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I am building a 2wd work truck out of a '66 Chevy C20 Custom Camper. I have a 4bt from a bread van and had been planning on using an SM465 transmission for the time being while keeping my eyes open for a deal on an NV4500 to add later. Well, I just stumbled onto a deal on an early NV4500. It didn't come with a bellhousing, but after tons of searching and reading here I found several places where it was suggested that you can use an SM 465 bellhousing with an early NV4500 and just drill and tap the ears of the transmission to match the pattern of the bellhousing but, no one ever said that they had actually done this and there weren't any pictures posted either(at least that I found). I went to look at it with this in mind. I stuck the 465 bellhousing on the front of the transmission and can see absolutely no reason it wouldn't work. I may need to be careful with bolt length-especially if I try what I am about to suggest.

I've read a lot of discussion about the 10 degree lean and whether you should leave the engine leaning or lean the transmission etc. I would prefer to have my engine sitting upright in the engine bay if for no other reason than to avoid answering the question "why is it leaning?" every time someone looks under the hood. I am not crazy about leaning the transmission either, but would prefer that to a leaning engine and I don't believe that it would effect a manual transmission in any way. I am concerned about tunnel clearance though, but this may not be an issue at all.

On the four hour drive home from picking up the transmission I mentally installed it two dozen times. The thought occurred to me that since I am drilling the front of the transmission anyway, why not rotate the pattern 10 degrees in the opposing direction and then I could have a vertical engine and a vertical transmission too. I did a little bit of back-of-the-envelope math* and it looks like the holes would only move about 7/8ths of an inch from where they would be if I were drilling the pattern to mount the bellhousing square to the transmission.

It will likely be a while before I proceed with the drilling of the transmission. I have a ton of other things to do before I am to that point, but when I do I will document the process with pictures and post them here.

Am I overlooking some obvious pitfall? I can't think of any reason not to do it this way, assuming that my some of the holes don't fall too close to the edge of an ear. I am pretty certain any of the holes would anywhere near breaking through into the transmission case, but that wouldn't be a deal breaker as long as I am careful with bolt length and thread sealant and there's thick enough material there.

I'm stoked. With this transmission I can get by without changing my rear axle so in the long run it is going to be a lot less work going with the NV 4500 from the start.

*assumes an approximate 5" radius of mounting hole from center of bellhousing hole-it is probably a little longer than that: 5xTan10=.88
 

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You can do it, leaning or not, been discussed here before. Just mount the trans to the bellhousing, carefully mark the holes in the front of the trans. to match the bellhousing bolt pattern; I presume the retainer dia. and the bellhousing are both 5.125", drill and tap the holes in the front of the trans., NC threads are used for CI and Al, bottom holes should be blind to keep from getting a bath when the bolts are removed, besides, 4500 trans fluid is expensive. It would be much easier to do this when the trans case is MT, can use epoxy to make holes blind.
 

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update

I have finally gotten to the point where I can work on getting the bellhousing adapted to the transmission. To rotate the bellhousing 10 degrees relative to the transmission will require welding on material for the lower passenger side hole. I don't want to go that route, so I rotated the bellhousing back until all of the holes were in the best position. This only gives me 3 degrees of rotation, but that's what I am going with. My transmission will lean 7 degrees, but that's better than 10. Here's a picture showing that hole. The angle finder doesn't look like it is on 10 degrees, but that's just the camera angle.

DSCF5745.jpg
 

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Hey why are you rotating the trans 10 degrees?I have a chevy and am getting ready to drill a lakewood blow proof housing to match a nv4500.Have you done it yet?Thanks for any imput you might have.Oz
 

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The Cummins adapter that I have fits Chevy bellhousings and is designed to tilt the engine 10 degrees toward the passenger side in step vans to clear something (brake master cylinder??). I don't need to have mine tilted, and really don't want it tilted, so I am going to mount it vertically. If I re-drill my bellhousing to fit squarely on the transmission, my transmission will be tilted 10 degrees toward the drivers side. By rotating the bellhousing as much as possible before I re-drill it, I will minimize the tilt of the transmission. I have been working long hours and haven't had any time to work on it lately.
 

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Progress report

I had to take a hiatus on my truck for a remodeling project that is winding down. I have been able to work on my project a lot recently. Unfortunately there hasn't been much visible/photo worthy progress. While changing the crankshaft seals and taking care of the KDP I decided to pull off the oil pan. i'm glad I did. I found the support bracket for the pickup tube was broken. I've got all of that back together and have the transmission adapted to the SM465 bellhousing:





Rather than use bolts as others have, I opted to use 1/2" studs. Fine (1/2-20) on one end and coarse (1/2-13) on the other. I used a transfer punch to mark the center of the first one and, using a drill guide from an easy-out set, I carefully drilled it out in steps, careful not to break through into the case. I tapped the hole, finishing it with a bottom top, and used red locktight to keep the stud in place. With that stud as a guide i used the same technique for the other holes.

I have to run a new, larger air line from my barn to my shop so I can sandblast and paint the bellhousing. Then I can button up the clutch and transmission and start on motor mount fabrication.

It feels good to be back on track.
 

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More progress

I forgot to include a shot of tapping the holes. I was careful not to break out into the case and used a bottom tap to get the threads as deep as possible. With my bellhousing clamped in the desired position, I used a drill guide from an EZ-out kit to keep my pilot holes centered an square.

20140831_151137[1].jpg

Here's a shot of it buttoned up:

20141007_185926[1].jpg

I should have grabbed a shot from behind showing the transmission vs. engine relationship. Next time...
 

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So new to this thread and the 4bt built conversion. Hope I am not messing the flow of the thread. I am putting a 4bt in a 53 chevy AD on an S10 frame. I just picked up a 4bt yesterday and it has a 4 speed chevy trans on it. I want to put a 5 speed overdrive to work with my 3.73 explorer rear end. is the NV4500(or is there others that are strong and work) the trans I will be in the market for and will the 10 degree offset apply to this install??
 

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So new to this thread and the 4bt built conversion. Hope I am not messing the flow of the thread. I am putting a 4bt in a 53 chevy AD on an S10 frame. I just picked up a 4bt yesterday and it has a 4 speed chevy trans on it. I want to put a 5 speed overdrive to work with my 3.73 explorer rear end. is the NV4500(or is there others that are strong and work) the trans I will be in the market for and will the 10 degree offset apply to this install??
3.73s will be perfect (assuming a 29" tall tire) for cruising 60mph at the "sweet spot" rpm of 1,900.

Yep, the adapter will have the 10 degree lean. You could do like I did if you want to keep the transmission close to vertical or if you don't mind either the transmission or the engine leaning, use the stock NV4500 bellhousing that goes with the transmission. Honestly, if I hadn't stumbled onto the early NV4500 or a bargain like I did, and hadn't had that bellhousing on hand, I probably would have left the engine leaning to the right. It just worked out easier/cheaper to do it the way I did it and I got an upright engine out of the deal
 
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