Morris Minor Owners Club

a few weeks ago, my motor developed a cough.
i have checked the timing, the valve clearences and every other thing i can think of.
could it be a burnt valve?

it only seems to occour when the engine is cold, and once i floor the throttle, it goes or when it gets warm it goes as well.
safe to say it has me stumped

Did you ever get a compression check -I can't remember!

It has swine flu
Cough is a bit tricky to diagnose in an engine. Does it miss at tick over? or hesitate on acceleration? Or something else?

yep, got a compression check and it was around 150psi for each pot.
on tick over, it runs fine and dosent hesitate on acceleration. when i am traveling at a constant speed when the engine is cold it coughs, but when i accelerate it goes.

What colour are the plugs ? And - have you tried a different set ?

Slightly weak mixture seems favourite.
When you accelerate the mixture is richened a bit.
However things change as they warm up, metal expands and takes up slack curing broken wires and wrong gaps.
Do the symptoms appear as soon as you push the choke in-> Weak mixture.
Otherwise, something else.

I had exactly the same problem, took her to the garage who adjusted the timing, tried adjusting fuel mixture and idling speed, had compression check etc. which was OK. Got a little obsessed with it.
She still sounds a little rough when first starting, but have learnt to live with it as she runs well apart from this and has never let me down. Just one of her eccentricities I suppose.

Good point Geraldine, the amount of choke and how long it needs to be applied for is individual to your car.
You need to find out what combination works for it.
The choke isn't an on/off switch.
This is part of the character of your car and will help keep "tea leaves"* off your it.
See what the car likes, and go with it.
As a slight aside, I was amazed how much this changed after I adjusted the tappets properly.





* Thieves for those not of an East End dispostion.