Newb Motor Swap Question #1

[mknittle]

Both sm420 and 465 are slow shifting truck trans missions. When I was a kid we were taking them out and useing m21muncie and borg warner t10 car 4 speeds.
I am running a sm 420 in my jeep for the low first gear.

[arturo7]

After that post I did some googles as well. Bass ackwards I guess. I got motor specs and bellhousing numbers, but no belhousing specs....



I like the SM420 with that bellhousing, I don't think either would be hard to find. The big issue that remains to be solved is the clearance, specifically between the distributor and the firewall. I searched here and couple other places but didn't come up with any conclusive. Indications are that it will work, but I'd like to make sure before I start laying out cash.

[MrSinister]

the best way to figure dist clearance is to have the engine and trans mocked up, put it on a hoist and hang it in the engine bay and set it in the spot that gives you adequate clearance for the distributor and doesn't put you too close to the radiator. if you're keeping stock suspension and steering the other concerns are steering box interference with side mounts and the parking brake lever.

[arturo7]

Thanks, MrS. Unfortunately, I do not yet own a motor or tranny. I would like to have a better idea if it is going to work before doling out the lettuce.

[1project2many]

The big issue that remains to be solved is the clearance, specifically between the distributor and the firewall.

If you start with the factory bell on the factory crossmember then clearance won't be a challenge. The distance between distributor and firewall will be determined by the position of the front of the engine. If you build or buy mounts which replicate OEM spacing then you will have room for a traditional points distributor which could be converted to electronic ignition, or any one of several aftermarket performance distributors with a small cap. If you lower the front of the engine by 1/2 to 3/4 inch you'll have enough room for a large cap HEI distributor.

Get a truck bellhousing if you can find it. Car versions are different. Two of the bolt holes for the trans aren't threaded, there are two crossmember bolts in each side instead of one, and the angle at the bottom of the bell, where it rests on the mounts, is different as well. This thread talks about the differences and has some nice pictures as well: http://www.chevytalk.org/fusionbb/sh...hp?tid/222096/

[arturo7]

Thanks, 1p2m. And thanks again for suggesting the 4 speed w/ swapped rear gears. That makes so much sense I would have never thought of it.