Last updated 11/30/02
Thanks for checking out the Mercedes-Benz 5.0 Swap page. This is a documentation of the swap I performed on a 1980 Mercedes Benz 450SL. The car belongs to my wife's uncle, who was seeking more performance out of the car. At the time, he had already paid a service to do some minor engine mods on the stock 4.5l engine, including head porting & milling, and a free-flowing exhaust system.

I suggested an engine swap, since he was unhappy with the resulting performance, and there are very limited resources for aftermarket Mercedes performance goodies.

My first idea was swapping in a Buick Turbo v6 from a Grand National, but physical restrictions prevented that, mainly because of the rear-sump pan configuration. Same problem with small-block Chevrolets, plus the distributor-to-firewall interference.

So the small-block Ford became the natural choice. Size, layout, and aftermarket availability all added up to what I thought was going to be a fairly straightforward swap...BOY WAS I WRONG!!!!!

First of all, the crossmember had to be cut (notched) for oilpan clearance. This required cutting out the top half of the crossmember down to the seam where it it welded to the lower half, then welding in some 3/16" steel plate to box it all back in. Even still, I felt the crossmember would be weakened by this, so I also welded a piece of 1/4" steel to the underside of the crossmember for reinforcement.

Even with that done, I also had to modify the Milodon oilpan I used. This was the 7-quart front sump pan for older Ford applications. To get the engine back towards the firewall (for good weight transfer and also radiator fan clearance) I had to cut off about two inches of the back of the sump area and box that back in as well. So far no leaks!

Then the idler arm hit the starter, so that had to be moved over to the outside (toward the passenger side framerail) by cutting about 2" out of the tubing that supported it, and I actually used an old socket as an inner tube before I welded it back together. Of course, by doing this, I had to lengthen the center draglink (also by using a ground-down bolt for inner strength, and a piece of steel tubing for outer sleeve). Then the tie rods were adjusted by lengthening the driver's side and shortening the pass side. Believe it or not, geometry still remains intact, and it turns on a dime either direction. I also had to grind off a small area of the engine block where it came in contact with the steering gearbox. As it is now, there is only about 1/8" or so of clearance, but with the more solid urethane mounts I used, there is no contact anymore.

One problem I encountered later was when I had it aligned. Perhaps when I boxed the crossmember in, I should have spread the front end apart before welding, as the alignment shop was not able to achieve the correct caster/camber. The only way they were able to get enough negative caster (top of the centerline of the spindle axis tilted to the rear, or bottom of the centerline to the front) was by sacrificing some camber, also pulling it in negative (tops of the wheels tilted inward slightly, I think about 1 degree more than they should). This is still OK, actually, sice it's better to have more negative camber than positive).

Exhaust: I initially purchased a set of the Motorsport shorty headers, which fits perfectly on the pass side, but there was no way on the drivers side. So I used the other shorty header as a starting point, basically keeping only the flange and chopping off everything but the stubs, then welding a piece of 2-1/4" mandrel-bent tubing as a "log" style manifold. This was very painstaking, and is not the greatest design for flow, but is about the only thing that would fit. Even then, I had to dimple the underside of the last primary tube near the firewall to clear the steering box adjusting nut.

I used the Ford AOD trans that came with the donor car (1989 Mustang), after having it rebuilt by a local performance shop. This is a four-speed auto trans with overdrive. Fortunately, all I had to do was slot the holes in the factory trans support to make it fit. Then I modified the stock shifter to accept a Ford-style shifter cable. More on this later.

The stock driveline was retained with carrier bearing (not enough room for a real driveshaft),and of course it had to be shortened. We shortened the front piece, and had it fitted with the Ford yoke for the trans. The big rubber biscuit was retaied at the rear diff, but clearance was so tight getting it in place, I had to cut some of the pinion snub of to get the thing in. Remember, the driveshaft length needs to be exact, since the diferential doesn't move up and down (in other words, the front yoke isn't sliding in and out).

More info later on the 240 D differential I used with 3.69 gears.

This has been by far the most entailed automotive project I've ever indulged in...live and learn! I've had the car in my posession for almost TWO years...obviously I don't spend every day on it, in fact there have been many long dry spells where I didn't even want to look at it. But, it is nearly finished.

Despite all the pain and suffering, the car has been running since March 2002. Since these photos were taken, I had hoses made up and got the a/c system charged and working, which was actually about the easiest job on the car! One hose to the condenser, and one to the existing evaporator hose.  Anyway, enjoy the
photos and commentary, and sign the guestbook if you want...by the way, DON'T TRY THIS AT HOME.
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