How To: Restore a Morris or keep fit

[pauldavies]

Yes Mike original solex, can't get the air/fuel mix screw to do anything. I have noticed there is a lot of fuel welling at the bottom of the carbi in the choke tube?
Richard Farrant gave me some info which I tried but still no response from the air/fuel mix screw, basically nothing changes when the screw is turned either way?
Paul

[Mike K]

Originally Posted by pauldavies

Yes Mike original solex, can't get the air/fuel mix screw to do anything. I have noticed there is a lot of fuel welling at the bottom of the carbi in the choke tube?
Richard Farrant gave me some info which I tried but still no response from the air/fuel mix screw, basically nothing changes when the screw is turned either way?
Paul

I have some info on the carby , I will have a look and see what I can find out. Is the screw you are adjusting for the idle mixture only ? Or does the screw affect the fuel ratio over the whole RPM range ?

These carbies were a special design for the military , the manual refers to them as "dustproof". Maybe your fuel pump pressure is too high - have you checked it ? The pump pressure is critical. The CS8 uses a Autovac petrol sucking vacuum can on the dash, its a gravity flow down to the carby . If the fuel pressure on the needle seat is too high ( too much pump pressure in your case ) you will experience problems.

[Lynn Eades]

Paul, have you pulled the idle screw out and made sure the drillings are clear.
There will be a drilling across to the throttle plate and one vertically (I have no specific knowledge about this type of carb)
Really you probably need to go through the whole carb, checking the float level, any air correction jets, fuel pressure from the pump compared to specs etc.

[pauldavies]

Thanks guys and much food for thought, the air/fuel mixture screw and the idle screw I have been trying to get some sense out of and I have stripped the carbi a few times and found blocked jets and worn gaskets. I did install electric fuel pumps on and that may be the problem, I don't have the holding tank but the manual fuel pump I can fit to try the theory. Will let you know.
Paul

[Mike K]

The Morris Commercial 1940 book ' repair aids for service vehicles' says:

The FWD C8 should have carby: S.92/164 fitted AKA Solex 40 RFVDL ( strangler vertical dustproof with Governor)

choke 29
main jet 150-57
aux jet 065
jet assembly 12-300


mph in top gear 44
governor 2500 rpm

Get hold of a flat edge and check the flat surfaces of the carby for warpage , this can cause air leaks .

[Lynn Eades]

Paul, about all I know of a Morris Commercial is that they have 4 wheels. However I imagine a mechanical fuel pump and the delivery pressure from one of these is probably about 2 to 3 psi. if your electric pump is delivering any more it can push the needle off the seat and may be giving you a higher than normal float level. This will likely mess up the idle circuit. You might need to fit a fuel pressure regulator? I would put a gauge on it first.

[Mike K]

Originally Posted by Lynn Eades

Paul, about all I know of a Morris Commercial is that they have 4 wheels. However I imagine a mechanical fuel pump and the delivery pressure from one of these is probably about 2 to 3 psi. if your electric pump is delivering any more it can push the needle off the seat and may be giving you a higher than normal float level. This will likely mess up the idle circuit. You might need to fit a fuel pressure regulator? I would put a gauge on it first.

Just to add to what Lynn has written

Some of the older Solex carbies are extremely sensitive to fuel inlet pressure- this I think stems from the days when many cars had the petrol tank mounted in the cowl and the fuel gravity fed down. I found this out after I spent a long time fiddling about with a Series 1 Land Rover Solex carby . In the end the problem ( running rich ) was not in the carby , but in the SU electric fuel pump . The pump spec was 1 to 1.5 psi but it was actually around 3 psi and this oversight caused me much grief along with frustration.

[Richard Farrant]

Originally Posted by Mike Kelly

Just to add to what Lynn has written

Some of the older Solex carbies are extremely sensitive to fuel inlet pressure- this I think stems from the days when many cars had the petrol tank mounted in the cowl and the fuel gravity fed down. I found this out after I spent a long time fiddling about with a Series 1 Land Rover Solex carby . In the end the problem ( running rich ) was not in the carby , but in the SU electric fuel pump . The pump spec was 1 to 1.5 psi but it was actually around 3 psi and this oversight caused me much grief along with frustration.

Mike,
There were two types of SU pump, high pressure and low pressure. For example a Morris Minor had the pump on the bulkhead and was a low pressure, whereas the Mini had the pump at the back near the tank and was a high pressure as it had to push the fuel further. I guess the delivery pressure at the carb equalled out between the two types. If using a SU pump it pays to check what application it was designed for.

regards, Richard