47 desoto custom v8 318 swap?

[Guest 47desotocustomv8]

Hi, i have a 1947 Desoto Custom Fulid Drive. I live in Marathon Fl and not very many shop work on these cars down here. I drive alot all around Florida and would LOVE to make my Desoto a reliable hwy driver. The Fluid Drive tranny dose not want to work any more but the ORGINAL motor runs great but needs a new carb.

I aslo have a carb. 318 motor and auto tranny, i want to swap the both into my Desoto. The 318 is a stock motor not raced out at all im not trying to make it a "race car". I have a few questions first thoe, thank you for you time and help.

#1 Has any one done something like this what are some problems im going to run in to?

#2 Is there a place or shop i can order the motor mounts from?

#3 Is there an auto tranny that will bolt onto my orginal inline 6 motor

#4 Is there a non oil cooled carb that will fit and work for the orginal inline 6

I would preffer to keep inline 6 in the car if i could fix thoes two problems "tranny and carb" i love the car and would like to keep most as orginal as possable.

#5 Is there anything i can do to the inline 6 to get a little more power out it? "she cant keep up at hwy speeds" or even get close to it:D.... Me and my 16 mounth old son Todd Jr. will be doing most of the work our selfs. Sons/ kids are the best most and valuable parts of our lives.

THANK YOU ALL VERY MUCH FOR YOUR TIME AND HELP,

Todd Frank ididit_84@yahoo.com

Edited March 6, 2011 by 47desotocustomv8
spelling (see edit history)

[JACK M]

You will run into steering clearance problems as I think the box is on the inside of the frame.

You will have to make your mounts and probably a crossmember, And have a driveline made.

If you want a parking brake you will have to change the rear end.

[Rusty_OToole]

It would be a lot easier to fix the original engine or trans. If you do a search for "fluid drive" in the Chrysler and Dodge boards you will find lots of info. There were a couple of very long threads about 2 years ago that will tell you all about them.

Engine and trans are both very strong reliable units. Most of the trouble with the trans comes because it is low on oil, or the wiring for the electrical control system is messed up. Both these things are easy to fix if you know how.

Have you done a compression test? How is your oil pressure? If it is in top shape your car should be able to keep up with traffic up to 60 or 65 MPH with no trouble, and have a top speed close to 90. If compression is above 100 on all cylinders you probably need a tuneup. If compression is down you probably need a ring and valve job. If oil pressure is down too, it is time for a complete rebuild. Normal engine life means a ring and valve job around 30000 to 50000 miles, rebuild around 80000 to 100000.

No other carb will work other than the original. It contains 2 switches that control the transmission shifting. Best to get it rebuilt by a real expert like the Carb King who specialses in old time carburetors.

To try to change to another engine, would be a nightmare. It could be done but would be a lot harder than fixing the original engine and trans. Don't forget, your hand brake is on the back of the trans so if you try to swap in a 318 you will have to replace engine, trans and rear axle. A good hot rod shop should be able to do this for $5000 or $10000 but if they are not real experienced, are more likely to abandon the job half way through and leave you with a butchered non running car. And when you get done, you will have paid out a lot of money to destroy whatever collector value or originality the car had, in other words will be worth less money than when you started.

There are other nightmares to it, like also having to change the electric system to 12 volts so the motor will run. Then what happens to your 6V negative ground wipers, radio and heater?

My recommendation, find an old gray haired or bald headed mechanic who understands the old cars. Or sell it and buy a newer car such as a 1955 or newer Chev that already has V8, automatic, 12 volts etc. It will be a lot easier and cheaper than trying to hack a DeSoto into something it was never meant to be.

Edited March 6, 2011 by Rusty_OToole (see edit history)

[Rusty_OToole]

Here is a link to a wiring diagram for the transmission. M6 transmission all the same Dodge, DeSoto or Chrysler 1946-53

M6 Semi auto wiring diagrahm for reference - www.P15-D24.com

Note, that the solenoid interrupter switch and governor, are all in a row on the right side of the transmission. This is not clear in the illustration.

The same web site has a wealth of info on old flathead MoPars.

Here is another page that will give you some insite into what a flathead DeSoto is capable of. Note where he says "at high altitudes, at speeds above 70 the motor smooths out like a turbine". This in a 3 ton, eight passenger limo with 4:11 gears. Towing a trailer.

1951 DeSoto Suburban cars - long term report / car review with trailer towing

You might also note where he says, after rebuilding the engine with a couple of improvements, its performance took away all desire to change to a V8.

Edited March 6, 2011 by Rusty_OToole (see edit history)

[Rusty_OToole]

Given the number of retirees in Florida I am amazed there are no old time mechanics. Are there any antique car clubs or cruise nights in your area where you can meet other old car fans and find out where they take their cars?

[Guest 47desotocustomv8]

Thank you very much for the info. There are not many car meets / clubs in the fl Keys ive been asking around but no luck let. Im not new to cars and mech. i paint and do body work for a living one of my orther cars is a FAST 383 supercharged iroc z that i built my self "with help from max" ,has not gone to a dino yet but she flys. I think im leaning towards fixing motor and tranny where can i get ahold of "carb. king". im going to do comp. test tomarrow and check on the oil press. Is there a auto tranny that will bolt to the inline 6? "not 3 on tree"

Edited March 7, 2011 by 47desotocustomv8
spelling (see edit history)

[Rusty_OToole]

Suggest you get hold of a repair manual and fix the fluid drive trans. They are pretty rugged, 9 times out of 10 there is nothing wrong but the wiring messed up and possibly need to top up the oil.

Carb King is a carburetor expert who posts here sometimes. I have not done business with him but he seems to know what he is talking about. Here is his web site.

THE CARBURETOR SHOP

It might be possible to change the trans but not worth the effort. Frankly if the trans scares you that much it would be easier and cheaper to sell the car and buy a newer one. The 47 DeSoto is a surprisingly good road car IF everything is in good shape, just as it is. If you really insist on V8 engine, auto trans, 12 volt electrics, etc etc just buy a newer car. Even a 1957 model will have all those things right off the bat, at no extra charge.

If you have any specific questions about the carburetor post them in the "Technical" section and he will see them.

[Guest 47desotocustomv8]

Thats is a huge help. I dont think the word for the tranny change is "scared" thoe dont get me wrong my supercharged camero is a five speed, i was just trying to make it a little more driver friendly. With all the help from all of you im going to keep it as orignal as possable . again THANK YOU