251 engine in a 34 plymouth

I have a 34 plymouth,that I want to put a 251 engine in it.What do I need change ? I read that the bellhouse didnt fit.From the 34.

regards michael

A DeSoto or Chrysler 251? That would be a 25" long block replacing your 23" long original Plymouth engine? I don't know what that would entail but suspect you are in for some major modifications of the engine mounting system and firewall.

It is possible to put a later Plymouth or Dodge 231 engine into the car with the main issue being the fit of the starter motor.

Chrysler 251,yes I saw it was longer.But do I come closer to the firewall ? thought it only was a problem in the front.

Been a while since I looked that closely at a '34 but on my '33 which I think is very similar there is only a fraction of an inch clearance between the fan and the radiator. Which means the radiator would need to be moved forward. But it is already on the forward most frame cross member and is tightly integrated with the radiator shell assembly. So going forward would probably be a bigger problem than going backward in the engine compartment.

Later cars (after '37, '38 or maybe '39) when the Canadian "Plodges" (Plymouth cars badged in Canada as Dodge) were built using the 25" long engine built in the Windsor plant the lore has it that you can simply reverse the radiator mounting bracket to put the bigger engine in. However I've heard of people with 1940s Plymouths who needed to do some frame surgery to make it work. For the early '30s L-6 engines I think you are looking at a big set of fabrication issues. Big enough that if you are asking on this forum that you may not be ready for this type of thing.

Also, for what it is worth, that type of modification would dramatically reduce the value of the car to a person like me.

Starter to block interference is a big obstacle when attempting to replace 1933-34 Dodge/Plymouth six with 1935 and later engines

The reason I ask here ,was to save time as I dont have asses to a lot of plymouht parts here.value is not a problem for me,I will build the car as I like it.Got plenty of original cars,but would hate to cut in the firewall.When I bought the car,there was no engine in.Only the gearbox with out the bellhouse.Then I found the 251 ,and thought I could use it.Else it seems that it would be eassier with a ford flathead v8 to put inside.

Here is a photo of my plymouth

You sure that is a '34? Front fenders, hood, radiator shell and front axle look more like '33 to me.

What is the serial number on it? (If North American built it should be on the right door hinge post.)

Where are you located that Plymouth parts are harder to find than Chrysler parts?

I was told it is 34,the front axle is a tube style.On the firewall is a tag saying:PD 2745cc. and this number is stamped into the firewall next to the coil 4619.Are this any of the serial number ?

Located in Denmark (europe).

I was told it is 34,the front axle is a tube style.On the firewall is a tag saying:PD 2745cc. and this number is stamped into the firewall next to the coil 4619.Are this any of the serial number ?

Located in Denmark (europe).

The number on the firewall is the body number which is different from the serial number which should be on the door post. And both are different from the engine number which is on the block just above the generator.

But in this case the body number answers the question: Your car body PD2745CC is the 1745th Convertible Coupe of the PD engineering code to be built. (They used sequential numbers for each body style starting with 1001.) PD is one of the engineering codes for Plymouths built in 1933, the one sold under the name of "Deluxe Six". So your car, at least the body, is a '33. That tubular front axle is also characteristic of the '33 models as well as the shape of the front fenders so it is very likely a '33 frame too.

Super,

and thanks for you info,now I know a lot more.It seems like that there never has been any serial number on the door post.There is a plate on the firwall that tell it was built in USA.Do you know from which years periode I can use the bell house.That will fit the 251 on my 33 gearbox ?

Don't know the answer to the bell housing question. As I understand it any of the 23" long Dodge or Plymouth blocks up into the 1950s should bolt on to the '33 bell housing with the only issue, as dep5 mentioned, being the clearance for the starter.

But I don't know anything about the bell housing for the bigger Chrysler or DeSoto engines. The one install of a 251 engine into a late '40s Plymouth that I've seen photos of makes it look like the bell housing for a DeSoto was used. But I really don't know.

The number on the firewall is the body number which is different from the serial number which should be on the door post. And both are different from the engine number which is on the block just above the generator.

But in this case the body number answers the question: Your car body PD2745CC is the 1745th Convertible Coupe of the PD engineering code to be built. (They used sequential numbers for each body style starting with 1001.) PD is one of the engineering codes for Plymouths built in 1933, the one sold under the name of "Deluxe Six". So your car, at least the body, is a '33. That tubular front axle is also characteristic of the '33 models as well as the shape of the front fenders so it is very likely a '33 frame too.

In addition, side splash aprons with the access hole at the rear, 33 not 34; passenger door with no hole for the lock below the handle, 33 not 34; wheels, hood, fenders all 33 not 34. Nice looking 33 though.

Glaser31, I have a 34 Plymouth but original and restored but cracked block. Do you have the old engine from your 34 if so would you sell? John in England

hi John,

sorry to tell you.But there was no engine with my car when I bought it,thats why I want to upgrade it.But I will keep a eye here for a engine,and let you know if I find one.

regards michael