Engine/Tranny upgrade swap info on a 1938 Dodge 1/2 ton please

[Dodgefran]

I am not able to use the original L6 engine in my 38 Dodge Humpback Panel truck RC.  I'm interested in finding out what you all used as an upgrade substitute from 70's and up  engine and automatic transmission combo.  I'm not sure what I really want to do so your info is of value to me.  Thanks for your help.

[CarlLaFong]

People on this site usually do not "upgrade" their cars. The focus of the AACA is preserving and restoring old cars. The basic engine was produced until the late 50s maybe later for forklifts, welding machines and other industrial uses. The country is littered with them so finding a good one is pretty easy. As to an automatic trans, that's another kettle of fish

[TTR]

While I've been known to dabble with modifying some vintage cars, I can't offer any useful advise for your intended project, but wouldn't be surprised if you could find better and perhaps more practical advise on some forum where such ("70s and up ...") conversions are more common. This site seems to be more oriented to keeping things original/stock.

 

[Fossil]

My advice is keep it as close to original as possible. I owned a 36 Humped back survivor and never considered altering it. If you do, save everything as it might mean the world to the next owner. I think you'll find that most of the drive train (if it's a 1/2 ton) interchanges with cars of that period. 

[rocketraider]

Sounds like a need for automatic transmission is driving this. As said a Chrysler flathead six is no problem to find, but a compatible AT might be. I don't know if a slant six Torqueflite will work with a flathead.

 

 

[Guest]

 How about a 46 to 48 Chrysler product 6 cyl. with a slushamatic trans?

(semiautomatic)

[Pfeil]

2 hours ago, rocketraider said:

Sounds like a need for automatic transmission is driving this. As said a Chrysler flathead six is no problem to find, but a compatible AT might be. I don't know if a slant six Torqueflite will work with a flathead.

 

 

Although I agree with CarlLaFong that this is not the place on the forum ( Pete should have moved it to the Dodge truck section) ,

 I agree with Rocketrader that the transmission problem is driving it. With that being said you could source something like a 57 Dodge Coronet with a flat six and a PowerFlite automatic which came on those cars.

[Rusty_OToole]

A later, more powerful Plymouth or Dodge flathead six will bolt in. So will the larger DeSoto/Chrysler six, with slight mods to the motor mounts and rad mounting to account for 2" longer engine.

 

The best of the best would be a 1951 - 54 Chrysler 265 cu in 135HP engine with full flow oil filter. These engines were also used as  industrial and marine engines, in Massey combines, and in military Power Wagons up to 1968.

 

Any other engine is a problem because the engine compartment is designed for a narrow straight six. Any V8 tends to be too wide, and hit the steering box. It is possible to get around this by offsetting the engine to the right. I hate to say it but a Chevy small block fits about the easiest of any V8. The Dodge 318 or 360 will also fit but not so easy, starter interference can be eased by using the latest compact starter.

 

The reason for using a V8 would be to have a matching late model automatic transmission. If you can use the stock manual trans, the flathead six would be better and easier, but if you insist on an automatic the V8 is the way to go. A lot more work and expense tho.

 

Warning, do not go too big on the engine or you will overmatch your stock brakes and suspension. Stick with a stock 305, 318, or at most a 350 or 360. Unless you want to do some major mods to the suspension, brakes, rear axle etc.

[Rusty_OToole]

The best advice I can offer is to sell it and buy a later model truck or van that comes with a V8 and automatic. I know it is not what you want to hear, but is definitely the best, easiest, and cheapest way to go.

[TTR]

1 hour ago, Rusty_OToole said:

The best advice I can offer is to sell it and buy a later model truck or van that comes with a V8 and automatic. I know it is not what you want to hear, but is definitely the best, easiest, and cheapest way to go.

… or do the common resto-modification by removing the bed & the cab off the later model truck, cut down or extend its frame & running gear to accommodate the wheelbase needed for the humpback body and mount latter on former.
Done, but then it will no longer be a ‘38 Dodge humpback in other than novelty appearance and will be worth a whole lot less than time and money you'll be spending on it.

Edited September 30, 2021 by TTR (see edit history)

[1939_Buick]

Quote

i am not able to use the original L6 engine in my 38 Dodge Humpback Panel truck RC.

 

Is the reason you want an auto transmission? 

As posts above modifying(=hot rodding) a rare desirable model will reduce its value a lot to those of us who like original cars/trucks. They are only original once.  My view: keep it original (or very close)

 

From posts above to me the width of the chassis limits and easy V8-auto hot rod conversion.

You will not find in USA, but Chrysler Australia manufactured an in line 6 for many years (when Mopar USA was still making the slant 6). Some of these had high performance, equal to mid sized V8's of the time.  Unsure how long these are compared to original 6.

https://en.wikipedia.org/wiki/Chrysler_Hemi-6_Engine

 

A thread with a photo of what is probably this vehicle

https://forums.aaca.org/topic/366086-unloading-a-12-ton-with-no-brakes-from-a-trailer/?tab=comments#comment-2248419

 

Quote

i will be unloading un a storage facility (UHaul)  I don't think they would appreciate any dents in their "Lockers".  I need to control the off load of a 1/2 ton truck with no engine, drive train, or brakes. .......

 

Edited October 1, 2021 by 1939_Buick (see edit history)

[Rusty_OToole]

If it was mine I would either rebuild the original engine or if it was too far gone, like the rod is sticking thru the block, I would get another flathead six and rebuild it. They are a simple engine and parts are available cheap. Vintage Power Wagons has some good buys on parts, but most everything is available from your local NAPA store.

They are a long stroke, high torque engine and don't require much gear shifting. If engine, trans and clutch are in good shape they are easy to drive and have plenty of power for normal use.

[Fossil]

I'm probably going to step on someone's toes here but if you need something modified just go by someone's  retromod. They don't make these anymore and there aren't many originals left. Otherwise Rusty_OToole has given some sound advise. 

[Rusty_OToole]

To clarify, Dodge used basically the same engine from 1938 to 1959 (cars) 1962 (trucks) and as late as 1972 as industrial and marine engines. They all interchange, although there are some minor changes like different water pump, exhaust manifold etc. Plymouth used the same block sometimes with a shorter stroke crankshaft for smaller displacement.

The big DeSoto/Chrysler engine was 2" longer but otherwise similar and will bolt up to the same transmission. Motor mounts and radiator need to be moved forward.

Of course these are all flathead six cylinder engines. They also made straight eights and V8s but we will not go into that.

[Tom Scheck]

Just curious and bit off topic.  Are the "big DeSoto/Chrysler" engines different from the 25" long block?  I have an original numbers matching 1938 RC and it came with the long block.  I believe the 23" block fits without any modifications but has visible differences, especially the exhaust manifold.

[Rusty_OToole]

The big DeSoto/Chrysler engine is the 25" long block. The regular Plymouth/Dodge engine is 23 1/2" long, measured at the head.

Canadian made Plymouth and Dodge got a version of the 25" block with bore and stroke reduced to give the same displacement and HP as US models. There was a reason for this. Chrysler Canada got its own engine foundry in 1938 but they were equipped to make one engine and one engine only, the 25" long DeSoto/Chrysler six. To get an engine suitable for Dodge and Plymouth they altered it accordingly. For example the DeSoto/Chrysler had a 3 7/16" cylinder bore, the Plymouth/Dodge was 3 3/8. Then they used different stroke crankshafts for 201, 218 and 230 cu in displacement.

So, if you have a Plymouth or Dodge made in Canada the big Chrysler engine bolts right in. And a Canadian Plymouth or Dodge block can be bored to 3 7/16 and the Chrysler pistons crankshaft and rods installed turning a 217 engine into a 265.

 

Careful reading of spec lists reveals that Canadian and American 217 and 230 Plymouth and Dodge engines have different bore and stroke, the Canadian engines with bigger bore cylinders and shorter stroke.