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Magnum 5.2 MPFI with 518/46re swap in 1968 Dodge Coronet Wagon


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7:30 PM
Feb 1, 2013
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Fort Worth, TX
I brought up the swap in another thread but figured there was enough information to create a thread just about the swap.

Here is all the info I have found so far on a magnum engine swap using the 518/46re transmission:

First of all, what I plan to purchase for this swap is a 1995 318, 5.2 L, mpfi engine with the matching 518 transmission. The engine and transmission will be coming out of a daily driver van that was totaled last week and only had 42,000 miles on it. Since it is a 1995 van, the pcm will use older OBDI communication. Also, being a 1995, the 518 transmission will have the 3 pin connector, which means it has over drive and a lock-up converter. If the transmission was older, it would only have a 2 pin connector with over drive only and no lock-up on the converter. If the transmission was newer and from an ODBII vehicle, it would be the computer controlled transmission and require a pcm to shift.

For those only interested in swapping in a 518/46re and not interested in running a factory style pcm and efi, as long as the transmission is 1995 or older, it can be controlled to shift using solenoids and a vacuum switch from PATC. They also have more advanced systems now that are tune-able. Be sure to get the correct flex plate and converter to accommodate the balance style of the engine in the car, and lockup vs. non-lockup depending on year.

For those only interested in swapping in a magnum engine and leaving a 904/727, you must ensure you have the proper converter and flex plate combo to accommodate the externally balanced magnum engine. I will not go over which flex plate or converter to get because every car started with different parts and is vehicle specific.

OBDI vs. OBDII- The earlier system, OBDI, is simpler and works for stock engine applications. For my case, since I am getting the entire engine, transmission, wiring harness, and pcm, it makes sense for me to keep the OBDI to keep cost down for the initial swap. For those looking for run a factory style pcm and want to add performance parts, it is best to buy an OBDII motor, or change the harness and computer to OBDII. The upgrade can be done to an original OBI engine but requires a new harness, pcm, and changing a few sensors. OBDII computer must be flashed before they will work in an older car, OBI computers do not. For those looking for big power, forced induction, or big cams, it is best to ditch the factory pcm and fuel injection and go after market. There are many options here. I plan to leave the engine stock, for now, so I will run the OBDI pcm.

Wiring Harness- The factory harness can be modified to work but is not a job for the average mechanic. A simpler solution is to buy a hot rod style harness that only has a few wires to hook up. I plan to swap in the factory harness with fuse block from the van. I like complicated projects like this and saving money. I probably should just order the hotrod style harness...

Lockup vs non-lockup transmission- obviously lower rpm on the highway is achieved with a lockup converter style 518. There are countless arguments over strength and reliability. I would go with whatever is available and less expensive. For cars with big power, do your research to see if the 518 will last behind your engine. The yoke might need to be changed on the drive shaft to go in the 518.

Magnum vs LA- There is a website called magnum swap .com that talks about the similarities and differences between the two. Find this website for more details. In summary, the magnum engine will bolt in with relatively few modifications and many parts will swap between the two engines. A magnum engine can be disguised as a LA with the right combination of parts. The magnum is a hydraulic roller motor and very inexpensive from junkyards but suffers from a poor factory cylinder head that leads to cracking between the valves. Magnum engines are a great alternative to rebuilding a tired 318 when budget is in mind. I am going the magnum route because I can get a low mileage fuel injected motor with an over drive transmission for less than the cost of adding fuel injection to my stock LA. Kind of a no brainer in my opinion.

5.2 vs 5.9- Personal preference here. I am going with whats available and cheap since I am not after big power.

Fuel delivery- Probably the most complicated part. There are fuel tanks available with in-tank pumps for lots of money. The factory tank can be modified with the right amount of ingenuity. Or a fuel pump can be mounted on the frame rail. Be sure to make sure the pump puts out the right pressure, and/or a filter regulator combo is used. Circulating the fuel with a return keeps the pump cool and increases life span. Do what fits your budget and skill level. I plan to modify the tank to accept the fuel pump from the Vans fuel tank. We will see how this turns out.

Up front fitment issues I know are coming- The drive shaft will need to be cut and the cross-member will need to be custom to accept the 518. The tunnel will probably need massaging to get the drive-line angles correct to prevent vibrations. I may have to go to electric fans to run the magnum serpentine belt accessory drive. To put the motor in the car, I will have to swap to a car LA 360 oil pan and pickup. The 518 needs a big transmission cooler to keep it alive so I plan to bi-pass the factory radiator and use a large aftermarket cooler. There will be more issues and I will keep track of things and share as the swap goes along and after it is complete.

Why not a 5.7 hemi?- Many of you are saying why wouldn't you just do a 5.7 hemi. I even have an late model hemi sitting in my shop that has 20,000 miles on it. It comes down to cost. The wiring harness alone is $1,000 for the hemi swap and is required. Add in radiator, 545rfe transmission, a computer, motor mounts, 6.1 intake, cable operated throttle body, speedo converter, lower pressure power steering pump, oil pan and pickup, and all the mods required to stuff in the motor, it takes a lot of coin to do it right. The average guy spends $4,000-$6,000 in a modern hemi swap. Yes, some of you have done it cheaper, but not every gets an amazing deal or builds everything from scratch. The other big issue is, you have to piece things together from both a truck and a car for a successful swap. So you can't just buy a wrecked car and use all the parts. I wouldn't dare try to put in the NAG1 transmission, can be done, but a lot involved. Lastly, is it really worth the extra effort for a 345 horsepower hemi? The magnum motor is capable of the same output with inexpensive cylinder heads and a new cam for a quarter of the cost. Yes you can mod a hemi but the parts are more expensive than the magnum motor. For me, putting a 5.7 hemi in a b-body is worth the effort in the right car. For a wagon, it makes more sense to do the cheaper magnum motor in my wallets opinion.

The end goal- a reliable engine with fuel injection, an overdrive transmission for highway cruising, relatively clean install on wiring and pcm using the vans harness, re-use factory radiator and column shift linkage, and keep total budget for the swap including engine and transmission under $1,500. So far for the engine, transmission, wiring, pcm, and fuel pump from the van, I will be spending $700 plus the fuel to go get it all. That leaves $800 to finish the swap, wish me luck. I'll post progress as it happens.

If you have any input or if I am totally wrong on something, chime in. I do not claim to know it all. I am merely sharing what I know from personal experience and reading countless articles and threads on the subject.
Yep, I just finished putting a 1999 magnum 5.9 in an 87 dakota. Used the original 904 w/carb instead of efi. Am now putting a 360 in the 67 belvedere with a 95 4 speed w/lockup. I am going to use the solenoids to operate the mechanisms. After getting the whole thing working, there is a new paint job and efi. I plan to make this car a daily, go anywhere driver. A/C and overdrive should be good, eh?
I ordered a factory service manual from ebay for $15 shipped for 1995 Dodge Van. It will have all the wiring and connector pin-outs I will need to modify the original harness. The engine is in the shop. I picked it all up Saturday morning. The guy told me I could grab whatever I wanted off the van for $700. He had already pulled everything but the engine bay wiring harness. Man was I lucky. Here is what I got:

motor and transmission complete with accessories
engine harness
engine bay harness with power distribution center and fuse block
bulk head connectors, firewall, both sides
pcm, body control/air bag module, and abs module
battery cables
drive-shaft, for yoke
a/c lines
power steering lines
catalytic converter, y pipe, and 02 sensor
fuel tank with in-tank pump and pressure regulator

I was able to verify the mileage as well. A few things I need to look for that are not compatible from the van:

car oil dip stick
car transmission dip stick
air cleaner
oil filler cap for valve cover
big block 727 column shift transmission side bracket, cross-bar, and transmission gear selector lever for correct ratio
la 360 oil pan and pickup

Some other parts will need to be swapped from the la 318 in the car. I will put together a complete parts list with prices once I get everything ordered. I will also put together a list of what I pulled off the la 318 to bolt on the magnum 318. There will also be a discussion on hooking up shift linkage once I get there and verify what I think I will need to make it all work. I'm excited and can't wait to get started. It does feel a bit odd tearing apart a running driving car. But it will definitely be worth it.

photo 1.jpgphoto 2.jpgView attachment 227125View attachment 227123View attachment 227124
Did you know the 518 will bolt up to the Hemi?
Did you know the 518 will bolt up to the Hemi?

I did. I suppose then you would control over-drive and lock-up with pressure solenoids and a vacuum switch since the hemi's pcm won't? I am saving my hemi for another car with less doors and more reason to go fast, my 70 cuda, but if I decide to keep it automatic, I will definitely be looking for another 518. As cool as it would be to put the hemi in the wagon, the reasonable side of me is keeping me from spending big money on a car that will never be worth big money.
Let's come to terms with this early on. My initial budget was a bit optimistic. The fuel system is going to eat up most of the remaining budget if I truly want to do this right. I could probably re-use as much as possible and stay close to budget and just do the swap, but that's just not me. While the engine is out I might as well paint the engine bay. While I have the k-member dropped, might as well disassemble, clean, blast, paint, and swap bushings and ball joints. Might as well redo the brakes while I'm there. Might as well change the seals in the steering box while its out. You can all see how this is going to snowball out of control.

So from now on there will be two budgets. One will only count what was necessary to successfully complete the engine/transmission swap. The other budget will include all the new parts and restoration work that was not necessary to get the car going, but I just can't help but do while I'm there.

Lesson 1, it makes more sense to buy a new tank to cut and weld on when they are only $140. I'm not sure it's worth the risk to try and clean the original and risk fuel vapors exploding when cutting/welding. 1968 B-body wagons use the same fuel tank as 1966-1967 B-body sedans and hardtops. Good to know since it's not listed in any online catalogs.

I thought about using the fuel pump and regulator from the van. Then I saw this module with a sump. There is also a more expensive aeromotive version they call phantom 200. It would require an adjustable externally mounted fuel pressure regulator. There are no in-tank regulators that I can find that have low enough fuel pressure. The early OBDI fuel injected motors require in the neighborhood of 40 psi and are return-less systems. I am still brainstorming on the fuel system so we will see where I end up.

Apologies if this bumps the thread up - but are there any updates to this particular project?

I'm particularly curious as to the fit of the 46RE under the '68-70 B-body floorpans, as I plan to do a similar swap (and have already placed a pre-order for Tanks Inc.'s EFI-ready, baffled Coronet/Satellite tank; company says they should be shipping approximately 3 months from now), but had not considered swapping my A904. Most of my research has been at FABO, where trans tunnel clearance presents problems with the later transmissions - I hadn't stopped to consider the additional room provided by the B-body platform until this minute.

Any thoughts on a crossmember, or would that be strictly custom-fab at this point?

Unfortunately, when the bottom fell out on oil prices, I had a feeling layoff's would be unavoidable. Instead of being caught off guard, I put all of my projects up for sale to pad my savings. I wanted to be sure I could pay all my bills and mortgage for at least a year with savings. The wagon and engine sold almost immediately, but didn't loose any money. The car went to a friend who is going a different route, 440/727. I really really wanted to keep this one. I'm thinking I may be able to get it back in the future.

It has been pretty scary. Luckily, I made it through the first two rounds of layoffs and still have a job. I probably won't play around again until prices come back up to a level where shale formations are profitable...I may be waiting a while.

To answer the questions, from what I have read, there are only minor clearance issues that can usually be solved with a hammer and dolly. For the crossmember, I could not find anyone that sells one already made. There was a shop willing to make me one using a template from another swap they had done. In order to get the drive-line angles correct in order to avoid vibrations, I would definitely suggest custom fab.
Since that is a 95 trans, it should be an RH not RE. If its an RH, it can be controlled with simple switches for the od/lockup. RE needs the PCM to operate it. I did a 5.2 conversion on my father in laws 83 CJ7 12+ years ago and when it was said and done, it was pretty easy with the integration of electrical between old and new. At first it was like OMG. I got blowups of the wiring between the CJ and a 93 Grand Cherokee to mezmerise myself with squiggly lines to figure it out. No one at the time was doing magnum swaps so I had to figure it out on my own with a little guidance from one of the dealer master techs I worked with. Also on the trans, if its an RH, they can be shift kitted easily like a 727. Have fun and I hope the economy improves for you.