Solex 4A1, 1975

[Takernz_30]

Sev,

my email is roldan_q@yahoo.com, i would like ask about your Solex

[wolf_walker]

Originally Posted by Sev

if anyone wants a practise solex, i have a couple laying around, pm me

Yes, Target Practice. With a .308@300yrds would be enjoyable.

My last straw was when the pressed in float
seat came out in a parking lot after a nice dinner with my woman
a few months ago.

[Bill Adkins]

Simple fix, press the seat back into the base and stake it with a sharp punch around the base. Did many that way
Bill

[gerardoparedes]

I spent good money and a good mechanic on the Solex, a master technician, used to work for the MB dealer and went independant, but now i need a fuel pump, because i think is leaking, oil is very thin and i get around 8 mpg. Does anyone have a good plunger type mechanical fuel pump for the M110.922.

I still have on my plans to megasquirt it using a TBI throttle body, just havent got the money yet, also the head need some work since is burning some oil due to worn valve guides, i believe because the fuel pump issue has been running for so long, i have only put 6000 km into the car since buying it (its an euro), it even had some mice living on the engine compartment.

Car also has a leak on the rear main seal, i believe you need to remove the engine to solve this uh? I am just waiting because i have to repair this leaking seal i as well want to do some job on the clutch.

[280EZRider]

Originally Posted by Jayeff

For all U vintage freaks. Yeah, we're out there.

Solex 4A1 for the M110

The infamous Solex 4A1 has been the bane of MB owners. But when properly set up and working as it designed to, it gives flawless performance with the 110 engine.

The 4A1 air horn warps in time. Once this happens vacuum leaks develop and the engine stumbles on accelaration, won't idle, hard starts when cold, and becomes impossible to drive if things get bad enough.

The usual practice is to tighten everything down as much as possible. This always distorts the castings even more. The next step is to tweak all the visible adjustments, then go into the capped adjustments and tweak those. By this time things are a hopeless mess.

A rebuild kit is not the answer. Both OEM and replacement gaskets are made of a thin, hard, incompressible material that will not seal the gap.

All kinds of fixes have been devised, like putting the air horn and bowl into an oven fastened to a flat plate, dressing the mating surfaces on a belt sander, filing them etc.

My solution, which is simple, very inexpensive, and very effective is to make new gaskets out of 3 3/2" gasket paper. The gasket between the air horn and the float body is the most complicated. All the holes and their locations have to be an exact duplicate of the original. The others are very straightforward.

To do this I took a new gasket, put it in a desktop copier, and copied its exact shape to gasket paper that I ran through the manual feed tray just like an 8 ½ x 11 sheet of copy paper. Some copiers don't make a dimensionally precise image, so I made sure the copy was accurate by measuring all locations against the original.

Then I made small hole cutters out of tubing, as required, and used a fresh exacto knife and a metal straight edge, etc. It takes about two hours to cut it out. Soft music in the background seemed to help. The first time tried it I wasn't happy with the result so I made a much better one the following day. I use a softer gasket paper about four times thicker than the original (not cork).

When you assemble the carbureter, wrist tight is enough. Getting all the adjustments right can be time consuming, especially when someone has changed all the capped adjustments, which were never meant to be adjusted.

I made a chart of my beginning adustments with parallel columns showing the changes I made as I test drove the car. It was trial and error, as I had no idea which way to go.
Pretty soon I got a feel for it and things kept improving. Once I got the car running fairly well it was a matter of a tweak here and a tweak there. It took about two months to really fine tune it.

I have no problems with stumbling in hot weather, cold start is immediate, there is no lag in accelaration with your foot to the floor, and idle is dead steady with no burbles. I haven't had to make one change in many years. Now and then I will check to make sure the assembly screws haven't loosened up, but I never have to tighten them more than a fraction of a turn.

Everything else has to be right – the spritzer diaphragm, the dashpots, the float level, the float chamber vent diaphragm (important), the TN choke, if it has one. The instructions tell you how. All the smog control plumbing has to be vacuum tight. Mercedes is usually pretty good on that. Go by the book. None of this is hard to do, it just takes patience.

So don't give up on the Solex 4A1.

Jayeff

'73 280, '75 280, 86 560 SEC. '58 Jag XK-150 DHC, '54 Jag XK-120 Roadster, '98 Chevy Lumina, '79 Dodge D-100 Pickup, 92 GEO Metro.

Nice tutorial! What you have done can only be done by a real mechanic - not a parts changer.

[Takernz_30]

Jayeff,

Your stuff works great, I use 2 DIY paper gaskets but the thick paper gasket didn't gone thru the printer b/c it was jammed and my big brother did gave me an earful of scoldings. Anyway, I bought new kit from my long-time parts dealer but isn't really complete(missing are diaphragms for choke and accelerator pump,fuel valve, couple of idle mixture screws and in -carb fuel filter), used the new gasket as source pattern and I put the new gasket on top of paper gasket and used a drawing pen and drawn out from new gasket and I used pen cutter to cut the drawn lines w/ assorted tips small tips for cutting small holes and the big ones for larger ones and I carefully cut out the paper gaskets especially the small holes, I spent 2.5 hours w/ Enya playing in my PC, it works for me.

I installed it yesterday and it was working, holding idle when the stick in D but when part throttle, it will hesitate or almost stalling but when I slam the throttle, it was fine, maybe there's a leak somewhere and I'll investigate.

[wolf_walker]

Originally Posted by Bill Adkins

Simple fix, press the seat back into the base and stake it with a sharp punch around the base. Did many that way
Bill

That I did, after saying a lot of bad words about a non-replaceable seat.
Goofy solex.

Anyway, this thread is worth bringing up again for new readers.
And I spent this evening mucking around with my original 4A1
since I'm not driving it daily now, I can play with things more.

[Rick76]

The float valve seat is repairable.

Two repair sizes are available (or used to be).

Repair stage 1 part number 000 071 01 94 identified by 1 groove machined around the outer surface.
Repair stage 2 part number 000 071 02 94 identified by 2 grooves.

[wolf_walker]

Originally Posted by Rick76

The float valve seat is repairable.

Two repair sizes are available (or used to be).

Repair stage 1 part number 000 071 01 94 identified by one grove machined around the outer surface.
Repair stage 2 part number 000 071 02 94 identified by 2 groves.

That's interesting, saw no mention of it in the FSM.
It wasn't so much that mine is worn and not working, just that it came out of the casting. I don't think pressing a brass piece into an aluminum piece
on something that gets hot and cold constantly is a wise way to do things
myself. But hey..

[tram]

OK, so reviving a Solex 4A1 thread from little over a year ago...

I have a 1974 280C with the Solex. All of a sudden things went belly- up out of the blue one day. Would run at 1/2 throttle or better, but would NOT idle. Pulled the dist. cap and found bent/ nearly closed points. Adjusted points, ran great. Decided to do a full tune, incl. checking valve adj., so ordered parts.

When I got the parts, I went to move it into the shop. It was a BEAR to start cold- lots of pumping, lots of false starts. Did the tune incl. points, cap, rotor, wires. Started it, acted like it was running on 4 out of 6.

Long story short, after laboriously checking and double checking firing order, timing, dwell, etc. I pulled the plugs. #1 was fouled, 2 and 3 HAD been fouled but cleared themselves, 4 looked good, 5 looked lean, 6 was cold and white!

After taking the carb off and opening it up to check things, blowing thru all passages with carb clean, etc. I reassembled it and here's what I find:

When it's running (barely) with the choke open, the primary barrel closest to the engine is pumping/ spraying gas into the inner circle, almost like the pump is injecting fuel directly into the engine on each pulse. The outer side barely dribbles.

I've adjusted the float level and changed adjustments, but nothing does any good. The engine makes a heavy Pop-pop-pop noise out the exhaust- detonation. When I cover the intake horns with my hand, it picks up and runs on all 6, but up, down, all around.

I've checked for warpage, but this carb doesn't seem to be a victim of that. And, when I take the top off (gently so as not to harm the gasket!) there's no excess fuel in the bowl, so the N/S seems to be working.

I don't think this carb should be dripping/ spraying fuel like this at idle- should it? Or is it the side that is NOT spraying/ pulsing that's at fault? Everything I read up on and put back into spec seems to actually put me farther back. Don't really want to go Weber, and good used or reman Solexes just don't seem to exist. Any ideas? Thanks in advance!

[ctaylor738]

If you are sure of your float adjustment, fuel coming through the primaries at idle, can mean that the idle air passages are plugged. The engine is producing vacuum and demanding fuel, so if it can't get it through the idle circuit, it will pull it through the main jets.