Morris Minor Owners Club

HI,

Just been out in George and the engine seems to be running too fast. When I pulled the choke out it didn't seem to make any difference to the revs.

Does this mean the mixture is running rich and the choke cable is not working?

What should I be checking for? I will have to read my manuals and look tomorrow when I give the engine bay a clean!

Have a look at the bottom of the carb when someone is sat in the car pulling the choke cable. you should see the base of the jet move up and down. Possibly it has got stuck.

Sounds like the tickover is set too high.

Alex'n'Ane wrote:Sounds like the tickover is set too high.

Sorry, I didn't say that it only started running fast today!!

I will try the choke cable first.

Mine has the throttle return spring connected to the exhaust clamp. Check to make sure this spring is tight enough to close the throttle bit on the carb.

1. check the tick over screw as previously mentioned.
2. check the spring to the exhaust clamp.

Ok, I got my son to sit in the car and pull the choke lever out and in. After he had pulled and pushed the lever a couple of times the idling speed went back to normal and the revs increased every time he pulled the choke out.

Unfortunately, the manuals and restoration books assume that the reader has a good knowledge of the car and knows what everything is and does etc.

What I need is photos of the elemetns of the engine and all the different systems as they would look if they were perfect. That way I could match the photos up with what I have (taking into account that everything will be alot dirtier and worn)

What I did notice was that a cable leads from the vacuum unit on the distributor. It has come loose and the only place it seems to fit is on a rubber elbow joint at the bottom of the carburettor (this rubber elbow is loose). Did I do the right thing in connecting the cable up to the elbow? I can't seem to find out what it is for!!

It sounds like the vacuum pipe came loose, which could cause the revs to go up at idle. Try taking the pipe off again and see if the problem returns!

Will do thankyou

Another possibility is that air has started to leak into the carb body from a worn throttle shaft, but this wouldn't normally start suddenly.

I'm trying to work out why mine's doing the same since I stripped and serviced the carb. It has a new needle, jet, the choke and return are all fine, the throttle returns fine and the adjustment is set as low as possible and still it revs its 8&{{$ off when I star it.

Where's the best place to kick one of these things?[frame][/frame]

Is the throttle plate correctly centered on the shaft -is the 'fast idle' screw set too hard down - slacken it right off.

Also check the throttle plate is the right way round on the throttle shaft, it can be put in upside down.

I wonder how you know that Picky........

bmcecosse wrote:Is the throttle plate correctly centered on the shaft -is the 'fast idle' screw set too hard down - slacken it right off.

When I know what the throttle plate and the fast idel screw are I will have a look

Thank you

Julie

Well, I have found out the problem. It was the jet screw. One of my friend had a moggy many years ago and gave me a hand. I have learnt where the throttle cable attaches to the carb and how to adjust the jet screw. There was also another screw the same as the jet screw further round on the carb but my friend couldn't remember what it was. I will have to look it up.

Thankyou for all your help

Jet screw??? You got me there.......???

The SU carb does not have a jet screw. It has two small screws with springs around them. One screws against a stop and controls the tickover speed, the other operates against a moving cam and controls the choke control fast idle setting.
With a warm engine the fast idle screw should be wound clear of the cam and the tickover speed adjusted with the other screw. The fast idle screw should then be wound back so that it is just touching the cam. When the choke knob is pulled out the cam will turn and increase the engine revs to prevent the engine from stalling