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Discussion Starter #1 (Edited)
Here are a couple of pics of the SM420 bellhousing mated up to the back of my 4bt. It looks like the starter pocket on the bellhousing is a lot smaller than the starter pocket on the 4BT GM Adapter. Will this be a problem? sorry both pics are rotated 90 deg. I'm concerned about the starter gear hitting the bell housing if it goes back any farther than the rear face of the flywheel.

Any suggestions. Is there a different bell housing I should use with the SM420?
 

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you should be ok with the starter gear. it will only poke out 1/2" past the ring gear teeth at most.
 

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Discussion Starter #3
1/2" will cause a problem. The front face of the bellhousing is much closer than that to the rear side of the flywheel. Would it hurt anything to cut a little out of the bellhousing?
 

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An easy way to find out if the starter will hit the bellhousing is to watch it while trying to start the engine.

To me it appears to be not quite the right bellhousing, as it needs to grow an inch or two for the bolt hole on the other side of the starter to line up.
If the starter will work with no problems that's great, but it still looks like the wrong bellhousing...?

Is there a better choice of bellhousings he should look for?

Grigg
 

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Discussion Starter #5
An easy way to find out if the starter will hit the bellhousing is to watch it while trying to start the engine.

To me it appears to be not quite the right bellhousing, as it needs to grow an inch or two for the bolt hole on the other side of the starter to line up.
If the starter will work with no problems that's great, but it still looks like the wrong bellhousing...?

Is there a better choice of bellhousings he should look for?

Grigg
I would do that but I don't want to screw up the starter gear. I'll pull the starter and measure the throw.

The bellhousing is for a small block chevy 350. Seemed to fit just fine for that application but not for the 4BT.
 

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I would do that but I don't want to screw up the starter gear. I'll pull the starter and measure the throw.

The bellhousing is for a small block Chevy 350. Seemed to fit just fine for that application but not for the 4BT.
If the gear looks like it will just rub a little if it does hit you won't hurt anything to try it for a second or two.
If it looks like a tooth on the starter gear could try to grab hold of the bell housing then I would be more cautious.

After you measure you probably want to give it a try and watch just to be sure.

Grigg
 

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That picture looks like the one you need, as it fits the Cummins, and the SM465, which also works with the older SM420 you have.
Have you figured out the mounts you will use yet?

Are you planning to drive this vehicle on the highway regularly? If so then you almost have to have an OD transmission, and may want to rethink your plans for the SM420?

Grigg
 

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Discussion Starter #9
Actually, if you look at the starter area, it looks like the fit is about the same as my bell housing. I think I'll try to stick with what I have and build a mount under the bellhousing, like most of the SM420 applications.

As far as use of the vehicle, it will be used primarily for offroad and local driving. I have thought about the gearing and driveability. To be honest, the stock configuration would not permit speeds above 55 or 60. I think will still be limited to about the same max speed. My main use over the past 6 years has been 90% offroad 10% max on road.

Here's what I'll have; 4BT in to an SM420 going to a divorce mount Landrover LT230, axles will be Landrover axles with 4.7:1 ratio, running 35" tires.
 
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