1973 Cuda engine transmission swap.
 

Hello

I am a new member and have never posted to a forum of any kind so please excuse the newbie mistakes and feel free to correct me for any violations.

I have basic mechanical knowledge but have never owned or worked on a Mopar.

I have recently acquired a Basic, bone stock 318ci, 3speed manual Plymouth Cuda that will require an engine rebuild or swap as well as a transmission rebuild or swap. I have come across a 5.9L out of a 2001 Dodge 1500 with 110K miles for $700 dollars. It has a brand new 4bbl edelbrock intake and comes complete with all but a carb. He also has a 727 automatic trans as well.

I have 2 questions

Will the 5.9L bolt up to the stock 3 speed.

If I decide to go with the automatic ( car will be used strictly as a cruiser and I really don't want to do any shifting) will the 727 trans bolt up to the 5.9L and will I need to do anything special to make it work in the 73 Cuda.

I'm not trying to offend any Mopar purists by doing this but it isn't a numbers matching car and both the engine and transmission are not original.

Any help or advise would be appreciated.

The 5.9 oil pan doesn't fit the car and I'm not sure if the 318 pan fits the 5.9 but you will need a flex plate for a 5.9 and a converter but the 727 should work. Also if the 5.9 is early enough it will have both styles of motor mount boss's cast on it including the same as your 318. Also 5.9s have problems with heads cracking so beware of that.
personally I would go with a big block and four speed, that's my idea of a fun cruiser.

If you are going to go to the trouble of doing an engine & tranny swap, I have no idea why you would go with a later-era, non-Hemi Mopar V8. My '66 Charger has a 440RB/A833 transplant, and that is a very common on-the-cheap upgrade for late 60"s/early 70's Mopars. There are all kinds of resources and parts available for doing that swap. I gather that 392 Hemi swaps are fairly common as well, which makes sense because then you would be installing a "modern" Hemi. I will defer to the more experienced Mopar guys here, but my impression is that you will find far fewer aftermarket parts and services for retrofitting an earlier, non-Hemi Mopar engine. You might as well shop for non-Mopar engines.

I suspect you're being lured by the false economy of going with a cheap engine on hand. You can probably find a 440 RB for the same price or just a little more, and the potential re-sale value of a '73 'Cuda with a 440 transplant will be far higher. Plus the build-out potential of that block is much greater, if you get ambitious and want to seriously hot rod the engine. That mill has ungodly amounts of torque! From a dead stop I occasionally load in 3rd by accident (A833 has a tight throw and no shift gates, so it's easy to do) and the car doesn't stall, just lugs and grumbles. Check out the technical pages at 440Source.com for tons of info on rebuilding the "Poor man's Hemi."

And speaking of Hemis, if you dropped a 426 Hemi crate motor in your 'Cuda, you would probably get back the cost if you ever sold the car. Prices for original Hemi Mopars of that era are so insane that even a replica '73 Hemi 'Cuda would be fairly valuable.

I would also endorse Iowan's take on going with a manual transmission. Unless you are absolutely certain that you will only want to use the car for cruising and will never resell it, you are throwing away money and fun by going with an AT. I know some of the Mopar vets will disagree, because the 727 is used so much in racing, but you'll never get the full potential out of a big-block Mopar with a three-speed 727. Not for street use. I grant you, stop-and-go driving in my Charger gets a little old, working that big clutch, but it's worth it for the full control on downshifts. Besides, there is nothing more sad than a classic hot rod with an AT.

I just Google searched "Magnum 5.9L swap into E Body", came up with tons of info of people who have done this before, doesn't look too difficult.

Well, I understand that your resources are constrained, but I still think you are conflating two different goals into making a questionable refurbishment path:

--You want to get this classic sled rolling again for your FIL's sake. Well, presumably he knew how to drive the car with the original engine and transmission, so your $700 would probably be better spent getting the current drivetrain running again so that he can drive the car while he is still able.

--You would rather put your money towards restored drivability that will benefit you in the long run (an engine & tranny swap). I understand your thinking, but you would be sinking a big chunk of money into a drivetrain swap that may well turn out to be more difficult and take longer than you realize. There is nothing special about that particular later-year Mopar block AFAIK, other than that it is a Mopar. You might as well be swapping in a 351 Windsor.

I'm going to expand this to a broader statement about working with old hot rod sleds: once you start loosening the bolts on the motor mounts, you might as well tighten those bolts eventually on the most motor you can even vaguely afford. An engine swap is always a big project, so factoring in the cost of your own time I don't see why you would even take on the project without the goal of dropping in a big block. That is assuming that the car is not a numbers-matching collectible.

I would be curious as to what the more seasoned Mopar guys think, but as someone who has owned various flavors of 60's iron and know how other fans of those sleds think, I see--and have seen done--two different scenarios:

--Restore the car as close to a numbers-matching classic as you can achieve.
--Build out the car as a hot rod.

Otherwise, I don't see the point of touching the car at all. If it was a '73 Monaco, you'd be looking for a wrecking yard willing to tow away the car. But it is a classic muscle car model/year. At a minimum I would look for a 440 RB or Gen III 392 Hemi out of a wrecked car to swap in. A new 392 crate motor costs $8,000, and I'm sure you can get a used one a lot cheaper.