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Customs Mopar L6 engine swap

Discussion in 'The Hokey Ass Message Board' started by flatordead, Nov 11, 2014.

  1. What does it take to put a Chrysler industrial engine in a 1941 Plymouth?
    The engine block casting number is 870729-8. Bell housing and flywheel are missing.
    Does the plymouth housing and wheel fit?
     
  2. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,971

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    If the "Chrysler industrial engine" is indeed based on the longer block used in Chrysler and DeSoto vehicles, then you will need to move the radiator forward a couple of inches.

    However, so far as I know, the name "Chrysler" was applied to all versions of their industrial and stationary engine offerings even when based on the shorter Ply/Dodge blocks. So, if I am correct about that, the first thing to do is measure the block/head length. The shorter is 23" and the longer is about 25".

    In either case, the bellhousing should fit the block. The flywheel interchange will depend on the number of crankshaft flange bolt holes. If you flywheel bolt pattern matches, use it. If not, you may have to source a different flywheel, but over the many years of Mopar flathead six production, there is something out there that fits. I wish I could be more specific about which, but it's been a few years since I did something like this and I am rusty on the details beyond what I have said here.

    I did put a 265 Chrysler 6 in a '51 Dodge years ago and in that particular case, had to notch the front crossmember for pan clearance, but it was a relatively minor amount and easily accomplished. I would expect you will find a similar interference if you have the longer engine. Best wishes with your project.

    Ray
     
  3. Ray thanks for all the information. It is indeed a 25"long engine with a 8bolt flywheel flange.
    I will try to post some pictures of the said engine soon.
     
  4. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 923

    Flat Six Fix
    Member

    Hnstay gave great advice, and you can go to this webiste for a whole lotta of info on these cars/engines, and the swap you mention.
    www.p15d24.com
     
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  5. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 923

    Flat Six Fix
    Member

    Hi Ray, when you did that 265 engine swap, did you notice a whole lot more get up and go with the 265 versus the 218?
     
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,503

    gimpyshotrods
    Member

    Don't forget, these also did not have terribly high compression (often around 7:1). Milling the head is a simple and inexpensive step that can get you some HP and TQ.
     
  7. Hnstray
    Joined: Aug 23, 2009
    Posts: 10,971

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    Well, yes I did notice an improvement, but it wasn't all from the extra cubic inches. The Dodge had 230 engine (stock for that year), but I also removed the original Gyromatic semi-auto and installed a 3 speed manual with overdrive from a '53 Dodge. The '53/'54 only manual trannies have a loooong input shaft to reach the clutch when the fluid coupling is absent.

    The O/D compensated nicely for the 3.90 (I think) rear end gears for highway use. All in all, made for a nice driver with some pep too.

    Ray
     
  8. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,994

    Rusty O'Toole
    Member

    If your Plymouth was made in Canada, it will fit right in. Many export cars were sourced from Canada, especially those sent to British Commonwealth countries like England, Australia, South Africa.

    The US factories made 2 different 6 cylinder engines. A smaller one, measuring 23 1/4 inches at the cylinder head. This was used in Plymouth, Dodge, and Dodge trucks. And a larger one, measuring 25 inches at the cylinder head for Chrysler, DeSoto, and some large Dodge trucks.

    The Canadian factory , from 1938 onward, used only the larger engine. But they made versions with smaller bore and stroke, for Plymouth and Dodge.

    Therefore the large engine fits the Canadian made cars perfectly. On US made cars you will have to move the motor mounts forward and move the radiator forward. On some cars the frame is already drilled for the new motor mount location.

    There are also variations in the number and location of flywheel bolts, and the location of the starter. The bellhousing will bolt on and if you are lucky, the flywheel and starter will fit as well.

    What is the engine number stamped on the upper left front corner of the engine block? There is a raised pad above the generator, just below the head. This is the only way to identify your engine for sure.

    If you have taken the pan off, the 265 has distinctive connecting rod bolts with no heads. This was done for clearance and these bolts were used only on the 265.
     
  9. Thanks guys for all the information.
    The casting number on the block is 870729-8. I did a little google on that number and it turned out a that a 1942 build fire pump used the same block.. So I would say that block is made around 1941/42.
    The stamped Serial number is III 8 86922.
    I can borrow an early 40's Dodge bell housing and flywheel next month from a buddy and will see if the wheel and housing fits the Chrysler block and if the starter lines up.
    I'm not so concernd about radiator and motor mount modifications, but the bell and flywheel interchange makes me worry a little.
    Did also check the Hollander but it did only refer to flywheel/clutch variations.
     
  10. 73RR
    Joined: Jan 29, 2007
    Posts: 6,253

    73RR
    Member

    One clarification needs to be made regarding the flywheel. The 23" Plymouth 201-208-218 flywheel has a different amount of offset at the crank compared to all other flywheels. The little Plymouth crank flange project 1" +/- from the block and all others are at 1.1875" +/- so if you use the 218 wheel on another engine the starter will be 3/16" deeper into the ring gear. MotherMopar modified the flywheel so that the bellhousings could interchange.

    .
     
  11. Canadian built cars generally have an aluminum Vin tag while US are often stamped steel. Canadian ones are stamped like you would with hand stamps while US are more machine style embossing. It might not be a hard fast rule but so far I have not seen a variant myself.
     
  12. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,994

    Rusty O'Toole
    Member

    Serial number should start with a P for Plymouth, D for Dodge, T for truck, S for DeSoto or C for Chrysler. Could also have IND for industrial engine.

    This site can help you identify your engine.
    http://www.t137.com/registry/help/otherengines/otherengines.php

    They identify the IND 8 model as an early 251 cu in industrial engine.

    You can check the stroke without removing the head. There is a small pipe plug in the cylinder head, over the #6 piston. Remove this plug and you can drop a screwdriver down onto the piston. Turn the engine slowly, mark the screwdriver at the lowest and highest positions and you can measure the stroke. If you use a wire for this be sure to bend a loop in the top so you can't drop it inside the engine.

    If it has a 4 1/2 inch stroke it is a 251, 3 7/16 X 4 1/2 bore and stroke.

    All the Chrysler and DeSoto engines had 3 7/16 bore. They also made a small bore, 3 3/8 block for Plymouth and Dodge. These came with 4 1/16 or 4 1/8 stroke.
     
  13. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 8,994

    Rusty O'Toole
    Member

    These are a powerful, well made engine, very smooth and quiet with plenty of torque. They had such "modern" features as insert bearings, full pressure oiling and full flow oil filters long before their main rivals Ford and Chevrolet.

    If the engine is in good shape you will have plenty of power for your light weight Plymouth and if you desire a little extra, there are some ways to hop up your engine at low cost.
     
  14. Does anyone know if anyone wants a chrysler marine manifold? It was designed as two in one intake and exhaust, and it's updraft.
     

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