I just picked up my second 1973 450SL. It has 247K miles on it. My question is: Can I swap out the old 1973 450 engine for a 1988 560SL engine? There is a guy in the town nearby that has a 1988 560. I think the distributer for the 560 can still be used if the mechanical advance is the same? I think I would have a problem though if the old fuel injection intake manifold didn't fit the new 560 intake ports. But if the intake did fit the 560, how would I adjust the air fuel mixture for the added displacement, or would I need to? I don't want to use the 560 computer and wiring harness. I would like to use the old one.

A daunting task.

The following thoughts only scratch the surface

1) Different ignition systems all together

2) Different fuel injection systems K-Jetronic [mechanical] versus KE-Jetronic [electronic]

3) Transmission and engine together (speedometer drive modification may be required)

4) Exhaust system from the 560 may be serve you better

5) If installing all the 560 electronic controls wiring!!!

It can be done, how bad do you want it?

Then again you could just setup the engine as if it were the 450 and see what happens.

from experience but from personal experience i can make a few comments.

if the intakes interchange, and i think they may, and if your 450 is in good operating condition, then swapping all the engine fuel and electrical parts over to the 560 engine sounds like a good plan. i have no personal knowledge if this is possible or not. if you could do that it would solve all sorts of interface problems with engine/chassis wiring harness issues, etc.

the exhaust surely could be used from the 560.

i dont think that you woiuld have to worry about mixture etc. the fuel system i beleive senses air flow and would provide the proper mixture regardless of the size of the engine pulling air through it. the size of the intake on the 450 system may simply limit the 560 to the power of the 450 or similar.

just a few thoughts.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

The 73 450 should be an EFI car. The EFI system is a speed density setup so it doesn't measure airflow. It measures intake vacuum, engine speed, and somewhat archaicly throttle position. It will not run properly on the larger engine without corresponding adjustmants to either injector size or fuel pressure. That being said the EFI on the 73's was the WORST injection system ever put on a car. The parts are prehistoric and terribly expensive. To be generous I will say that the 73 EFI when working at 100% of it's design is marginal at best. This was the first serious attempt to make an EFI car. To swap it onto a 560 would be like replacing your pentium processor with one from a commodore. If you are seriously considering modifying your 73 from stock the first thing to go should be your entire fuel injection system.
By the time you convert your SL to another fuel system along with another engine (and tranny) you will realize that you would have been much happier simply buying a decent used 560SL. Although they are the same body, the 560 is superior in almost every way to your 450.

I stand corrected on the fuel system, it is D-jetronic.


Thanks Dux, what year did MB install K-Jetronic on their vehicles?