M110 carburetor replacement?

[Hit Man X]

Like most, I have the troublesome Solex 4A1 on my 1979 280S.  The car will not idle unless the foot is on the throttle.  Everything I've read is that this carburetor is junk and I'm ready to replace it so I can enjoy the vehicle like it was intended (sadly mine is not fuel injected). 

I have a 4360 Holley that I rebuilt already that's going to be installed.  My questions are regarding the linkage, what is everyone doing for this?  Are there any pictures? 

I do not expect the vehicle to be a race car, I just want good reliability with good throttle response as this is mainly a city vehicle. 

Thanks

[alabbasi]

Similar threads have been discussed on the mercedesshop forum about the 280 and the 280C models. It may be worth a look there.

All the best

Al

[oscar]

Like most, I have the troublesome Solex 4A1 on my 1979 280S. 

Well that just answered my question I asked in your other thread.  Here's one of my previous answers only a few days ago.  I'll get pictures of mine soon.


The two recommended conversions I've heard about on the forum is either a Holley 4160 list#8007 390cfm or a Weber 38DGAS. 

I've got a 280S with that Holley carb which was already fitted before I bought it.   The engine it's fitted to isn't in the best of shape and needs reconditioning with one cylinder with little compression so I haven't been able to test the holley properly but it runs and I drove the car round a few times.

[Hit Man X]

I just couldn't come up with much in the vintage forum on MS, almost everyone seems to have a 280 SE/L or if they did swap the 4bbl the car is long gone  =-(

[Hit Man X]

Like most, I have the troublesome Solex 4A1 on my 1979 280S. 

Well that just answered my question I asked in your other thread.  Here's one of my previous answers only a few days ago.  I'll get pictures of mine soon.


The two recommended conversions I've heard about on the forum is either a Holley 4160 list#8007 390cfm or a Weber 38DGAS. 

I've got a 280S with that Holley carb which was already fitted before I bought it.   The engine it's fitted to isn't in the best of shape and needs reconditioning with one cylinder with little compression so I haven't been able to test the holley properly but it runs and I drove the car round a few times.

Cool!  If you could gather some pictures, that would be fantastic!

[oscar]

I was going to post the solex as well but you know what that looks like and can compare.  There's just that one extra bent hex rod that's not standard but there's also the base plate that's different and of course the electric choke needs wiring up and fuel lines changed.  just let me know if you need anymore pics and of what.  You'll find yourself omitting things like the wires to the fuel cutoff solenoids.

[Hit Man X]

Hmmm, seems simple enough! 

[Hit Man X]

I found my 4360 today in a box in the garage.  I may try to install this weekend 

[Hit Man X]

No luck, been busy workin on the Volvo.  I will get it on sometime guys  LOL

[Niclas]

Like most, I have the troublesome Solex 4A1 on my 1979 280S.  The car will not idle unless the foot is on the throttle.  Everything I've read is that this carburetor is junk and I'm ready to replace it so I can enjoy the vehicle like it was intended (sadly mine is not fuel injected). 

I have a 4360 Holley that I rebuilt already that's going to be installed.  My questions are regarding the linkage, what is everyone doing for this?  Are there any pictures? 

I do not expect the vehicle to be a race car, I just want good reliability with good throttle response as this is mainly a city vehicle. 

Thanks

Ohh no, don't do it. Show those German engineers some respect!
Your Merc will never love you if you do that conversion.

I've had three M110 fitted cars, one -73 280S, One 76 280S and one -81 280SE(W126). Both the carburettor fitted ones run fine with a low fuel consumption. The -73 one used 11 liters per 100km and the -76 one 12 liters due to the lower compression ratio.
(The fuel injected one used 12 liters)

The only problem I had was that on the -73 one there was a vacum controlled butterfly valve that was stuck in closed position. This coused the car to not get full throttle.
This foult was easily helped with some oil.

/Niclas

[another sad 280s]

i have always been surprised that nobody seems to consider it ever worthwhile trying to persist with the solex. there must be ways to overcome it's faults. personally i would much rather throw money at the solex, even though it is french, than to put on anything else which would have to be sacrilege

[oscar]

Hey Hitman, I'm gonna change my tune and agree with the last two after doing recent work on my Solex.  Besides, I did some searching on the 4360 and apart from being NLA from Holley, it's too big a carburettor at 450CFM.  The 280 would prefer a 350CFM two barrel if going with Holley.  As I said before, I've got a 4BBL 4160 390CFM on the spare 280 which will be going on my other 280S but it's a racecar.  Fuel economy wont be an issue. 

But, as stubborn as I am I've been determined to fiddle with the Solex over the past week or so until it works properly.  My only issue remaining is the dashpot connected to the secondaries.  Its diaphragm is perforated and the secondaries' air valve opens before the bypass for stage two gets a chance to operate.  So there's a lag between the power increase when transitioning to stage two.  Not real good for racing.  But once this dashpot issue is sorted, my solex will be fine.  There's been other issues with mine but they've all been sorted in the past few days.

Is it just the idle that's playing up with yours?  Three things I can think of that are causing no idle without the accelerator being depressed.

1 - Screw in the idle mixture screws then screw them out about 2 turns.  They could be screwed in too far or clogged up.  Might be worth screwing them out further by another 2-3 turns to see if that helps.

2 - If that doesn't work check the idle cut off solenoids.  Either power's not getting to them or they're both cactus.  Best way to test would be to have someone switch the ignition on and off to II whilst you hold each of them in turn and feel a click.  If they click it means they're most likely energized and open and ok.  I'd be keen to override these things maybe by just putting in a short screw or bolt in their places so the gap where the fuel is usually cut off isn't obstructed but I've got no reason to do this yet. 

3 - Lastly, the idle speed air jet might be clogged which results in a restriction of fuel. 

Any of those three can be overcome by pressing the accelerator so the idle circuit is bypassed but my advice would be to ultimately take the solex off then pull the top half off.  Give the whole thing a good dousing with a carb cleaner making sure you spray out all the air and fuel jets.  Take out the idle mixture screws and spray in there.  Take out the fuel filter from the inlet and clean that too.  Check float level and adjust so that the float wont hit the top half of the carb.  Go to the library first and copy then print the relevant pages and read up.  (BTW I reused all the gaskets when reassembling).

Not really trying to dissuade you doing a conversion, as I said I'm going to do one too but although the solex has some stupid design features IMO making it over complicated and flimsy in some of its construction but I've found it pretty simple to fault find so far and am having good results.  Might as well be sure the Solex is cactus before you move to a Holley or similar because believe me, my Solex'd 280S is surprisingly fast off the line, faster than my d-jet 350se and does cruise comfortably.  It's worthy of some further investigation (which wont cost anything bar a can of carb cleaner).
Now for the links. 

Here's the library stuff.  From the link below "07.2 Carburettor, fuel pump, throttle linkage" on the left, then the job numbers are on the right.  Click the lower right hand side "More" arrow to go through the 14 pages of separate jobs.  Each time you click on a job a new PDF will open in a new window. Library Link

And here's my latest stuff about my solex Link

Also google "Solex 4A1" and there'll be some BMW forums "E21" or something or other with questions about the solex but more importantly, links to some teardown/rebuilds.  Great advice there in those teardowns.

[Niclas]

Slightly off topic, but my friend went to a coarse in cumbustion technic. The professor told him a whole lot of things, but the most surprising was that there is still today no fuel injection system that provides an as even mixture of fuel/air as a good carburetor.

There is still of course the problem that you need to have a venturi throat on the carburetor resricting the airflow at full throttle.

/Niclas