Morris Minor Owners Club

We recently (400 miles ago) had the cylinder head skimmed and replaced all valves and seats and have since been driving like a dream until this morning...

Imagine the scene, beautiful Derbyshire countryside, rolling hills as far the eye can. Unfortunately the eye can't see very far as we are slowly leading a queue of irate commuters at a funereal pace towards Sheffield.

Now, I suspect Intermittent loss of power and occasional juddering can probably be accounted for by the need to retighten the head or similar. New HT leads, dizzy cap rotor arm etc fitted 2,000 miles ago.

Can anyone explain this - with the choke in we would still be sitting somewhere in the Peaks, with the choke fully out we managed to limp home at top speeds ranging from 45 to 8mph (not all accounted for by the hills!)

Try changing the rotor arm, 2 minute job - may not be this but this happened to me. See previous post under electrical section 3 to 4 months ago.
Nigel

If you mean that by pulling the choke out the engine ran - then that would indicate a lack of fuel getting into the engine.

Would suggest checking fuel pump first.

Let us know how you get on.

Steve.

regtubby wrote:-snip-
Can anyone explain this - with the choke in we would still be sitting somewhere in the Peaks, with the choke fully out we managed to limp home at top speeds ranging from 45 to 8mph (not all accounted for by the hills!)

one possibillity suggested by the fact that the choke kept the car going is a faulty/ leaking inlet manifold gasket, or one of the gaskets leaking between the carb/ spacer, throttle holder thingy and manifold.

If one of these is badly leaking air directly into the engine your car will be running a very weak mixture and hence the choke helped redress the balance.

I trust all these gaskets were renewed when the head was changed?? (and all the old bits of gaskets scraped off??)

Try tightening up the manifold nuts and then the two carb nuts.

The fact that the choke had to be pulled out i.e. lowering the jet so that more
fuel was available suggests that the needle and piston were not rising up as
they normally would. This could possibly be due to the carb icing up(have you directed the air filter pipe towards the exhaust manifold for the winter
months) or a sticking piston. insert your finger into the carb intake and lift up
the piston to the top and then see if it drops with a soft 'plop' any sticking of
the piston should be investigated. I have had a problem before now withthe
piston damper unit preventing the piston from rising but, as long as it has the
sufficient amount of oil in it and the assembly does not stick when you use
your finger this can be discounted. If it was a fuel pump problem I cannot
see how pulling out the choke would have any effect on the pump. The worrying thing is that you have recently refitted the cylinder head. If you used a copper head gasket then have you retightened the head nuts after the
first 500 miles? If not then it is quite possible that the new head gasket is
leaking.

That is pretty much what happened to me the other month, with a tremendous loss of power and a great deal of juddering. One of the valves on no.3 had cracked and chipped. As a worst-case scenario, it may be worthwhile whipping the head off and seeing if there's anything untoward.

Thanks folks.

We fitted a new carb at the same time as the head was done and yes we did us a copper gasket with a view to tighten at 500 miles maybe that should have been 400!

Engine started first go and idled nicely, it was only once we started moving that we had problems. No sign of mayonnaise or oil in the water and by January standards it was quite warm this morning, no sign of frost of ice, probably on account of the absolutely torrential rain we had all night.

We have used more oil than usual since the head was fitted - Max to Min in 400 miles.

Gareth, I had a look at your thread from November re similar problems and found it very useful.

I'll have a good look at the weekend it was dark and wet this morning and I was somewhat late for work.

It does rather sound like carb icing. Is you had stopped and let the angry mob past the ice would have melted and all would have been well again! If you go to the car now - does it run ok now ? Wet/cold is the ideal condition for carb icing.
Otherwise - if the engine was/is very rough then it could well be blown through between 2 and 3 - turn it on the handle and feel if there is even compression on all cylinders. Also worth checking the valve clearances - in case they have closed up. Could also be points closed up or just water on the ignition leads.