Solex Carburetor

The 4A, 4AB, 4AC, 4AD cars, including the SM 1500 Roadster and SMX
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Stephen
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Joined: Thu Feb 03, 2011 9:27 am
First Name: Stephen
Location: Victor Harbor, South Australia, Australia

Solex Carburetor

Post by Stephen »

Hi Everyone .. After major restoration the 1952 Singer 4AD is on the road and well on it's way to getting reliable, but still have one small problem..

The engine has a single Solex 30 FA1 / B46 carburetor
Each time we take it out for a long run, it performs well on the open road but when we hit the city limits at the first stop light the motor dies,
It will start OK again, runs rough, and will not idle, .. adjusting the fuel mixture makes no difference, so we bump the idle screw up each time to keep us going.
After each trip, I start the car up in the shed and it idles great when the engine is warmed up. Take it back on the road for a trip and it cuts out at the first stop.

The original carby was cactus, but I managed to pick up the present carby from a swap meet... it was new old stock, and the label on the box said it was for a 1956 Ford sidevalve .. I took all the jets from the original solex carby that came with the engine, including needle and seat and put them in the new carby .
The only difference between this carby and the original, was the choke cable came in from the opposite direction.. so I reversed the choke mechanism and it seems to work OK ..

Has Anyone out there experienced the same problem, and has a solution ..

Regards
Stephen
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kabu
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Re: Solex Carburetor

Post by kabu »

Hi Stephen,

I had similar problems occasionally when I got my car on the road after restoration. My car is with the twin carb setting, it would idle and work perfectly well but would stall on the first stop on traffic light after a while on a higher speed. I rechecked the carburetor and ignition settings and adjusted the carburetor volume screws according to the factory manual and the problem disappeared.

Since you know that your carburetor is from another car originally, I'd suggest that you check that the settings and jet values are correct. The values are stamped on each of the jets.

This is the carburetor settings for the single carb engine
Carburetor Solex 30FAI
Choke: 24
Main jet: 125
Air Correction jet: 230
Pilot jet: 45
Starter Petrol: 115
Starter Air: 4
Emulsion tube: O

The factory manual states the volume screw setting as following:
Normal adjustment is carried out as follows:
1. Wait until the engine is hot
2. Set the throttle adjustment screw until the idling speed is on the high side
3. Slacken the volume control screw until the engine begins to hunt
4. Screw it in very gradually until the hunting just disappears
5. If the engine idling speed is too high, reset the screw to slow it down to an idling speed of about 500 r.p.m
6. This may cause a resumption of slight hunting. If so, then turn the volume control screw gently in a clockwise direction until the idling is perfect.
These adjustments must never be made with a cold engine

One thing you could also check is that the float moves freely and the needle valve works correctly.

I still left the idling speed somewhat higher than the stated 500 rpm, around 700-800 I think.

Regards,
Pekka
4ADT Roadster, 1954 --- http://www.guru-group.fi/kabu/singer
Stephen
Posts: 164
Joined: Thu Feb 03, 2011 9:27 am
First Name: Stephen
Location: Victor Harbor, South Australia, Australia

Re: Solex Carburetor

Post by Stephen »

Hi Pekka,.. .. I will be in the shed tomorrow to pull the carby off and go through it and make sure it has the specifications you have listed and run it again to see if it fixes the problem.
One thing I did not mention was that when slowing down to a stop light after a long run, the motor backfires as well before stalling ..
Will post the results in a few days after I work on the car and get a chance to take it out for a decent run weather allowing ..

Thank you for your help.
Stephen
Stephen
Posts: 164
Joined: Thu Feb 03, 2011 9:27 am
First Name: Stephen
Location: Victor Harbor, South Australia, Australia

Re: Solex Carburetor

Post by Stephen »

Hi Everyone,.. I finally had a chance to take the Singer on a long run to see how my carby restoration went.
As per Pekkas list above I had a few old solex carbies laying around, not fai 30's but it looked like most of the components are interchangeable from one model to the next.
Choke 24
Main Jet was 107 went to 120
Air correction 230
Pilot jet 45
Starter petrol 115
Starter air 4
Emulsion tube ? could not get it out of the carby so do not know what is in there.
The car starts first time all the time, it idles a little rough, but after 2 long runs, 20 klm each way when it dropped back to idle it did not stall or stop, so I am going to say Problem Solved.
I also made sure where it sits on the manifold was bolted securley and it had gasket goo .
I also tightened the manifold bolts, all the bolts had to be nipped up, and 3 were loose, so it may have also had an air leak

Stephen
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mikeyr
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Re: Solex Carburetor

Post by mikeyr »

most of the jets are the same as the original VW bug motor, the old 40HP motor.
Mike Rambour. Site Administrator
1953 Singer 4ADT (sold), 1934 Singer 9 Le Mans, 1934 Singer 1 1/2 4-Seater Sports (sold), 2009 BMW K1300GT
Stephen
Posts: 164
Joined: Thu Feb 03, 2011 9:27 am
First Name: Stephen
Location: Victor Harbor, South Australia, Australia

Re: Solex Carburetor

Post by Stephen »

Thanks Mike,.. my wife has a 61 Beetle Hmmm!, no I had better leave it alone, I'm too old for a divorce and too young for a funeral ..
Stephen
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