Thread: Solex Carby

I am still having these problems which I have not been able to resolve. Since my last post the car has been looked at by a carby expert and supposedly all is OK but the spark plugs are still sooted up so looks to be still running rich.

Went for a drive up a steep hill nearby (Black Mountain in Canberra) and the engine kept on loosing power - foot flat to the floor and it would start loosing power - backing off made things run a little better but when the engine died it would fire but not run - pointing downhill and all was fine. Engine runs fine on the flat and moderate hills but not steep hills.

The Carby is laid out the "right way" as in the top right diagram when going up hill.



My thoughts are that the engine is getting too rich when going up hill. So on the Series 1 32mm version of the carb, how do you adjust the float levels as I am thinking mine is a little too high. The floats in both carbies do not seem to have adjuster tabs. Also can anyone advise the psi that the series 1 fuel pump runs at - the electric pump I have may have too high fuel pressure.

As this carb is not the correct carb for the engine I have decided to get rid of it and get an original which is not easy to find. The closest is a carby off a Unimog 404 which I have purchased and it is in the mail to me. Should just need a kit and some rejetting.

Appreciate comments from the Series 1 Solex experts.

Cheers

Garry

According to a scan Mike from Gippsland posted years ago, the fuel pressure must be between 1 1/4 psi to 2 1/2 psi.

It appears from the article, that the float level is not adjustable as you found out. Check that the float arm is not bent or the float punctured,

Cheers Charlie

On level ground after running the engine, first disconnect the fuel line, then carefully lift the top of the carby and measure the distance between the fuel and the top edge of the float chamber.

.

Originally Posted by wrinklearthur

On level ground after running the engine, first disconnect the fuel line, then carefully lift the top of the carby and measure the distance between the fuel and the top edge of the float chamber.

.

Thanks - will do that but what then . What sort of difference in height between the two levels should there be and if it is not right what can be done to adjust the level?

Cheers

Garry

Originally Posted by wrinklearthur
On level ground after running the engine, first disconnect the fuel line, then carefully lift the top of the carby and measure the distance between the fuel and the top edge of the float chamber.

.

Originally Posted by garrycol

Thanks - will do that but what then . What sort of difference in height between the two levels should there be and if it is not right what can be done to adjust the level?

Hi Garry

Is this picture the same as your carby?


By getting your measurement, we can then compare the specifications for that model carburettor, if the fuel level in the float bowl is found to be about right, then maybe either the throttle body and/or the jets would need changing.

Another couple of measurements that would be handy, are the manifold vacuum levels at a range of revs at working temperature.

If the inlet manifold isn't at the correct working temperature, then the petrol wont vaporise properly either and this shows up on the spark plugs as a sooty deposit.
.

Originally Posted by wrinklearthur

.Is this picture the same as your carby?


By getting your measurement, we can then compare the specifications for that model carburettor, if the fuel level in the float bowl is found to be about right, then maybe either the throttle body and/or the jets would need changing.

Another couple of measurements that would be handy, are the manifold vacuum levels at a range of revs at working temperature.

If the inlet manifold isn't at the correct working temperature, then the petrol wont vaporise properly either and this shows up on the spark plugs as a sooty deposit.
.

Thanks - yes that is the carby.

Unfortunately not in a position to check manifold vacuum levels as I don't have any gear that can do that.

Heating of the inlet manifold is via a pipe that directs a small amount of exhaust gas from one exhaust port to the other and heats up a plate that the carby sits on. I will get my laser temp reader and see what temp it gets up to after the engine warms up. However as I indicated the engine runs fine in normal use - just plays up on steep uphill climbs.

I will get post up my checks probably tomorrow.

I appreciate you input - thanks

Garry

you have an emulsification, float or vent problem on the main fuel bowl.

when the throttle snaps shut the increase in vac is drawing excess fuel down the throat and flooding you out.

I have a manifold vac gauge you can borrow.

Originally Posted by Blknight.aus

you have an emulsification, float or vent problem on the main fuel bowl.

when the throttle snaps shut the increase in vac is drawing excess fuel down the throat and flooding you out.

I have a manifold vac gauge you can borrow.

Dave - thanks for you input but the issue is happening when the throttle is open powering up a hill not closed, however I do agree that excess fuel is going down the throat and flooding the system.

My understanding of a manifold vacuum gauge is that it needs to have access to the manifold after the carby or at its base - in my case there are no ports like say there are on a Rover V8 manifold- the manifold is just a piece of mild steel pipe with a plate welded on where the carby is bolted. I guess I could drill a hole into it and create a port but at this stage I would prefer not too.

A general question - seeing there is no adjustment on the float - what would happen to general drivability (noting it is flooding on hills) if I effectively lowered the float level and hence the amount of fuel in the float chamber by soldering a bit of solder on the float arm where it lifts the float needle.

Cheers

Garry