Morris Minor Owners Club

Am having trouble with getting the right idling speed for the engine, it seemed to be far too high, so have adjusted the idling screw down and also weakened the fuel mix, as the exhaust was coming out black.
The engine still sounds rough, and makes the rear view mirror and front grille vibrate when I am stationary.
Have also had a comment from a passing ex-minor owner that my engine doesn't sound right, but am at a loss as to what to do next! Any advice much appreciated.

Mine was running like a tractor until I got it fixed by the boys at the National First major thing they found was a load of nasty gunge in the carb. Dug that out and then they took the fuel pump to bits to get the stuff out of their as well. Put new points into the fuel filter. There was also a trick with the air filter which really blasted the carb out and its been a different animal ever since. So you might just have a fuel problem. Other more experience people will be much more capable advising you. Good luck

8009STEVE might be able to tell you more - he worked magic with mine!

Are you sure it was the idle screw you adjusted?
The fast idle screw is more prominent and if you adjust it the choke will start to operate and you wont be able to set the mixture properly.

The fast idle doesn't make the choke operate - no fears there - it does however raise the idle speed, when the choke is pulled, to ridiculous levels - so it's a very valid point, and should not be used to set the normal 'hot' idle speed.

Rough running could be so many things Geraldine, could be carb adjustment or ignition problem (points, distributor cap,condensor, plugs, plug leads all ok?) or one or more of the tappets closed up a bit? Damper on carb topped up with thin oil? Is it only the idling that's rough? Cruising ok?

The colour of the sparking plugs is a good indicator for the mixture being right, is it black and sooty(too rich) or coffee colour(right) or greyish/white (too weak)? Have no 1 plug out and have a look at it after a run
If the car has not been serviced for a while a complete service kit is very cheap and you can start to eliminate some of the likely suspects

Geraldine, where are you?

It may be the engine is only running on three cylinders - so i would take ALL the plugs out and inspect them. If any are 'wet' - then they have not been firing.

he worked magic with mine!

Thank You Ani

The pleasure is all mine Simon had a small hic-cup with it yeterday when he got caught in a long tailback. It got fairly hot and then going up a hill he detected a slight hesitation. After stopping for a short while all was fine again. I'll probably give it a test tomorrow - do you think it possible that there could still be any muck left around? Anyway I'll go away from this thread while you wait for Geraldine to come back. Might see you at Ringwood??? (Dorset Rally) next weekend.

Thanks everyone for your replies, as you say it could be so many things!
We looked in the manual to adjust the idling speed, which screw should we use if not the fast idle one? We turned the top screw, My husband says there is another one further down!
Pretty sure she is firing on all cylinders, and once the engine has warmed up she runs OK. Took her for a longer run yesterday and she ran quite smoothly once we got going. I will check the plugs next time I take her out.
Cormorant, where would I get a complete service kit, not sure what this consists of! Hubby has quite a few tools for his motorbike, so probably have some of it already.
I am in Ipswich, Suffolk.

Service kit from Bull Motif - or other suppliers. Shop around - there are somtimes some 'special offers'.

The service kit gives you oil filter, air filter, points, condenser, rotor arm, distributor cap, plugs so this covers quite a few of the bits that could help on the electrical side. If the car runs well but just has a lumpy tickover maybe the adjustment is just off? Don't wind the jet nut in or out wildly under the carb, just go a flat or two at a time - wind up to weaken, wind down to richen.
I tend to set mine on a sort of try it and see basis, look at the plugs, test drive etc until it is just right, I am sure someone else can give a more scientific method for adjusting the SU carb that is quicker. If you look at the plugs this is a good guide and you can then adjust the jet up or down as needed then adjust tickover again as this will be affected. Then wire brush plug off and try again. Also do you keep an eye on the fuel consumption, I am getting 38mpg which according to the book is pretty spot on, also not a bad guide to correct adjustment

Only use a very soft 'brass' wire brush on plugs! Better to do nothing - just pop them back in.

Only use a very soft 'brass' wire brush on plugs

Never had one of them in my tool kit!

I have a lovely little soft brass wire brush it's lovely and soft, just like a little kitten. Now I am going off to do something useful

The type used for suede shoes ! Wire brush damages the ceramic. Best way of course is bead blasting - but not many of us have that.

8009STEVE wrote:

Only use a very soft 'brass' wire brush on plugs

Never had one of them in my tool kit!

Never worn suede shoes either I suppose Steve

Nope, not even blue ones.

Don't you mean not even oil stained ones

Hello again, am still having problems, I think we must have fiddled with the fast idle screw because now when I start with full choke it sounds awful, really "chugging", and the ignition light won't go out (maybe am draining battery?) When I put the choke in the chugging stops but engine is quite fast, and ignition light nearly goes out. Also a distinct petrol smell when engine running.
Trouble is I have looked at the manual and it shows a slow running screw in the diagram, presumably this is the one I should be adjusting - but I can't find it, my carburettor looks different to the one in the manual!
Guess I'll have to take it to the garage, have messed it up completely!