1949 Plymouth Coupe 3.6 VVT Powertrain Swap

[Plymouthy Adams]

while not the 3.6 I have already done this with the 3.7.....nothing crazy about it....

[Mopar 49]

While I'm tearing apart the rear end of the car. Does anyone know of a company who makes fuel injected fuel tanks for the 49?

I have to swap the fuel pump from the Chrysler. The tank is molded up into the body of the car and tucked up above the drive line. It can be dropped but is nothing like the 49 for configuration and shape. I've seen some of the tanks for the more popular models like the 57 bel air but no luck for the Plymouth.

[Plymouthy Adams]

unfortunately not many companies dedicated to the older mopar and even fewer for retrofit into the older mopar....there are late model fuel tanks within the family of products you can draw from.  Finding a direct bolt in for your proposed upgrade into the original footprint may not be possible...there are some that will be close that you can make do with....that depends on how involved you wish to get with the tank itself.  

[Sniper]

Not a 49. but probably easier to make work. 

 

https://www.tanksinc.com/index.cfm/page/ptype=product/product_id=226/category_id=68/mode=prod/prd226.htm

 

The fill tube is actually a hose in the pic.

[Adam H P15 D30]

On 7/17/2021 at 9:47 AM, Mopar 49 said:

With a little more looking I found a half dozen explorers at pick n pull if they have the rear end in them they would work, they came with factory disc brakes just before they changed to a IRS. They all would have a 3.73 a couple of the older ones might even have a 3.55 and drum brakes. It looks like the sport had the 4.10. 

I found a sport axle out of state with a 4.10 online with factory discs. If I have it shipped to my house it's almost $300 shipping if I call the local auto recycler on Monday I should be able to cut the price down a lot by shipping to the LKQ distribution center about 5 min from my house.

I would love to get an old rear end under the car but most of the cross over vehicles tend to go for more than my Plymouth and the parts are 3-4 times the cost for a rusty pumpkin with tubes attached.

The first stage of the build will be a little more than 300 HP after the motor is running and tuned and the vehicle is able to drive.

The second stage will be to add the supercharger kit to boost to 430-450HP. I'll keep my fingers crossed that the 8.8 can handle it.

Part of my build idea is to run parts that I can easily get, the Chrysler 3.6 is super plentiful as is an explorer rear.

I will need to sell the parts I pull to help offset the build cost. Someone who isn't running a hotrod will probably appreciate finding them.

I will also be putting some progress pics and design ideas in case someone else is crazy enough to do this.

 

 

An 8.8 will handle anything that little V6 will throw at it, no worries there. The Mustang crowd throws much more than that at it. 
 

I retrofitted a Tanks gas tank for a 46-48 Ford in my 47. It has provisions for an in tank fuel pump. 
 

[Mopar 49]

I think the 8.8 explorer rear will work and look to be getting one coming next week. I looked at a lot of fuel tank pics and dimensions and looks like a 56 Chevrolet fuel injection tank is a close fit. It was my pick a few weeks ago and think I’m going to order one. A 74 challenger tank was also close but hung down a lot more. I pulled the cars next to each other and jacked the Plymouth up and Kroil’d the rear driveline and suspension bolts. The driveline looks like it got some work in the past but the leaf springs are rusty and crusty. They have the rubbery Grey covers on  them. So my question is, is it worth it to redo the springs? I don’t know if I’m ready to retire them but I’m thinking  rebush, new bolts, clean up ect. There is nothing sexy about springs but they are pretty easy to drop when there’s no rear end.
I don’t think I’m crazy fixing up this car my friends at work do. My wife’s grandpa had a Plymouth sedan and she likes this car and would like to see it as retro modern everyday driver. I’m thinking pro street rat rod so I’m not afraid of mixed parts to get a good result.

This car was owned by a vet buddy of mine that didn’t have the time to improve it. He loves Fords & Datsun Z cars.

I guess there are not a lot of bolt on fixes for the 49 and they don’t fetch a ton of money. 

[Adam H P15 D30]

Check Posies for replacement springs.  Either way you will have to come up with some traction device with the narrow leaf springs to avoid wheel hop.  

[Mopar 49]

A good point on the narrow leaf springs. They are pretty flimsy. I was thinking of mounting the Ford rear axle on the factory springs and swapping to a 4 link later. 
I hate to do the work twice but want to get to testing the motor in the car before the weather changes.

 

 

 

[Bbdakota]

I'm very interested in watching this thread..... cause I've thought if swapping the 3.6 and 8 speed myself. One thing I've run into with Chrysler products is the wheel speed sensors are monitored by the computers and on the NAG1, are used for shifting. I'm not sure about the 8 speed but I'd lay money on the fact you'll need to provide rear speed signals for the computer to allow proper shifts of the transmission. Something to keep in mind..... you may be able to put a tone ring on the driveshaft and mount the wheel speed sensors to read the tone ring. 

Edited July 20, 2021 by Bbdakota

[Bbdakota]

Here's a pic if the tone ring on my NAG1

[Adam H P15 D30]

Another good reason t go to the 8.8, it has a speed sensor in the top of the housing.  I use it for my electric speedometer.

[Sniper]

You know there is a screw on adapter used in 80's Dodge trucks that will provide an electric speedometer signal and ought to be useable in our applications.  Easier than a rear ale swap if ALL you need is a speedometer signal. 

 

STANDARD MOTOR PRODUCTS SC108 or similar.  S-727 is the matching electrical connector.

[Mopar 49]

I have the 8.8 coming in about a week, the wrecking yard guy asked are you buying it for a hot rod or ranger swap? Said he had sold 15 of the explorer rear ends in the last couple of months for both. It would explain why I had to get mine from out of town.

I pulled the rear and need to do some cleaning. I was going to leave the springs and mount the axle back to get it moveable. Then I had a few friends suggest I would be happier with the result of doing a 4 link.

Now I will put the 4 link with coils in and get rid of the rest. I think I will be happier with the end result, I just have to add some more of my sadly lacking free time to get the angles measured out and welded in.

[Sniper]

Straight four link or a triangulated setup?

[Mopar 49]

Triangulated four link with coil overs. Any suggestions? Figured if I matched the existing axle location and height and lined up the original motor and driveshaft I should be good to go. I've had other people tell me I should have the new motor and trans in before welding the axle.

 

[Sniper]

I think they might be referring to having the as driven weight there to set the angles up properly.  But if it's adjustable I don't think it would be a big issue.

 

Not a big fan of triangulated four links, but my experience has been with OEM ones that use large and soft bushings to allow for compliance.  On my Mustang I ended up going with a watts link to control side to side sway of the axle, this was after upgrading to poly bushings in the arms.

 

Might keep a watts or panhard setup in mind if you think the rear is too wiggly later on.

 

 

[Mopar 49]

Got my rear end from Texas and started soda blasting the frame clean to attach the 4 link suspension. I had an error with the ABS module in the donor car that would not let me read the PCM module. I disconnected the ABS was able to read the PCM using HP tuners ODB scan tool and sent the PCM to get unlocked this week. The car had a lot of surface rust on the frame that comes off pretty quickly with the soda blaster. 

[Mopar 49]

I have been back and forth on doing an IFS on this car and was thinking of keeping the front suspension and rebuilding it, but perhaps doing a Vega steering box.

It looks like the Vega steering will mount to the frame a bit lower than the Plymouth steering box and that should give me a little more room for the AC pump on the motor side. There are options for manual and power for the Vega type. So has anyone done a Vega box in a Plymouth and could you recommend it if you have.

 

 

[kencombs]

On the Vega box:  I haven't and wouldn't as it was intended for a much lighter car.   they are used a lot in the hot rod world, but mostly on light weight roadsters.

 

 

[Mopar 49]

Had some time this weekend to tear down the front end of the car to get ready to remove the motor.

I also pulled most of the interior out and ordered a couple of rocker repair panels to address the rust at the rockers, since I will have the welder out anyways.

Sorry about the sideways pic it's upright on my phone and computer.

 

[Adam H P15 D30]

On 8/7/2021 at 11:35 AM, Mopar 49 said:

I have been back and forth on doing an IFS on this car and was thinking of keeping the front suspension and rebuilding it, but perhaps doing a Vega steering box.

It looks like the Vega steering will mount to the frame a bit lower than the Plymouth steering box and that should give me a little more room for the AC pump on the motor side. There are options for manual and power for the Vega type. So has anyone done a Vega box in a Plymouth and could you recommend it if you have.

 

 

A long time ago, on this forum, someone adapted a ?Mustang? steering box.  I believe the Mopar pitman arm fit as well.  

[hkestes41]

On 8/7/2021 at 3:35 PM, kencombs said:

On the Vega box:  I haven't and wouldn't as it was intended for a much lighter car.   they are used a lot in the hot rod world, but mostly on light weight roadsters.

 

 

I agree with Ken. I used a new Vega box on my 37 Plymouth coupe to replace an old Flaming River box that was worn out after about 20 years of use. The Vega box from Speedway lasted all of about 6 months. 

 

Went to a Borgeson Universal 920011 - Borgeson Universal Saginaw 525 Manual Steering Box that has now been on for over a year with absolutely zero issues. It has the same mounting pattern as the Vega box so bolted right to the mount. 

[Mopar 49]

Thanks for the info on the steering box I don't think I will put the Vega box in. It does sound like you get what you pay for Speedway vs Flaming river. 

I was able to get the rear axle on a rolling jig to get it under the car and mark out the rear suspension. 

[Mopar 49]

I have the front end of the 300 partially pulled and am tracing out the wiring harness.

I plan to reuse the Chrysler wiring harness in the Plymouth since the 70 year old wiring is pretty much done for.

I am hoping to get the motor/transmission pulled together in the next couple of weeks. I would rather pick and slide out the entire assembly than break the motor and trans apart and put back together.

I plan on reusing the transmission mounts from the 300. I might have to fab a couple of extensions or use the existing mounts as a template for new mounts.

Once I have the motor/trans hanging in the engine bay of the Plymouth I can see where the engine mounts will line up.

I was going with the slight offset idea for the mounts to allow the steering box to stay and rebuild the front steering. 

I may still go with a IFS, it will take longer to get the motor in but will free up some space at the front of the frame and add power steering to the car.

 

 

[Sniper]

Following this with great interest