Hot Rods 1950 Desoto Flathead question...

I have a 1950 Desoto coupe S-14 with the original drivetrain. It has a flathead 6(250 I believe) and manual trans. My question , how hard and expensive is it to rebuild the flathead? Has anyone done this? I have a 383 big block Chrysler and 727 trans that I am going to put in the Desoto but I am thinging of keeping and rebuilding the flathead for a potential project down the road. Or should I just sell flathead and trans for what I can get and move along. I would appreciate and input.

 

You could do this...

 

WOW! That would be awesome.

 

There is a fair bit of hot-rodding you can do to/with the 6, and if you want to run a TF send a PM or check my web site...I can help you out.

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Your looking about $1500.00 -$1800 on parts and about $1300-$1700 on machine and assembly work. Depends on how wild you want.

 

Dare to be different, do some hop up features on the Desoto and it should woop the tar out of the 383 . My Chrysler 6 runs 14.50's in the 1/4 mile at 91 mph. First thing to do is a an old 37-38 3 speed tranny from a mopar. Plenty of them around and they are close ratio, and cheap. You will have to notch the bellhousing , but it works. Believe me, it works. We raced this combo for 10 years and still have it in the car. There are a lot of low buck mods you can do to that engine that I haven't seen mentioned on the innernet yet. The only store bought speed part that we had on our motor was the 3 -3 bolt to 2 bolt carb adaptors that we ran on the stock manifold. That car was retired in 1968 and we have been racing Hemi s/s cars since. Our next real project is all our Hemi knowledge wrapped up into a "BIG" inch Chrysler 6 with a 727 behind it. I haven't heard of anyone running a 727 behind a flathead Mopar , but I have an adaptor ! Should be fun.

 

Not hard to rebuild at all. Millions were made, they were made up to 1972 for cars, trucks, marine, farm machinery and stationary engines.

Most parts are available and not expensive. They are a very simple engine to rebuild. Vintage Power Wagons has all the parts too, power wagons used the same engine for years. They have NOS pistons for $75 a set.

I vote you keep the flathead in the car. If you want to hop it up, rebuild it first.

It is also possible to replace the Fluid Drive transmission with a T5 overdrive trans. Don Coatney did this, there is a complete photo series on how he did it on the net if you search for it.

 

Did you make your 727 Trans adaptor your self? I would like to know more about this kind of adaptor!

 

Great thread, got my MoPar blood pumpin'! Hey, this model isn't rodded often, so please do a build thread or post us now and then on progress, whatever you decide to do. (Oh, and I hope you keep Hernado's shining face on your hood! LOL)

 

Oh man would I love to do this to my DeSoto! I will be listening!!!

 

Incidentally 1950 DeSotos all came with Fluid Drive automatic trans as standard equipment, one of the first cars to do so. Don't let the clutch pedal fool you. Look underneath, the bellhousing is twice as long as usual to hold the fluid drive unit (looks like a torque converter) plus clutch.

 

IMHO, it is best to use the 904/A500.
The 727 has a much higher parasitic loss than the 904, and, as we all know, the 904 can handle some big power.

Pic of the 904 bolted to the six on my web site and some on ebay right now with free shipping.

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Wow. Awesome input guys. The reason I was going to use the 383BB is because I have it and know that it runs. Like most, I am on a budget so spending a couple thousand to rebuild the original flathead right now would be hard. My plan is to build a cool hot rod with old features, but still be dependable enough to take my family for a road trip.
THe car is complete, minus a couple small things like drivers door latch. It does have the fluid drive trans, which is cool, but the car has been sitting for a number of years. I am looking forward to building this cool car and I will definately do a build thread.
Here is a picture of when I moved it into the garage yesterday.

 

Have you tried to get the old flathead running? I suggest keeping it if you are on a budget, even if you got the 383 for free.

The reason is, these cars are murder to put a V8 into. 1950 was the last year of 6 cylinder only, for 1951 the chassis was redesigned to take the new Hemi V8 (Chrysler only, but Chrysler and DeSoto shared a chassis and body).

The front of the body is narrow and the steering is tight to the engine. To get the 383 to fit you will have to gut the car like a trout and replace front suspension, engine, trans, radiator, driveshaft and rear axle.

If you really want a V8 it would be so much easier to sell it and get a newer car. If you get a 58 or newer the 383 is practically a bolt in deal.

 

On second thoughts the 383 might squeeze in if you get rid of the steering box. I have a set of mounts to put a rack and pinion in there, plus a set of dropped spindle supports and some shock absorbers if you are interested.

 

Rusty, can the drop spindle supports be used for a disc brake conversion. I have seriously considered a frame swap or clip install so that the front and rear would be updated. Plus I have access to a s10 frame that could be modified to fit.
Also, I have not tried to get the motor running. As with most old cars like this, "it was running when it was parked". The brakes are shot and somebody pulled the distributer, which I have to install, but, who knows, it may run.
I really appreciate the suggestions guys.

 

If the disc brakes fit the stock spindle. The spindle support doesn't make any difference.

There is a trick for timing your motor you may not be aware of. There is a small pipe plug in the head above the last cylinder. If you take out the plug, you can drop a screwdriver or long wire down on top of the piston. This makes it a cinch to find top dead center as you slowly turn the engine over by hand. Time the engine to fire at TDC, this is not exactly correct but close enough to start and run. Make sure you time it when the first cylinder is on compression, you can tell when this is by the air wooshing out of the cylinder as the engine turns. With the plugs out of course.

 

They run well even when they sit
Rebuild the carb and tune it up

 

Yeah if the engine isn't a complete clunker I'd just run the flathead 6. Everyone that says you MUST machine them to rebuild them is over reacting. My dad has dozens of these engines and hes never gotten a single one machined. Just rebuild the carb and make sure your gas tank is clean and it should run fine. If it smokes drop the pan and pull the head off and just put some rings in it. The best thing about the mopar flathead 6 is they are beasts, you have to do alot to kill them, and if you take care of them they will last for years. You could also switch to a dual carb setup on your engine if it is the factory desoto engine. If I remember right it is a big block which was the same engine big Dodge trucks had in them and some of them 48-53 had dual carb setups from the factory

 

I'll disagree.....

There are so many v-8 swaps that it is near impossible to count them, and most are in the smaller Dodge/Plymouth cars. There is at least one guy with a B-RB swap on this board.
There is zero advantage to a frame swap (especially an s10).
Your front suspension is so far ahead of any other '50 model and many mid-50' design that even doing a front clip is questionable (other than perhaps the Jag).
The stock radiator has the capacity to cool a 383; replace it if it is damaged, not just to be spending money.
Obviously, the driveshaft will need fixin' if you do a swap and the rear axle should be changed even if you keep the flathead. The stock rear brakes are a PITA to rebuild and a disc swap up front will allow you to use disc in the back. Go directly to www.rusthope.com for a front disc kit.

If the steering box becomes an issue then use a R&P, but I'd drop the 383 in the hole to see exactly what is in the way first. There are dozens of exhaust manifold designs for the B-RB engines from 1958 to 1978, in cars and trucks.

Gret looking car!

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This is a strange question but I recently came across an old ford flathead v8. Any chance this could squeeze into my 50 Plymouth? Has anyone even done this before?

 

It would be a lot of work and kind of pointless. If you like flatheads, a 265 cu in Chrysler six will bolt in and do anything the Ford will. If you want to go to all that work to put in a v8 why not a better, later OHV?

 

Not likely been done before...really odd combo and would not be inexpensive.
If the Ford is in rebuildable condition it would help fund the install of a 318-360 which would be alot easier and produce 4x the power...

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I wasn't expecting to get this kind of response! This is awesome. I finally got the car to a place that I could work on it and took the front cap off. I will try to post pictures. I am also going to start a build thread soon.


I took one of the plugs out of the flathead and it did not look that bad. I did find that the 6 volt setup has deteriorated someand the coil was falling apart. With that being said, the engine looks intact and I may get to try and fire it this week. If it doesn't, big block it it is.


I may need to put this in another thread, but what is the general thoughts on a straight axle/gasser front. I have a thought in mind that this car would be cool as a gasser with the big block and maybe some fender headers...Any thoughts???Again, its just an idea, but not set in stone.

 

First thing you need to do is to post larger photos.

 

Sorry. I am an idiot when it comes to computers.

 

Mopar flathead sixes will run circles around Ford flatheads as far as cooling, torque and longevity go. All the Mopars in our family run straight 8s or 6s, stock OD (which came on all Desotos) and high speed rearends. We can cruise 80mph all day.


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Big block! I did the flathead thing there different but,... just dont put a smile on your face like 383 would...

 

Straight axle/gasser ?????????

Naw, ya really lost with that one. I am pretty sure it would be the only one and like the kid doing it to a Buick it will be a real odd-ball and I don't mean that in a nice way. Sorry.

If you feel the need to butcher a car then I would suggest using one of the 'popular' makes since you might actually find a buyer for it when the 'fun' factor is gone.

You have a car in pretty good condition to start with (I wouldn't mind own it) and the B engine swap I think would be a good choice. You can make a real sleeper with it and also make a terrific daily driver with a Jag IFS swap, but, if that is not the goal, then do what ever floats your boat.

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I'm liking this thread. Here's the flattie six that came with my '50 Special Deluxe. I don't know the history behind the engine (previous owner passed away) but it looks like it was rebuilt in the not so distant past. I'm looking for bolt on goodies to enhance it's performance as well (as my budget allows).



Dave