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41 Plymouth SB Mopar Engine Swap

Discussion in 'The Hokey Ass Message Board' started by rockable, Aug 1, 2010.

  1. rockable
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    rockable
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    I've been working on my Plymouth but haven't posted lately. Nothing I'd done seemed worth the effort to post. :)

    This weekend, I finally made some progress. I purchased a 360 a couple weeks back and this weekend I made and installed the mounts. First, I set the engine in place a couple of times and after making a relief in my firewall, I settled on a position for it.

    Once I didn that, I created some paper cutouts of the engine mount brackets, then transferred the design to some 1 1/2 X 3/16 flat stock. After cutting them out, drilling them, etc., I bolted them to the motor mounts and made some small adjustments.

    Next, I tacked them in and double checked the fit all around. The engine is offset about an inch to the passenger side and I'm using 340 exhaust manifolds to wrap around the steering column. This is one of the tightest areas.

    Hopefully, the pictures will tell the rest of the story.

    Attached Files:

  2. rockable
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    rockable
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    Second set of pictures.

    Attached Files:

  3. moparron426
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    moparron426 Member

    Looks great so far, keep up the good work:cool::D Ron...
  4. mopar4life
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    mopar4life Member

    Nice mounts. whats going on for the tranny mount, and what tranny?

    I gots me a 47 dodge with LA/904. someone else did swap (never finished) I'm brainstorming master/booster and tranny mount. stock master fits but I really want dual master and booster.
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  5. rockable
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    I'm planning to put an AX15 and Dakota rear in it. That's next weekend. :) Most of the junkyards around here aren't open on Saturday, so I'm taking a day of vacation on Friday to go try to round up all the goodies I need.
  6. Rodhotz
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    Rodhotz Member

    Try a explorer rear end, it is the same width and gives disc brakes and posi.
  7. need louvers ?
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    need louvers ?
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    The swap is looking good! the only thing I might add, and you might already have this planned, why not "box" those mounts on the inside open sides to give them a bit more fore to aft rigidity. 340 exhaust manifolds are the way to go, rare these days though, so good score! You'll love this thing when your done. These are the most comfortable pre 48 cars ever.
  8. Seepwater
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    Seepwater Member

    I put a 318 in a 37 Plymouth. Found some center dump exhaust manifolds and milled them at a slight angle to make tighter 'block huggers'. Gave me lots more room!
  9. need louvers ?
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    Seepwater, that's exactly what I did with my 360. Then I hand "ported" them,, sent them to Extrudehone over in CA, etc, etc. No kill like overkill.
  10. JoelOkie
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    JoelOkie Member

    Looks great Rock. Damn nice job. I hope I get to take a look in person next Saturday morning. Joel
  11. 69fury
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    69fury Member

    Looking good! Definitely box those mounts- it is SOOOO easy to make some good power with the LA mills- I've got a 360 based 415 in my Falcon gasser build.

    Yours should be a comfy, smooth, cruiser with some nice power. Not every car must have unreasonable power, but I would never put up with a wimp that is only a pretty face. If I put my foot down, shit better happen now. So I make sure it wont break itself with its own performance. (box mounts,lol)

    -rick
  12. farmer12
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    Great work Rock! Glad to see you got the engine in there, the boxing of the mounts has already been mentioned, that will certaintly strengthen them. How much clearance do you have between the steering column and the exhaust manifold? Couldn't see it from the pics. Good to see you've started a thread, nice work Rock! Subscribed. Good luck, Eric.
  13. FinnishFireball
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    1. Scandinavian HAMB'ers

    Looking good Rock!
  14. Spanish Fly
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    Spanish Fly Member

    sweet look good.....................................nice job
  15. George
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    George Member

    There's been threads on the tranny mount before. Easiest is (truck?) mount the goes down & uses a crossbolt. Fab a 2X2 crossover, then weld ears that go on either side of the crossbolt, insert bolt, done!
  16. rockable
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    "Box the mounts" - Damn, I knew that I should have dones something else before I slapped paint on those. :) Oh well, I 've got more paint.

    There's enough clearance around the manifold and steering column to get your fingers in there, Eric. The rear of the manifold will probably be something like 1/4-3/8", depending on tranny mount.

    I lucked up and found a set of 340 exhaust manifolds on craigslist for $350. They were perfect for this swap.
  17. RodStRace
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    Looking good! For the trans mount, I used a 91 Dakota 2wd crossmember and a couple plates. Bolted it up to the trans, marked and cut it to width with the plates held to the X member, then welded the plates to the cut crossmember. A couple bolts on each side finished it.

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  18. Country Gent
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    Country Gent BANNED

    Looking good. Glad to see Mopar into Mopar. I kow you spent $350 for manifolds butMAYBE and I say Maybe 70s-80s Dodge pickup headers for small block could work. I have a 74 power wagon with a 360. Headers hug pretty close in. Just a wild thought.
  19. 4woody
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    4woody Member

    I know that the passenger side of the firewall usually gets dimpled with these swaps, but I don't understand why it is only that spot on the passenger side.

    Is the engine set at an angle to clear the steering column, and that puts the passenger side closer and the driver side farther from the firewall?
  20. George
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    George Member

    just the way it works out, 1 dent & both inner fender cut a bit.
  21. RodStRace
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    RodStRace Member

    4woody, I didn't have to ding mine. Right side head is further back than the drivers side, like a SBC. SBF is opposite. Firewall is pretty even on both sides. There is a bit of an angle, but the tailshaft is offset some too, so it's not much.
  22. rockable
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    The head on the passenger side extends back further than the head on the driver side. Plus, I'm trying to get it back as far as I can for radiator clearance and better weight distribution.
  23. George
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    George Member

    On the 46-8s you can reverse the radiator frame, that moves the radiator forward a few inches.
  24. plmczy
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    Lookin good Rockable. I used the drop out trans mount from a 79 chrysler LeBaron and 2 pieces of 2"x2" square steel tubing. That way if I ever need to drop the trans for work I pull out 4 bolts and lower the tailshaft. I'm using a 904 in mine not sure how the newer ones attach. I'd have to crawl under my dak and take a look. You guy's have me worried about my engine set back now, I have about a finger width between the firewall and valve covers on my car. later shawn
  25. need louvers ?
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    need louvers ?
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    The only thing that I worry about with the dropout style trans mount is it does nothing to stiffen these cars up. I had a simple 2" x 2" crossmember welded across the frame rails on mine for the first 12 years or so, and it flexed so much it would open the doors going into cambered driveways. I replaced it with a tubing X-member made of 1 3/4 .120 wall stock with a dropout adjustable trans mount, problem solved. That said, I can't remember if the '41 has an X member or not, so it might be a moot point.
  26. George
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    George Member

    One member here didn't box his '41 & he has a 354 in it.
  27. need louvers ?
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    I honestly can't remember if the '41 has an x or not. I do know that my budddy's ,41 DeSoto that I will be doing this in soon, does. If it does, build a dropout and be done. If it doesn't, think twice about a drop out and think more about a solid cross member that goes side to side.
  28. rockable
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    The 41 does have an X in the chassis. I have removed the original cross member. The new one will be substantial enough. I like tubing.

    The motor mounts do not lend themselves to boxing, as the rears are welded to a straight section of frame and the fronts welded to a section that is turned in. Therefore, they are in different planes. Do I really need to stiffent them front to rear? If so, I can gusset the front mounts but I don't really want to.

    The 41 radiator cannot be reversed without hacking the fenders. I'll likely put a Mustang radiator in it. That way, I can position it however I want it.
  29. need louvers ?
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    It would be best if you can. Just be super careful to retain as much of that X as you can. The '42 - '48 is basically the same frame, but for some reason they lost the X in those years, and did a simple straight cross member for the trans. I duplaicated that design with mine, which meant I had to pull the engine to get trans on my car originally when I built it. It wouldn't even keep the doors closed when I was really pushing it. I built a tube X member when I redid it about five years ago, and it made all the difference in the world. Just something to think about.
  30. RodStRace
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    RodStRace Member

    Need louvers knows these cars, but the 40-41 does have a pretty beefy X member.
    When I built mine, it was before chassis detail. The thickness of paint made the fabbed trans mount a very tight fit.

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