The Stovebolt Site Forums The Shop Area General Truck Talk What engines work w/ a SM420?

I have a '49 1 ton with a Muncie SM420. the engine is a 235 from '55. I was think of someday putting in a V8. What bell housings will the SM420 bolt to? can I use a small block chev with this trany?

Check this link:

http://www.novak-adapt.com/knowledge/sm420.htm

It's a Jeep site, but Jeeps use a lot of chevy stuff, including engines, transmissions and bellhousings

Yes, just about any V8 housing that fits a GM manual transmission will work. The SM420 will stand up to a V8 just fine, although you may find that you want an overdrive someday.

Frank,The sm420 bolts up to all the diff chevy bell housings even the full wrap alum car bells of the 60,s you would just have to drill out the threads in the bottom ears of your trans so the bolts can go into the threads of the bell.
But back to what I think you want to do....
To keep that trans in your 49 and go to a small block v8 ya gotta do 2 things.
1st you need a 55 and up 2nd series cast iron bellhouse from a gm truck with the chamfered pads that accept the rear motor mounts.
Get the mounts and hdwr also cause your,s are different,Which gets us to #2
Find ANY 54 to approx 72 1/2 to 1ton GM truck frame and salvage the trans crossmember out of it.
(these trucks might just have the bellhouse and mounts with it also)
The reason is GM changed the shape of the crossmember and style of the mounts.
Up to and including 53 the mount pads sat flat on top of the crossmember, under the bellhouse.
54 and newer the crossmember was "chamfered" at the mount locations to fit the new style matching bellhouse.
An ideal donor frame for you would be any 54 thru 55 1st series with std shift
Hope it wasn,t too confusing any ques. feel free to ask.
Regards Steve sr.