73 Roadrunner - BB 4speed swap

[Hilljack68]

On a factory 318 3-speed manual floor shift Roadrunner, I'd be looking to throw in a 440 with a 4-speed. I know the K-frame is the same, but what about the shifter hole, and the tranny mount? Would this be a simple swap, with no fab required? Thanks.

 

[70chall440]

Assuming you use the right transmission the hole should be good, I "think" the mount is the same but I don't remember, if not they are readily available.

 

[Runcharger]

Shifter hole is the same, I believe the K-frame is different actually.

 

[YY1]

K frame is different between big block and small block.

DC used to offer conversion mounts and IIRC Schumacher did as well.
Kind of hard to tell them apart from standard BB mounts.

If you use "regular" BB mounts in a SB K frame, the engine may sit cocked and cause the trans to hit the floor pan IIRC on the passenger's side.

Shifter "holes" can be different based on bench/buckets and buddy seat or buckets with console/buckets with nothing.

Bench/buddy seat uses a short tunnel and a long shifter mount as well as different rods and a long shifter handle.

Buckets console/nothing uses a long tunnel and short shifter mount and a very short shifter handle.

 

[#41]

YY1 covered it all well. The only fab here is the motor mounts, and that depends on what you use for that. I have put RB and B engines into 73-74 318 cars a couple of times. It's a pretty easy swap. The only thing I would do different if I did it again is to cut and plate the small block K frame to make room for a wider variety of oil pans.

 

[YY1]

...and then there's the pass side spark plug access.

Factory BB cars had the lower portion of the inner fender removed and used a fiber/rubber curtain.

This may not be an issue with headers, but could be even more of an issue if you will be using factory manifolds not designed for a 73/74.