Very Early Chevy To T90 Adapter

I purchased my 56 CJ5 with a Chevy 283 conversion already done. From what I have been able to gather, the conversion was done in the early 60s. I pulled the engine, trans, and transfer case out with the idea that I would be able to stop some of the leaks - everything but the engine is original to the 56.

Since I had everything out, I decided to freshen things up a bit. In the process, I came across a clean Even Fire 3.8L Buick V6 that I decided would better suit my needs. This is where things started heading south. A bellhousing from Ebay, steel flywheel, clutch, and pressure plate from Advanced Adapters (just down the road from me) and I thought I was set.

The bellhousing has dual bolt patterns but my research indicates that it is compatible with this conversion. The GM bolt pattern aligns with the bellhousing (even though the pictures makes it look like it is clocked to the right). Now finally to my question - should the adapter plate have the transmission bolt pattern clocked to the right? Pictures of new adapters look like the T90 bolt pattern aligns with the GM bolt pattern. Mine is clocked a few degrees to the right.

Pics are too large to upload - I will have to reduce the size and post later.

 

Ok I figured out how to get the pics small enough.

 

just a thought perhaps its clocked that way for driveshaft clearance? dropping the right side a little will increase driveshaft to starter clearance by lowering the front output on the transfer case.

 

That would make sense. Reading other posts about engine placement, the general consensus seems to be that you move the engine about an inch to the left for drive shaft clearance. This one was moved a little over an inch to the right - see modification to the cross member in the pic. It has the new style steering so I am not sure why they did this.

 

I can see in your picture of the adapter the distance of the bolt heads to the top edge is different from side to side, clocking the trans in relation to the engine. Was this also the case with the 283 and that bellhousing?
It does look like the clocking was engineered into the adapter plate, and you may be correct that it was for additional driveshaft clearance.
I have a T90/BW to GM pattern adapter in the garage, and I will check it out tomorrow to see if it "clocks" a couple degrees.
-Donny

 

Looks like it is in the chevy bell housing . I have a BOP bell . and it clocks the transmission down on right .I didn't use it cause the other starter bump was too close to master cylinder . maybe this is another reason they moved engine to right . stock buick bell doesn't do this

 

The bellhousing is an optical illusion. Because it has two different bolt patterns it appears that the adapter plate it rotated a couple of degrees to the right. If I remove the bellhousing and set it on a flat surface upside down (top two bolt holes on the table) the top two transmission mounting holes are sitting parallel to the table.

I do have another Buick bellhousing from the late 60s that only has the single starter bump. I chose this one because it has better center alignment. Never even thought about master cylinder clearance - might need to rethink this. The Chevy bellhousing that came out only has a single started bump so that wouldn't explain locating everything to the right.

 

Unfortunately, I wasn't planning on an engine swap when I pulled everything out so I didn't take a lot of pictures. These two show the original Chevy bellhousing while still in the Jeep.

 

Do you have a pic of the back of the bellhousing without the adapter/transmission case attached? it looks from the pic to me a combination of adapter and bellhousing bolt pattern clocking. That BOP bellhousing is not a stock Jeep V-6 bellhousing and there were plenty of GM cars that clocked the transmission down on the passenger side. Looks to me like this is what you have.

 

I don't have any pics of it on the engine but do have these from before it was cleaned up. The casting number puts it at about 1965.

 

Have you come too far down this path to turn back? The 283 is a great little small block V8.

 

Just for reference the back of the bellhousing is always the transmission side. The bellhousing in the picture is what is rotating the transmission clockwise (down on the passenger side). Look at the outline where the adapter bolted up. Plainly visible.

 

Unfortunately, I am past the point of no return - I sold the 283. Since the original conversion was done a long time ago, a lot of things weren't done right. Distributor clearance was done with a hammer and still rubbed against the firewall - couldn't adjust the timing let alone change points, cap, etc. Exhaust hit the frame. Motor mounts were cheesey, engine smoked, etc. I figured that since I would have to make a bunch of modifications and a minor overhaul anyway, I may as well drop in something a little easier to work on.

I also wasn't terribly happy with all of the weight in the front end. Not that it gets off road as much as I would like, but with Pismo Beach just a couple miles down the road, most play time is spent in the sand dunes. With the Buick, aluminum intake, aluminum bellhousing, lose the original generator - I dropped over 120 pounds. Now when I add my winch, I will be back to about where I started.

 

I really is an optical illusion. When I get a chance I will pull the bellhousing back off and take some pics with a tape measure. Sitting on a table upside down (top two ears touching the table) the top transmission mounting holes are parallel to the table.

 

I guess to address your original question, if everything lines up when it's bolted in, I don't see why having it clocked a few degrees would hurt anything. Maybe one of the guys who has done more swaps will chime in. If it's true that it could add a little clearance for the front driveshaft, you should be in great shape.

 

Yep. No doubt better bottom end torque than the proposed replacement. Seems to me all it would need to meet modern expectations is one of the many EFI systems that will bolt on it.

 

Ok - finally got back into the shop. I had to pull the adapter and bell housing back off to check the center bore alignment. While it is off, I can show that the bellhousing is not clocked to the right but rather an optical illusion. Turning it upside down and measuring the distance from the table to the bolt holes shows that they are parallel to the top tabs on the bellhousing.

 

My concern is that the original fabrication work doesn't seem to have accounted for the clocking. The rear cross member doesn't seem to be dropped on the right side. The rubber mount on the transfer case is seriously collapsed while the transmission mount appears to be pulling apart on the left side. It looks to me like they just used the rubber mounts to make up for the rotation.

I guess I will have to wait until I am ready to drop it back in to see what kind of clearance issues I have. The whole point of the post was just to see if it is normal for these adapters to rotate the transmission. I appreciate all of the feedback - this has certainly been a learning experience.