Engine for daily driver 46 desoto

[Guest carcaliguy]

Any suggestions on what to do for an engine on a 1946 Desoto S11? I have a 1946 Desoto 2dr that I want to make a daily driver. It has the original 6 with fluid drive but I don't want to have issues going up and down a mountain pass 5 days a week. I want to go 75 mph most of the drive. I was told that the original engine is OK but think that I should go with a sb mopar. I have a few 318's and a great running 273 with trans and rear. But the temptation to get an ls1 is always there.

Any one have a Chrysler flat 6 that can travel 75 MPH or did you do a V8 swap?

Thanks.

[Guest CarAdMan]

Carcaliguy - In 1972 I replaced the worn out engine in my '41 DeSoto businessman's coupe with a Chevy 6 and a powerglide. Blair's Speed Shop in Pasadena made the mounts and machined the driveshaft. It was a smooth running machine, even at 75mph. Of course at the shows I always got the comment, " Why didn't you put in a slant 6 ?" - RICK

[Guest De Soto Frank]

Hoo-boy.

The ruling opinion here will be "keep it stock and keep your speeds under 60 MPH".

For the last 14 years or so, I've owned a 1941 De Soto that I've maintained as a driver / tour car.

It has the same basic engine as your '46 ( 236 cid), except with slightly smaller bore ( mine is a 228 cid). The stroke is the same. It is happiest under 60 MPH.

Most MoPar sixes with Fluid Drive have 3.54 or 3.73 rears. They sound pretty "busy" at 60 MPH, although if in good repair, they should be capable of maintaining 60-65 MPH for prolonged travel.

Mine is happier at 55-60 MPH.

Suggest you hit the following websites and see what info you find:

Desotoland DeSotoland: It's DeSoto Utopia - DeSoto Cars and Service ( look-up a fellow by the name of Jon Robinson - he has a '50 De Soto that has been his daily driver for many years, and he used to live out in CA, and dealt with a lot of mountain driving )

P15-D24 Homepage - primarily a Plymouth and Dodge website, but all varieties of Flathead MoPar are welcome, and some of the guys there get into performance upgrades, T-5 tranny conversions, etc.

If it were my car, I would leave the drivetrain alone and find roads that would let you drive 50-60 MPH. Pre-1955 MoPars were built for a different era and highway system than the mid'60's muscle MoPars listed in your signature... think of your De Soto as a time machine that can take you back to a more relaxed, saner era... why flog it to death trying to drive 75 MPH all the time ?

If I want to "go fast", I leave the De Soto at home and take my '60 Chrysler Windsor, with the 305 HP RB-383, 2.93 rear, and Flite-sweep tailfins !

[Rusty_OToole]

Don't be a sucker. Sell that DeSoto and buy a newer car. Get one that already has 12 volt electrics, V8 engine, power steering, power brakes, and whatever else you want in a car.

There was an unbelievable amount of progress between 1947 and 1957 in all lines but especially Chrysler.

Much easier to just start with a more modern car. I recommend a 55 56 or 57 Chev, every part is available and every problem has been solved, it is by far the best, easiest and cheapest car that will do what you want. You can probably buy one with all the modern improvements for no more than a new Toyota Corolla. Far easier and cheaper than trying to turn your DeSoto into a modern car.

[60FlatTop]

Some might say to just put on a set of radial tires.

Bernie

[HarryJ]

The engine isn't the issue at those speeds it's the suspension, steering, and brakes. You can get cars of the 20's that will cruise at speeds arround 70 mph. You don't want to be trying to maneuver at speed on today's expressway with a car of that vintage!

[Guest carcaliguy]

Thanks for the reply,

I want to get a 1960 Desoto but they are hard to find. In my search I found the 46 s11. I decided that it is more cost effective to drive an old car, paid off, runs good, cheap to fix, and worth something than drive a new car. The only cost I have is gas. I do all my own work so I don't mind dropping in a late model engine. I do not want to sub-frame the car. 55-65 just wont cut it in the socal area. The 99 vett is a great car good fuel 23-28mpg, and easy 75+ speeds. I just don't like plastic. I want a great looking car and this 46 would be a great way to start my day, and my drive to work.

I have been to Blair's, how much for the setup?

I don't want a 55-57 Chevy, nice cars but I would just sell, I have a 1955 olds 98 that Just drove for the first time today, need to redo the brakes. Power seats/windows/brakes.

I like the straight 6 Chevy idea, I also found people setting the complete car on an s10 frame. I would like to get this thing on the road this winter.

Here are some pics when I got her:

https://picasaweb.google.com/carcaliguy/1946DesotoS11?authuser=0&feat=directlink

Maybe I can buy an old benz diesel, and drop that thing in her....lol.

[Guest De Soto Frank]

Well.... it's your car.

I've been driving flat-head MoPars since my college days ( 25 years ago), and did plenty of interstate travelling between home & college in a '48 New Yorker... put over 40,000 miles on it during college days....

I have put nearly 30,000 on my '41 De Soto in the last 10-15 years.

I have yet to find a need to modify one from stock.

Why not get it working as a stocker and try it out ? You might be surprised.

Jay Leno keeps the majority of his antiques stock, and he lives in SoCal, I believe...

[Pontiac59]

Swap out the rearend for a later model Ford or Dodge with the same wheel lug pattern and a more highway friendly gear ratio and that will help immensely, although the car will be something of a dog at stoplights. With the leaf spring rearend in that car it's relatively simple to do without altering the car at all, so it could always be put back stock.

A more extensive change would be to convert to an overdrive transmission like a T5 - I believe you can get an adapter to hook one of these to the Chrysler six now - which will do the same thing.

There also is the possibility of digging up a factory Mopar overdrive trans from the '40s or early '50s and installing that. This will require the least modifications, but will be hard to find and probably need to be rebuilt when you do find it.

All of those things will reduce engine RPM at highway speeds, which will allow the car to be happy with 70-75 MPH if done correctly.

[Bleach]

Whatever engine you drop in will sound busy because of the rear end. Unless you add an over drive or change the rear end with friendlier gears you won't gain much.

[Guest De Soto Frank]

Swap out the rearend for a later model Ford or Dodge with the same wheel lug pattern and a more highway friendly gear ratio and that will help immensely, although the car will be something of a dog at stoplights. With the leaf spring rearend in that car it's relatively simple to do without altering the car at all, so it could always be put back stock.

A more extensive change would be to convert to an overdrive transmission like a T5 - I believe you can get an adapter to hook one of these to the Chrysler six now - which will do the same thing.

There also is the possibility of digging up a factory Mopar overdrive trans from the '40s or early '50s and installing that. This will require the least modifications, but will be hard to find and probably need to be rebuilt when you do find it.

All of those things will reduce engine RPM at highway speeds, which will allow the car to be happy with 70-75 MPH if done correctly.

Trying to retrofit trannies / OD's is a can of worms on a MoPar with Fluid Drive.

If someone is really going to go down this path, I strongly suggest getting on the p15-d24.com site, as many other guys have done a lot of legwork and experimentation and have learned some hard lessons... they are willing to share their hard-earned wisdom !

(And just as an FYI - there are no MoPar overdrives between 1941 and '48 model years... Chrysler Corp dropped the option in favor of pushing their new Semi-automatic tranmissions. The OD option returned in 1949 on certain models. The rear-end swap is probably the cleanest, easiest way to boost top cruising speed. With the M-5 semi-auto that was stock in the De Soto S-11, top gear( 4th ) is direct drive.

Again, the guys at p15-d24 have found out which other rears fit and what mods are required.)

I still advocate living with the stock De Soto and seeking out more friendly roads.

[Guest carcaliguy]

Yea I know that the rear is an issue, besides with the e brake setup on the Desoto it has to go. I think I found a way to bolt in most of my 67 coronet parts. I have a 4 door car that runs great, a parts car for a 67 charger. Thanks for all the help, I will be looking into this alot more, I just don't want to have a car that has limits because of speed, brakes, etc.

[Rusty_OToole]

55 Olds = perfect. Fix it up as your driver and keep the DeSoto for weekends.

I just can't understand gutting the DeSoto and turning it into something it isn't. If you want to drive an S10, drive an S10 and save yourself a lot of work. Or, just stick a DeSoto emblem on the hood.

How about this for an idea. Find one of those "geniuses" who put the S10 frame under his old car and buy it. There are lots of them for sale cheap, "just needs a little work to complete". Once in a long while you even find one that runs, those ones are cheap too because no one wants them compared to a stocker. So once again a chance to save some time and money.

I see you have a couple of mid sixties Satellites. They would make the perfect daily driver either slant 6 or 318. Do your maintenance by the book and 200,000 reliable miles is in the bag. And a way better car than any crappy Chev pickup frame with high heels and lipstick.

Or if you are really serious about hacking the DeSoto look up Don Coatney's car. He drives a 48 Plymouth sedan all over the country at 70 MPH but he has, ah, modified it a little.

It has a hopped up flathead six connected to a 5 speed manual trans and a Dakota rear axle. The rest of the chassis is basically stock, I think it still has all drum brakes and like I say, he drives it all over the place with no problems.

[NTX5467]

Back in the middle 1970s, a friend was looking for a "reliable car" that was cheap to purchase, so he/we found a '50 Plymouth sedan in the back yard of the original owner. He purchased it and had it towed to his house. We got it running pretty easily! Even the electric choke still worked!

In talking to the service manager at the local Chrysler dealer (who used to ride Indian motorcycles in his earlier days AND remembered Dodge Bros cars!), I asked what other engines might fit in the car. He replied that the early HEMI V-8s would, which also means that the later LA 318/340/360s will too, as they have the same bellhousing bolt pattern. Which also means the A-block TorqueFlites, too. He said they were a "bolt-in" situation. If the prior A-block TorqueFlites will fit, then so will the later TorqueFlite OD transmissions, I suspect (although they might need a little re-shaping to clear the tail shaft housing, plus a "made" driveshaft).

In later years, there are replacement driveshafts which have "normal" u-joints rather than the ones the cars back then came with.

As for the drum parking brake on the trans output shaft, they were used into about 1964 as a normal situation on full-size Chrysler products, as I recall.

In other words, there should be no problem keeping your DeSoto ALL MOPAR and also having a vehicle which will run how you want it to.

Another variation would be to put the early HEMI in it. That stuff's still available, too, in repro!

Check out Street Rodder magazine to see what's out there as to chassis options. Disc brake upgrades. Electric power steering assit kits. Different steering columns. BUT you'll probably want to change to 12V to get many of these later model street rod items to work.

The comments about brakes and suspensions are vaild, but I also suspect that if you can get them rebuilt with new rubber items and a set of good HD shocks, PLUS adding a larger sway bar on the front and maybe one on the rear, you might be surprised at how good it might be. Then, some upgraded brake linings and dual-circuit hydraulics to round it out.

NO NEED to follow many down the path of "small block Chevy" in upgrading an old MoPar vehicle!!!

Regards,

NTX5467

[Guest carcaliguy]

Yea I just want to take the easiest route to get her on the road. I will not sub the car or modify it to the point that I cannot go back to stock. I have an extra Chrysler 6 also. I just know that I wont be happy with a 75 top end speed and will redo the thing if I get it all running and trucks pass me in the slow lane. I'm not even going to paint her at first, just do the seats and make the driveline as tight as possible. I used to be one of those mopar or no car, still am, but there is a reason that Chevy is popular. This is no performance car, its a daily driver. While I can go all stock and drive it local, that in my opinion sucks. Cars are built to be driven. Driven far and for several years. A stock Desoto will sit covered up while this car is going to be seen just as much as your Toyota pickup. I like your input NTX5467, I do want to keep it mopar, just thought I would see what other are doing, a buddy of mine puts 5.3 motors from 2005 and up Tahoe's in everything, cheap, good power and 200k + on miles all day. not bad for a 500-1000 dollar setup.

[Rusty_OToole]

Yea I just want to take the easiest route to get her on the road. I will not sub the car or modify it to the point that I cannot go back to stock. I have an extra Chrysler 6 also. I just know that I wont be happy with a 75 top end speed and will redo the thing if I get it all running and trucks pass me in the slow lane. I'm not even going to paint her at first, just do the seats and make the driveline as tight as possible. I used to be one of those mopar or no car, still am, but there is a reason that Chevy is popular. This is no performance car, its a daily driver. While I can go all stock and drive it local, that in my opinion sucks. Cars are built to be driven. Driven far and for several years. A stock Desoto will sit covered up while this car is going to be seen just as much as your Toyota pickup. I like your input NTX5467, I do want to keep it mopar, just thought I would see what other are doing, a buddy of mine puts 5.3 motors from 2005 and up Tahoe's in everything, cheap, good power and 200k + on miles all day. not bad for a 500-1000 dollar setup.

What is the matter with you? You already know the answer to your question, it is built into this post.

You want the EASIEST route to a daily driver, you KNOW the DeSoto is not it, so why don't you go with a car that will do what you want?

YOU ALREADY HAVE at least 3 cars that are way better than the DeSoto, why blow all that time and money trying to turn a DeSoto into something it is not? Are you mad at your body, have too much time and money to burn or what?

[Guest De Soto Frank]

Just a comment on Don Coatney's P-15 Plymouth ( he's one of the regulars at p15-d24.com) ... I think Don eventually put a "big-block" Chrysler / De Soto six in his Plymouth, but in any event, he was working with a car that did NOT have Fluid Drive, which made his project a lot more simple.

The Fluid Drive equipped MoPars (Dodge, De Soto, Chrysler) have a different bell housing, and the rear cross-member/rear motor mounts sit further back than on a "dry-clutch" MoPar.

Other than the 5-speed T-5 tranny from a Chevy S-10, I'm not if Don's made any other mods to his car... it's been a while since I've checked-on with him.

Nice guy though, and willing to discuss his project, trials, tribulations.

[Rusty_OToole]

"In talking to the service manager at the local Chrysler dealer (who used to ride Indian motorcycles in his earlier days AND remembered Dodge Bros cars!), I asked what other engines might fit in the car. He replied that the early HEMI V-8s would, which also means that the later LA 318/340/360s will too, as they have the same bellhousing bolt pattern. Which also means the A-block TorqueFlites, too. He said they were a "bolt-in" situation."

This is wrong. Before they made the first V8 models their cars were made to take inline engines only. A V8 will not fit without hitting the steering.

A V8 can be forced to fit but you have to do a few clever tricks, like using the correct early A body exhaust manifold that wraps around the steering box and offsetting the engine to the right. They are far from a bolt in.

By the way I used to own an Indian motorcycle also a Vincent, and several Harley Davidson, Norton, BSA, Triumph etc. and I not only remember Dodge Brothers cars I have a flathead DeSoto in the garage.

Edited October 4, 2011 by Rusty_OToole (see edit history)

[NTX5467]

His comment about the early Hemi was his, the additional things about the A and LA blocks were mine as the bolt pattern's the same. As it turned out, we just got the car running and driving and that was pretty much it. It was surprising how much room the interior had for the size of the car! "Chair high seating" helped in that respect, too.

At one of our Mopar club shows, a guy showed up in a 20-something Plymouth 2-dr. Under the hood was a LA block 318 V-8 2bbl engine. Used the later model radiator hose, too! It was sitting in there "correct" and did look like it came that way. He used the original manual trans, too . . . but he obviously didn't drive it energetically, either. I asked him what it took to do the swap and he replied that it fit together much easier than he would have originally suspected. At least it wouldn't be subject to "tissue rejection" later on!!! I congratulated him on having an engine from the same manufacturer as the car, too.

The street rod vendors have power brake systems for under-floor mounts which probably could be adapted to a Chrysler product. Adding some stiffer springs and shocks, with fresh bushings would firm things up somewhat. The "reverse camber on the outside wheel" is already there, I believe, so adding a "real" sway bar up front should help cornering. Might also be some bigger brakes from a Chrysler station wagon, too, with some upgraded linings? That would leave the steering system to be refurbished and such. So far, all of this stuff would be pretty incognito to the average person.

I'm not sure what it would take to make those Chrysler straight 8s breathe better, but obviously some better intake and exhaust manifolding, plus shaving the cylinder head for higher compression would not hurt. If the compression gets high enough, though, it would also mean a change to a 12V negative ground electrical system. I've never investigated these things, though, on those motors . . . but somebody in the Inliners International club might have.

Just some thoughts,

NTX5467

[Pontiac59]

I still will say the cheapest option to higher top speeds - and one of the easiest - is to get it down to a 3.08 or so final drive ratio. No one will know the difference even if they look under the car. A rearend with no swaybar is all of about 14 bolts, including the driveshaft yoke. Easily changed back to original if you want, too.

I mean, they still used the flathead six through 1959, and by then the cars were built for higher top speeds without a lot of new engineering, so if you copy how those were set up it should be fine.

And I do believe someone, a small cottage industry maybe, is making an adapter to run the Borg-Warner T5 behind a Chrysler six. Not sure if it requires a GM pattern trans or a Ford pattern trans.