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pyrodork

straight 6 engine swap... 23" to 25"

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i have a 37 plymouth with a bad engine. i thought about repairing/rebuilding, but 1) i've never done that before and 2) money, tools, money... money.

anyway, i found a rebuilt desoto engine for a price i'm willing to pay. the only thing is, my current engine is 23" long (likely the 201... but i'm not exactly sure... long story), and the desoto engine is 25" long (236.6?). i currently have no extra clearance for a longer engine.

i have heard a trick about reversing the radiator housing to provide the extra room needed, but just by visualizing it, i can't see how that would do anything. does someone have the experience of doing this; maybe even a website tutorial with pictures? or am i just out of luck until i find a 23" block?

thanks!

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Check out this website P15-D24 Homepage , others have done this very swap, with some modifications it can be done.

Interestingly, in Canada, all Mopars cars and trucks had 25 inch flathead 6s, they did not market or make the 23.5 inch 201,218 or 230s, they had 218,228,237,251,265, all with a 25 inch block.

You will have to move your front motor mounts forward, and somehow move the rad ahead, or eliminate the fan, and go with an electric pusher fan, which you can buy in the 6 volt type if you need.

The 251 will give your Plymouth some extra boost, having probably an extra 30-40 HP, that you will notice.....

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joe, you are a bit far from me, but i'll keep that in mind.

fred, i've been searching that website for hours. all i see is reference that people have done it and that a "quick search" should pull up any info needed. i haven't found a thing relating to the 23 to 25 swap. having to do that stupid "captcha" every time i want to do a search is giving me a headache.

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joe, you are a bit far from me, but i'll keep that in mind.

fred, i've been searching that website for hours. all i see is reference that people have done it and that a "quick search" should pull up any info needed. i haven't found a thing relating to the 23 to 25 swap. having to do that stupid "captcha" every time i want to do a search is giving me a headache.

Contact Don Coatney, on P15-D24 he has done this very swap, He can give you some info with substance on this topic...........Fred

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That swap is apparently much easier on vehicles that were sold in both the US and Canada after Canadian engine production started. However for a 1930s Plymouth I think there would have to be major changes made to the car to fit a 2" longer engine under the hood. For one thing, pre-1939 or so, you can't just flip the radiator mount around and the front frame cross member would probably also need major surgery.

You can bolt any 1933-59 US built Plymouth or Dodge 6 cylinder passenger car engine into your car without modifications and there should be plenty of those still available. I'd pass on trying to put that DeSoto engine into your car...

If you care about judging, the Plymouth Owners Club will check the engineering code on the engine, so you'd want an engine with a number starting with P4. Not sure about AACA as the judges there might not know what to look for.

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If it were a Canadian 37 Plym or Dodge, which shared the same body, in Canada, it would have come witha 25 inch engine.

So yours beinga ply, this could be doable, exactly whats needed, will be your research to find out.

The idea of going toa say late 50s, 230 23.5 inch engine could be great, as those came with cloes toa 130 hp stock, witha higher compression ratio to boot. You would notice some more pep with that.....

PS go non P15-D24, and post some questions, lots of traffic on there, with a lot of knowledgable Guys...

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just out of curiosity, if i'm going to change the engine out, how hard would it be to change to a 318, 340, 360 instead? motor mounts are obvious, but i'm more worried about electrical, gauges, pedals... overall functioning. i often find these with small block 340/360 mopar engines in them, but not up close so i can examine.

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Steering box is usually in the way. The smalll block A' body used an exhaust manifold that rises up to clear the OEM power steering on the driver side that might help. I think you will still need to offset the engine a bit.

It is no big deal to offset the engine as long as the centerlines of the crankshaft and the pinion shaft are parallel. (both up and down and side to side). If you try to aim the engine at the rear end you will get a vibration.

If you are going in that deep why not look into a Mustang II or a Fatman IFS kit.

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eventually, but one thing at a time. the guy i bought the car from had a 340 or 360 with j heads he was going to put in it. plus 2 4-speed trannies and a rear end from a 73 challenger for $600. not sure if he still has them, but if i'm going to spend the money, why don't i spend it on something bigger?

alternate plans are to either get that desoto engine or resleeve the cylinders in the one i've got and put in new rods and pistons. i started thinking about the bigger engine because if i get the bigger desoto (ideally because of slightly more hp), i'll have to modify things anyway. might as well get an engine that will give me a lot more hp, right? it makes sense to me.

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One thing at a time may work for you, but remember that one thing leads to another.

There would be an order to things, no sence in building your motor mounts if you are going too change suspension later.

If you are going to race the thing then by all means get the highest HP that you can. I have built several of these things and I like four speeds. The problem with a built engine and a manual tranny is the drivability. Cammed up motors with manual trannys dont go slow very well. So if you are doing parades or drive thru car shows they are a *****.

The Hemi in my 28 Dodge wont travel at idle as the cam gets to violent on the running gear so clutch in, clutch out constantly. I have a couple of cars that do this and I make my kids drive them.

Here is a picture of three of my cars inside the Oregon State Pen. They do an invitational car show every June. I made the daughters drive...HA-HA.

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If it were a Canadian 37 Plym or Dodge, which shared the same body, in Canada, it would have come witha 25 inch engine.

So yours beinga ply, this could be doable, exactly whats needed, will be your research to find out.

The idea of going toa say late 50s, 230 23.5 inch engine could be great, as those came with cloes toa 130 hp stock, witha higher compression ratio to boot. You would notice some more pep with that.....

PS go non P15-D24, and post some questions, lots of traffic on there, with a lot of knowledgable Guys...

No, Chrysler Canada did not open their engine plant until late 1937. Thus 1938 and up Canadian-built vehicles used the 25" block. 1933 to 1937 Canadian-built Plymouths used American-built 23" block Plymouth engines.

Bill

Toronto, ON

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One thing at a time may work for you, but remember that one thing leads to another.

There would be an order to things, no sence in building your motor mounts if you are going too change suspension later.

If you are going to race the thing then by all means get the highest HP that you can. I have built several of these things and I like four speeds. The problem with a built engine and a manual tranny is the drivability. Cammed up motors with manual trannys dont go slow very well. So if you are doing parades or drive thru car shows they are a *****.

The Hemi in my 28 Dodge wont travel at idle as the cam gets to violent on the running gear so clutch in, clutch out constantly. I have a couple of cars that do this and I make my kids drive them.

Here is a picture of three of my cars inside the Oregon State Pen. They do an invitational car show every June. I made the daughters drive...HA-HA.

wow! let's see that rat! (i'd like to hype up my new 29 {maybe 30?} rusty ford stakebed at a later point in time; as 45mph top speed isn't too thrilling on the highway (actually found a 100hp late 40's ford flathead v8, stuck, for $100 that i'm thinking about), but i'd really just like to get her moving right now. same with the plymouth, for that matter. eventually planning to make a roadster stakebed with a folding top (but $$$$$$$$)!

i do like speed... so maybe upgrading the suspension on the plymouth is ideal? or just throw an engine in there to have fun while budgeting for the big deal? thing is, i have to throw a lot of money down regardless. maybe modify the motor mount now and upgrade the suspension when i can afford it? i don't mind the clutch up-down so much.

question remains, though... would it mostly be upgrading the throttle linkage and electrical to make it work once it's in? i honestly have no idea.

Edited by pyrodork (see edit history)

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Yes, I would think that a later model engine would prompt you to go to 12 volts. (another can of worms) Like I said, one thing leads to another.

Trying to drive while building does not work, (for me at least).

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post-52542-143138853299_thumb.jpg

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If money is an issue think carefully about making any changes. It may look cheaper but it won't be because one thing leads to another.

The cheapest way out would be to rebuild the engine you have or if the rod is sticking through the block, find another Plymouth/Dodge engine. They aren't that rare and a lot of guys are changing them out.

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I can certianly appreciate that one has to be funded to have fun with these old cars.

You must pay to play !!

Wheather its in parts OR labor OR time. (mostly all three)

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The cheapest way out would be to rebuild the engine you have or if the rod is sticking through the block, find another Plymouth/Dodge engine. They aren't that rare and a lot of guys are changing them out.

i think that's what i'm going to end up doing. the block looks good, but i gotta loosen up the crank to get that bent rod out. i figure that i'll at least get the one cylinder resleeved (or should i do them all at once?), new rods/bearings/pistons/rings/gaskets... then see where i end up.

as a backup, i found someone nearby selling a block, but he hasn't had any bites in a year or two.

i'm kinda stuck on which parts to get, though... since my engine does not appear to be original. that "specify model 219" tag is getting to me, too, since i'm aware of a 218 engine, but not a 219.

can't really work on the ply so much right now. got a model AA ford i'm trying to run (not drive right now... just run!). those tire/tube assemblies get mighty expensive when used isn't really an option! money is still tight... but on the bright side, i should have a college degree in june!

Edited by pyrodork (see edit history)

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i think that's what i'm going to end up doing. the block looks good, but i gotta loosen up the crank to get that bent rod out. i figure that i'll at least get the one cylinder resleeved (or should i do them all at once?), new rods/bearings/pistons/rings/gaskets... then see where i end up.

as a backup, i found someone nearby selling a block, but he hasn't had any bites in a year or two.

i'm kinda stuck on which parts to get, though... since my engine does not appear to be original. that "specify model 219" tag is getting to me, too, since i'm aware of a 218 engine, but not a 219.

can't really work on the ply so much right now. got a model AA ford i'm trying to run (not drive right now... just run!). those tire/tube assemblies get mighty expensive when used isn't really an option! money is still tight... but on the bright side, i should have a college degree in june!

"model 219" refers to a model number given to an engine, less accessories, by the parts department. If, say, 1949 through 1953 Plymouths used the same engine, although the Plymouth model numbers change each year, the engine model number would be the same. "Less accessories" means no manifolds, generator, carburetor, wiring or oil filter.

I have a number of Canadian parts books, but Chryco did not start listing the model numbers until 1951. The lowest model number listed in 1951 is model 222, used on US built P22, P23, D39, D40, SP22 and SP23. Canadian-built versions used model 401 engines. Model 222 is also listed in the 1953-54 parts book for the US-built 1953 and early 1954 Plymouth.

The tag also means the engine was rebuilt, or at least part of it was. Will have to determine what size a model 219 is and that will help determine the con rods, etc. needed. For the pistons, determine the diameter of what you have now. The cylinder bores should be 3.125" or 3.25". Anything slightly larger will tell if the cylinders have been bored, and by how much.

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"model 219" refers to a model number given to an engine, less accessories, by the parts department. If, say, 1949 through 1953 Plymouths used the same engine, although the Plymouth model numbers change each year, the engine model number would be the same. "Less accessories" means no manifolds, generator, carburetor, wiring or oil filter.

I have a number of Canadian parts books, but Chryco did not start listing the model numbers until 1951. The lowest model number listed in 1951 is model 222, used on US built P22, P23, D39, D40, SP22 and SP23. Canadian-built versions used model 401 engines. Model 222 is also listed in the 1953-54 parts book for the US-built 1953 and early 1954 Plymouth.

The tag also means the engine was rebuilt, or at least part of it was. Will have to determine what size a model 219 is and that will help determine the con rods, etc. needed. For the pistons, determine the diameter of what you have now. The cylinder bores should be 3.125" or 3.25". Anything slightly larger will tell if the cylinders have been bored, and by how much.

that's interesting! it's odd, though, from the history of the vehicle i've received. regardless, i gots what i gots.

sounds like my 219 may be late 40's to early 50's. judging from a photo i took a few months ago with a tape measure, the bore size appears to be 3.25". my photo doesn't show the measure going to exactly 3.25, but it's close enough to determine. it shows 3 3/16" but not counting the extra mm's that the tip of the tape gives you.

now to find out exactly what size the 219 is. my carter carb model is D6G1, which did cause a problem when i ordered a rebuild kit for a 37 plymouth. i'm not sure if that gives any kind of hint, but perhaps it was a package deal with the engine and the carb was always with it?

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A list of carburetors I have shows the D6G1 being used on the 1946-48 Plymouth P15 models.

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