Magnum Swap Transmission Options

[ChrisRomello]

hello all!
I am considering doing a magnum swap in my 65 Valiant from my slant six and am wondering what I should do for a transmission. I plan on converting to a carburetor set-up to keep things simple. I am not looking to race the car; I just want it to be fun to drive. I know that I can make a 904 or a 727 work but are there other options that might be better? I would like to keep it automatic. Thanks!

 

[1963dartgt]

Watching this. I think you can use other transmissions but they require tunnel mods.

 

[GRANCUDA]

The magnum motor is balanced different than the standard LA small blocks. A magnum specific flywheel or torque converter must be used.

 

[TrailBeast]

hello all!
I am considering doing a magnum swap in my 65 Valiant from my slant six and am wondering what I should do for a transmission. I plan on converting to a carburetor set-up to keep things simple. I am not looking to race the car; I just want it to be fun to drive. I know that I can make a 904 or a 727 work but are there other options that might be better? I would like to keep it automatic. Thanks!

Depending on how the body differs from the Dart there are a few choices.
I am running an A500 (42RH Overdrive) out of a Dakota pickup in my Dart and it is real nice to have those gears.
It also bolts right up to Mopar small blocks, and as long as you use the Magnum flex plate the A500 goes right in with very minor tunnel mods (no cutting of the actual tunnel)
It's also possible to make the OD and lockup work completely automatic, meaning no having to flip switches.
Either purchase a shift controller for it (which I found kind of pricey) or it can be done with pressure switches like I did.

There is also a 2004R GM trans that they make an adapter to install, but the 200 would require some beefing up to last well behind a Magnum.

Then there's the 7004R GM which is the heavier version automatic overdrive.

The A518 (46RH) is the overdrive version of a 727 and almost definitely would require some floor cutting.

A modified trans cross member would be required for any of the above, as well as details like cooler lines, linkage setups and throttle pressure.

There's some food for thought and research for you to get started.

 

[Bobzilla]

Please clarify what you mean by "better." If you are going with a carb setup to keep things simple, then just stick with a 904 or 727 since it will be a simple bolt in deal. If you want an overdrive automatic you'll have to do some cutting and welding.

 

[TrailBeast]

Please clarify what you mean by "better." If you are going with a carb setup to keep things simple, then just stick with a 904 or 727 since it will be a simple bolt in deal. If you want an overdrive automatic you'll have to do some cutting and welding.

There is the whole Gear Vendors route, if keeping it simple is important and want the benefits of OD.
This is the only option I know of that does not require modding much but the speedo cable and driveline.
25+ mpg hiway with a 5.9 Magnum is kind of nice, and worth doing if the person is up to it.

 

[ChrisRomello]

• @TrailBeast thanks for the info! Overdrive does sound like a nice addition. I'll have to do some research on that.
• @Bobzilla As for "better" I simply mean shifting response and drive- ability.
• The 904 does sound like a great option for my build. From reading on here it seems that all I would have to do is swap to a V8 center link and maybe get a rear engine mount crossmember. Is this correct?

 

[Bobzilla]

If the car already has a 904 automatic and you put a small block 904 back in, the rear mount, crossmember, and driveshaft can usually remain the same, although I always suggest a good replacement driveshaft for any aggressive driving or racing. I saw a few factory driveshafts brake over the years in cars that were not crazy powerful, but always in cars that were beat on pretty hard.