The Stovebolt Site Forums The Parking Lot Big Bolts 1958 Chevy 4400(Thor) NV4500 Swap

I have been accumulating parts and pieces for this swap since I got Thor. I got a good start on it after we returned from Townsend. I had a few minutes to talk with John Lowery (John L) while at the SMN AD Show. He has an NV4500 in his Flatbed, albeit with a 350 V8. John's Truck uses an Advanced Adapter kit and bolts up nice. There is no such kit available for the 216/235/261 bellhousing configuration.

Some time back I had asked the question about mounting the NV4500 to a 235. Most answers were to change the main shaft to a longer piece for a Dodge Transmission and make a 1 inch thick adapter plate. There was one idea from EdPruss in Colorado that seemed straight forward. Mount the bellhousing directly to the Transmission case. Using the Muncie bolt pattern from the SM420 on the235 bellhousing and drill and tap the NV4500 case to accept it. Ed's idea was to drill into the Transmission case and run the mounting bolts from the inside to the bellhousing.

I happened to locate a Transmission from a '93 Chevy 3500 at a local wreaking yard, it was complete and cheap. I walked out on a 50% off sale day for $225.00

I acquired an additional bellhousing from HRL (Thank you Jerry :D) while in Townsend. The 235 bellhousing uses a 4-11/16" retainer hole, where as the the NV4500 has a 5.125" front retainer. I tried to work with my local Machine Shop to get the retainer hole resized, we just couldn't seem to come together one what needed to be done. In the end I used a die grinder to open up the retainer hole to 5.125" +.005". I used a piece of plate steel as a template and centered the retainer hole and then scribed the correct opening to be cut out. I finished off the hole with a 80 grit flap wheel. I think for a free hand job it came out nice.

After gutting the NV4500 Transmission (I am going to do a complete rebuild on it) I used the old front retainer to align the 235 bellhousing. Squared the Bell housing to the indexed the mounting holes. To my surprise the 235 holes actually fit just outside the case, there would be in need to drill into the case itself. The mounting holes at the top cleared just outside the case walls, the lower mounting holes were just inside the NV4500 mounting holes.

I drilled and taped the upper holes for 7/16 - 16 bolts. I test fit the bellhousing and everything lined up well. At this point I realized that if I were to use an Allen style bolt I could bolt the bellhousing to the case from the Transmission side and not need to fight with the upper bolts from the Clutch side.

All of this is a work in progress so please bare with me. I am trying to come up with a simple solution and make this a far easier swap. More to come.

I am anxious to see how this turns out as I may do the same one day with one of my GMC's.

Thor must be happy! Nice project!

This is definitely a work in progress. Once I get the Transmission ready, I'll pull "Thor" apart. Used him yesterday to move a rear axle I'm prepping for Chris (ndkid275).

I had a few minutes in the Shop this morning. I finished drilling and tapping the Bellhousing and Transm case. I stepped the bolt size up to a 1/2 x 16 NC.

With the top bolts coming thru the Transmission case and into Bellhousing I will need to have the Top Cover removed to install these bolts. I am not concerned about the weight on this connection point, as I Plan to use a rear mount Crossmember.

The bolt on the right side came thru in a perfect spot, is the left side the same?

John, Both bolts lined up inside the relief on the transmission case. I verified that I would still have access once the input shaft and gear cluster were installed. The left side bolt is actually a little higher up because of the Transmission case casting. I will post more pictures once I get everything cleaned up and start reassembly.