72 280SEL FI / Carb swap

[sdruger44]

I've got a 1972 280sel 4.5. I was wondering if it would be possible to change out the fuel injection system for a carb setup. I'd like to know if it's:

A) Possible
B) Practical
C)Are the parts available

[alabbasi]

I discussed the same thing with my Mechanic when my 280SEL 4.5 had FI issues. The Mechanic said that it's not likely.

Are you having FI issues?

[sdruger44]

Yes, I'm having MAJOR FI issues. The car has been off the road since 1994. Cosmetically it's in PRISTINE condition, with 14K original and documented miles. I got it at the awesome price of $0 Mechanically it's great also, except for the FI. First of all, mice and rats made themselves a wonderful home in the air cleaner housing, but in the process of living there they also managed to chew up all the rubber and electrical under the hood. So far I've got it straightened out. Today I pulled the injectors and had a hard time since they were rusted in place to the manifold. The rubber o rings were gone. I've basically given the car a good going over... as in fluids, plugs, wires, cap rotor, etc... but it runs ROUGH AND RICH. I've tried all the suggestions I read on here, but it hasn't helped. I'm beginning to think it's hopeless. I don't mind putting money into the car, but it's the time that I'm short on. I'm a 23y/o student with 3 too many cars already!

Also, is there a shop manual available?? So far I've been working from info provided on this board, but I think if I'm going to do this right, I'll need a manual

[alabbasi]

I know how much a pain it can be to tune these cars to make them run right. We have a lot of very knowledgable people here who know these cars. Mine ran super rich as a result of a problem computer. I spent a lot of money with a lot of Mechanics trying to determine that. I know make sure I grab every computer in the junk yard that I come by.

The computer and map sensor can be adjusted to make the car run richer or leaner. Do you have any details on how it runs now?

Manual can be bought on CD at the Mercedes Benz classic website for around $20.

[sdruger44]

I know it runs very rich. I can smell pure gasoline in the exhaust. I'm picking up new injectors tomorrow. and then taking the car to a friend's shop. He's got a smog machine, so I'll be able to tell exactly what's coming out of the tailpipe. This car is just WAY too nice to let it sit. If the injectors don't solve the problem, what do you think I should do next? I've alowed myself a 400 / 4000 budget for this car ( 400 hours and $4000 ) Other than runnig rich, it's an amazing car. If I get it running right it will become my daily driver instead of the S600

BTW.. can you provide me with a link to the Mercedes Benz classic website.

[alabbasi]

This is what we did in our diagnosis.
1. Drained the oil and replaced with new oil, it's always going to run like crap if there is gas in the oil so expect to do a lot of this during your investigations.
2. Adjust the map sensor
3. Adjust the computer (if you have a co2 sensor, you may want to try doing the adjustment on the co2 sensor)
4. Replace the computer and map sensor (separately) with another set (preferably known good ones) to determine if there is a problem with these items.
5. Check the trigger points

Injectors are high dollar items on these cars, I would drain the oil and run the car with fresh oil to see how it runs first. You should see a huge improvement. Then see what it's doing at that point.

here is a link to the classic center http://www.mbusa.com/heritage/index.do Just go to the technical literature section in the classic center pull down and then select your car from the pull down list on the next page.

Here is a link on a trouble shooting guide: http://w108.org/forum/viewtopic.php?t=10

If you were in Atlanta, I would send you to the Mechanic who sorted mine out. I'm certain your having the same issues that I had and I feel your pain.

[Mark DiSilvestro]

A) Possible - yes
B) Practical - maybe, depends on your mechanical skills.
C) Are the parts availible - Carbs are availible but you'll need to fabricate any adapters and linkages needed to install one, as I'm not aware of any factory carbureted version of your Mercedes V8.

A few years ago, there was a 450SLC on eBay with a carb conversion. It looked like it had a Rochester Quadrajet mounted on the intake manifold but the photo wasn't too sharp. The car was (as usuall) across the country, so there was no opportunity for me to go look at it in person and no idea how well it worked.

Happy Motoring, Mark