astro Van bellhousing I have in the garage has both standard GM pattern and butterfly style Ford transmission pattern with the indexing hole diameter of the small GM transmission front bearing retainer.



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I plan to eventually but for now I got the Muncie for very cheap and it already has an advance adapter kit to use the Dana 18. It will see a lot of city driving as I plan to use it as my main vehicle once complete. I found a guy in my town running a a SBC in an identical jeep with stock manifolds and steering. I'm heading over there tomorrow to take a look. Hoping to get a bunch of pictures, measurements and inspiration.

Thanks for all the responses. I'm going to call novak tomorrow for some additional input. I don't want to mock it all then need a different bellhousing. I didn't realize this would be an issue but that's just the nature of jeep projects.

 

Might enjoy it shifting like a car. 420s and 465s are huge and shift a bit slow.

 

The link to those headers. http://www.sandersonheaders.com/Sanderson-CV95-Header-Set-for-Chevy-V6-Engines.html
I saw a motor with these headers mounted to it and they look like they would work. They even sell a set that will clear the knock sensors in each head.