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Engine swap

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Cool looking car!

 

My truck has a front disc conversion from TSM and I am very satisfied with it.  It was easy to install and stops the truck well even with no power booster. They (TSM) show both front and rear conversion kits on the web site that look to fit your application. There are other kits out there as well,  I am sure more folks will chime in.

 

The fellas on this site run a little on the Mopar purist side, so expect getting the business about a Chevy swap.  I am largely in this camp;  GM stuff is well and good but keep your Mopar a Mopar.  There's plenty of good chryco engines to play with if the rugged old flattie just doesn't do it for you.  Heck, I'd rather see a Jeep 4.0 L6 under the hood of a Plymouth than a boring old tree-fiddy chebbie!

 

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I am having 5.3/4L60e installed in a similar car, 37 Dodge 4 door sedan.  

 

Its tight.   Probably some similarities to your 350 swap.   Thoughts as follows:

 

We used fatman Mustang II style suspension and crossmember with 2" raised spindles for a near factory ride height.   Both it and the frame needed notches to clear some components, like the low mounted ac compressor.   Exhaust and steering is tuff to route as the frames are very narrow.   Fatman crossmember is supposed to be a direct fit but still takes a LOT of work to fit to the humped dodge/Plymouth frame (you must make up the round top panels to weld the member up under the humps...much cut and try).   The original front suspension and steering, in good shape, should be (and positively reported on HAMB and AACA) fine with a 350, still, plan for exhaust and steering box fitting issues.  And note, the original steering and suspension leaves you with 80+ year old non power steering system.   Hard to fix on the road if a part breaks.

 

The factory boxed front portion of the frame was pierced and then motor mounts inserted and welded for the 5.3L.   Not sure if the 350 can use some bolt on style or if the motor mounting points are even the same.   I believe the LS motor mounts are further back than the earlier gen 350s.

 

Engine will sit low in the frame, fan will be covering the bottom half of the radiator.  But the rear sump LS pan leaves good ground clearance on a factory ride height car, I used 2" raised spindles since I don't want it looking slammed.   Its a resto mod.   A lowered car, I can't say what pan to ground clearance would be, but with an LS I suspect it'll be worrisome.

 

   I believe you can easily move the radiator forward an inch or two, we are exploring that now....though it looks like the engine and fan are far enough back for a factory install of the walker radiator.   If its too close, we'll simply push the radiator forward in the nose.   In any event, the 5.3L did not require any modification of the factory front brace to which the radiator and nose bolt.

 

I suspect we will have to ditch the inner fender wells to accommodate the exhaust, but are exploring block hugger headers to see if we can dump exhaust within the narrow frame rails and still clear the steering shafts.   If not, I imagine we will toss the inner fenders and take headers out over the frame and then back under.

 

Either suspension, plan to fit up ford or Gm power disc brakes on the front.  The old manual Lockheed drums will not be up to the job in modern traffic with the much increased hp and torque from a v8.

 

You may well have to notch the firewall to move the engine back.   We had to with the 5.3l, (About 4+ inches over the full width of the engine) I assume the 350 block will be similar length to the 5.3L and will add issues for the rear mounted dizzy on the earlier generations of 350.  I do note the 5.3L appears about 3 or 4 inches wider than the earlier generation small blocks.  

 

The 4L60E needed a larger center hump for the floor pan and half moon cut in the fire wall notch to clear the bell housing.   Assume same for the TH350.  However, we will be using a lokar floor shift and ebrake handle in the floor to retain some original look.  We have not explored whether the original mounting holes are in the right spots yet.   If not, will weld them up an cut new holes.  

 

The 4l60 needed a notch in the passenger side x member to fit, but otherwise, we retained the x member and driveshaft loop with no issues.   Assume similar for the TH350.

 

We placed a gm Pontiac LeMans rear end on the original/nos semielliptic rear springs.   Good fit. Simple swap of the spring perches and bolt it in.   Planning to run 600x16 for original look so no clearance issues and better rear brakes with e brake hook up.  You'll want to do similar since I don't know how the original dodge rear will react to a doubling or tripling of horsepower and torque that comes with a v8.  Your original rear axle is probably 4.1/1 ratio and 10 spline shafts.    About any modern axle with fine spline axles will be much stronger not to mention giving you the option for much more suitable gears for highway travel and the ability to add a posi unit.

Edited by Sharps40

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I'm sure you've thought about this, but why not put a 318/360 into it rather than a Chevrolet? When you go to sell it, a true mopar person won't give it another look if you put a Chevy in it. Just my opinion. I have a '48 Club Coupe and am in the process of putting a 360 into it. You can get a kit so that everything works with your stock frame. No fabrication or cutting. You will have to weld the mounts in, and drill holes for the cross member but in the long run it's a pretty simple deal. Just a suggestion, and good luck.

 

Edited by modracr41

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Go to “butches cool stuff” I recently purchased a kit for sbc and turbo trans for my 51 coronet , looks pretty straight forward even offset engine and trans 1” so can use original steering. I haven’t installed yet and was actually hunting around on here to see if anyone else has used this kit and has installation pics or had any issues with installation 

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Butches Also sell the install kit for small block Mopar motors.

 

Maybe they will do an exchange Chevy for mopar kit??  😉

 

DJ

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On 7/24/2019 at 5:51 PM, falconvan said:

Don’t do it!! I put a Chevy in my 48 Plymouth and the Mopar gods have cursed me ever since!

I’m already in too deep to turn back now lol do you have any pics of motor mount locations ? Seems to me ,to get a decent motor trans degree 3-5* motor sits fairly low in chassis ? 

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On 7/27/2019 at 11:29 AM, Davknz said:

I’m already in too deep to turn back now lol do you have any pics of motor mount locations ? Seems to me ,to get a decent motor trans degree 3-5* motor sits fairly low 

Can't get pictures to load but I had to flatten the firewall plus I went to a Cavalier rack and pinion. I had a 5.3 in it but after it ate the cam I went to a standard 350 Chevy crate motor.  If i hadn't gone through so much work to set it up for the 5.3, I'd have gone back to a mopar engine. But I already had the trans and the crossmember built and a new driveshaft made so I just went to a 350 crate motor.  Lots of years and money. I had a 51 Plymouth that I put a 318 and AX-15 5 speed in, I had it done over one winter for a minimal investment.  Big $$ lesson learned. 

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I put a 1959 283 Corvette  motor and 350 Trans, in my 1946 Plymouth Coupe and did not have to do any thing to firewall and have a 1978 rear steer Mustang 2 rack and pinon,Now when you get to the inside floor hump that's when the fab, work starts and lots of it and i bought a motor mount and trans, mount and bolt in floor to work with small block Chevy from Butches Cool Stuff and should have just let the money blow in the air,would have saved  $100s by going to scarp yard and cut a  floor hump from junk car would have been faster and not one thing fit like they say,And i end up hiring a friend help that is a master car builder and has had lots of cars he built from ground up in hot rod magazines so good luck.

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