Thread: Give me some input for my wacky idea please.

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I’m not going to stay out of which engine to use, but I will give you an alternative for a transmission and transmission adaptor.

Use an A833 overdrive 4 speed transmission and build your own adaptor.

The A833 Overdrive 4 speeds were installed in Chrysler product cars and Dodge trucks and vans from the late 70s thru the 80s. The early ones used a cast iron case, while the later ones had an aluminium case (avoid the aluminium case ones as the cases tend to crack. The A833 OD is based on the regular A833 transmission (that saw duty in such things as the 440 6 pac and Hemi cars) and will definitely stand up to some abuse. They are not as sought after as a lot of other transmissions so the buy in is usually not that bad.

Building an adaptor for one of these is pretty simple. You need the thin 3/4" adaptor plate that was used between the Hemi and Poly engines in the late 50’s. Just cut the lower legs off. You will need a flywheel, either an early Hemi flywheel (8 bolt) or a 6 bolt Poly flywheel can be used. Turn the flywheel down to the diameter of the later SB Mopar flywheel and install a SB mopar130 tooth ring gear. You’ll need a small block Mopar bellhousing preferably with the large bearing retainer hole and you’re all set. It takes a standard Chrysler started (with a 1/8” spacer).

On the Hemi you do need to check and make sure it’s already drilled for a pilot bearing (cranks used in front automatic transmissions generally weren’t).

Now the fun part, you can run some reasonably deep gears and still get good mileage and low highway RPM.

I’m running a Tri-Power 354 Hemi in my 57 Plymouth with a cast iron A833 OD and 4.10 gears (the OD drops the effective ratio to 3.00). It gets 20 MPG at 75 MPH with the AC on and I’m not a bit afraid to hammer it.


I discussed some adaptors in some old Hemi posts I did several years ago that might help.

General Hemi Info part 3
Just some food for thought.

Originally Posted by Mike P

I’m not going to stay out of which engine to use, but I will give you an alternative for a transmission and transmission adaptor.

Use an A833 overdrive 4 speed transmission and build your own adaptor.

The A833 Overdrive 4 speeds were installed in Chrysler product cars and Dodge trucks and vans from the late 70s thru the 80s. The early ones used a cast iron case, while the later ones had an aluminium case (avoid the aluminium case ones as the cases tend to crack. The A833 OD is based on the regular A833 transmission (that saw duty in such things as the 440 6 pac and Hemi cars) and will definitely stand up to some abuse. They are not as sought after as a lot of other transmissions so the buy in is usually not that bad.

Building an adaptor for one of these is pretty simple. You need the thin 3/4" adaptor plate that was used between the Hemi and Poly engines in the late 50’s. Just cut the lower legs off. You will need a flywheel, either an early Hemi flywheel (8 bolt) or a 6 bolt Poly flywheel can be used. Turn the flywheel down to the diameter of the later SB Mopar flywheel and install a SB mopar130 tooth ring gear. You’ll need a small block Mopar bellhousing preferably with the large bearing retainer hole and you’re all set. It takes a standard Chrysler started (with a 1/8” spacer).

On the Hemi you do need to check and make sure it’s already drilled for a pilot bearing (cranks used in front automatic transmissions generally weren’t).

Now the fun part, you can run some reasonably deep gears and still get good mileage and low highway RPM.

I’m running a Tri-Power 354 Hemi in my 57 Plymouth with a cast iron A833 OD and 4.10 gears (the OD drops the effective ratio to 3.00). It gets 20 MPG at 75 MPH with the AC on and I’m not a bit afraid to hammer it.


I discussed some adaptors in some old Hemi posts I did several years ago that might help.

General Hemi Info part 3
Just some food for thought.

Mike, thanks for the info! That definitely helps out a lot! Let me ask you this about the Hemi. Right now it has 73,000 miles on it. I got it running and it runs good and doesn't smoke at all. Do I need to worry about the heads as in the valves and seats since we have no lead in gas these days? Will this thing have enough power with a holley and or a AFB or similar on a stock 4bl intake and cam? It's rated at 280hp but who knows it it still does that this many lears later. I was planning on an intake and cam swap, but I'm not sure if it wouldn't be more beneficial to just rebuild it. If I'm going to do that I don't know if I can swing it this year. LOL

In the early hot rod era, Hemi's were the engine to have in a 40. You are correct in that it is about 200 lbs heavier than the SBC you have in it. If you have a Mustang II setup in excellent condition, you can play with the springs and it will work. Be sure and check your welds and such on the Mustang II, many are made out of a light weight material and are cracking under normal usage. If you need to replace it, do so with a FatMan product. His front ends are made from a thicker gauge material than the others, yet his prices are very good. Now, a stock 354 with only a carb change, that will not run like the 350 you have in the car - more like a good running 283. Horsepower ratings back then were at the flywheel with no acc's attached and some were fudged a bit. To make the hemi a sweet motor, you will have to rebuild and do standard hot rodding mods. Resale value, much better with hemi, just a bit less with 350, less with Cummings. Transmission for hemi -good advice from Mike P, if you want cheaper, you can adapt an old torqueflight to it - could be bullet proof.
Good luck with your choices and be sure to post and let us all know. Ray

Originally Posted by Scooting

In the early hot rod era, Hemi's were the engine to have in a 40. You are correct in that it is about 200 lbs heavier than the SBC you have in it. If you have a Mustang II setup in excellent condition, you can play with the springs and it will work. Be sure and check your welds and such on the Mustang II, many are made out of a light weight material and are cracking under normal usage. If you need to replace it, do so with a FatMan product. His front ends are made from a thicker gauge material than the others, yet his prices are very good. Now, a stock 354 with only a carb change, that will not run like the 350 you have in the car - more like a good running 283. Horsepower ratings back then were at the flywheel with no acc's attached and some were fudged a bit. To make the hemi a sweet motor, you will have to rebuild and do standard hot rodding mods. Resale value, much better with hemi, just a bit less with 350, less with Cummings. Transmission for hemi -good advice from Mike P, if you want cheaper, you can adapt an old torqueflight to it - could be bullet proof.
Good luck with your choices and be sure to post and let us all know. Ray

Thanks for the input. I plan on replacing the stock MII cross member with a Fat Man cross member already. There's a list of things the car needs to make it right. I'd like to add a/c too since I have 2 little, little kids. So I don't know how far the money tree will reach out to this car. I have to watch it basically. LOL