Morris Minor Owners Club

I have a problem (occasional lack of power despite engine running) that I thought was down to ignition but I've been through with a fine toothed comb and replaced or cleaned all the parts. How do you check for a blown head gasket? Or any other ideas of what one should look at ? - I hobbled back today, after the car running OK for a mile, at 15 MPH - sort of misfiring noise coming from the exhaust.

Manifold gasket instead? This gives a considerable reduction in power but makes a banging noise.

Symptoms of head gasket failure include visible steam from the exhaust even when thoroughly warmed up, water in the oil on the dipstick and a loss of water from the radiator (provided there are no other leaks in the system due to perished hoses etc).

Is the oil pressure light coming on at all?

Also describe the symptoms in more detail please, 'misfirng noise at exhaust' could be anything from bad timing to a sticking valve.

Symptoms. Well the engine starts and seems to run OK (though all the plugs have started to soot up quickly) With everything clean and dandy when you take her out there is little power. I have recently replaced the engine mountings and have not checked the timing since then but on start-up the engine sounds sweet. There is no water in the oil, nor oil in the cylinder (the soot on the plugs is dry) There is fuel to the carb. The dizzy is all new wiring and new points and the gap is set to 15.

Check/reset the valve gaps - then compression test. But also check the vacuum advance is working as it should - and indeed check the mechanical advance works too. A fault that 'comes and goes' will not be gasket related.

The excessive soot on the plugs and slow running when warmed up to me sounds like far too rich a mixture. The engine hunts and lurches and will not accellerate smoothly or swiftly if the mixture is set too rich. Is the choke returning fully (and the cable and linkage connecting it to the carb)?

Do you need to use the choke to start from cold or can you slightly depress the throttle pedal and start the car?

Slightly depress the throttle and the car starts

What is irritating is that the mixture seemed to be fine - Nice brown plugs - and I haven't touched the mixture control. BUT I have changed the points.
What's the best way to test the vacuum advance?

Air filter choked solid ? Try running without it.

Plugs should be cream/white - not brown....... Suck the pipe - does the base plate in the dizzy move as you suck?

Suck the pipe - does the base plate in the dizzy move as you suck?

Not the exhaust pipe!!

Instead, suck the vacuum advance tube.

Good luck curing the problem.

Cheers
Don

if it starts without the choke,then highly likely that it is far to rich, make sure the choke is not stuck slighly on,push the mechanism to the fully closed position, this may well be the problem,then with the engine warm just lift the little pin on the side of the carb ,just a little, if the engine speeds up and STAYS UP then too rich and you need to screw the adjuster nut at the base of the carb,in one flat then try again,when its set right the speed should pick up for a second or two then fall back.if its miles out Turn the nut all the way in then screw it out counting 12 flats this is the basic starting point on most SU carbs,then its lift pin and adjust a bit at at time till you get it set.If when you lift the pin the engine stops then its too weak and you need to screw it out one flat at a time.GOOD luck

Well - Who pays the Gremlins?

• I've readjusted the Carb - Up tight then out 12 Flats - tweaked till the engine hunted then died away when the uplift button is used.
  Checked the choke linkage
  Air Filter Clean
  Checked the Tappets - one was slightly out. All valves moving OK
  Sucked the Vacuum pie - Dizzy moved OK
  Contact breaker point set to 15
  Cleaned rotor arm
  New Coil, Dizzy Cap, and plug leads
  Redid the dizzy timing - engine sounds sweet when idle(However, the Advance/Retard unit is move horizontal than vertical as suggested in the workshop manual) Presumably I can alter this by moving the plug cables one step to the right on the dizzy cap and moving the dizzy body till the vacuum is upright - if this is essential?
  Checked all the Hi/Low-tension cables - Had a few good shocks - NICE.
  Cleaned the plugs- checked the gaps.
  All the Cylinders are firing.

Engine now runs and the power is OK - BUT... a slight misfiring as she rolls along.
Any last tweak I haven't done? I'm out of ideas.

Not necessary to move the dizzy - leave as is. The fact you 'got shocks' suggests to me the leads are leaking - was it a NEW set ?? Also try new plugs. New rotor arm, new condenser . It's 'never' the coil........... Advance the timing till you get a little pinking as you accelerate in top gear - then back it off very slightly.

Was at a garage pumping liquid gold cursing the misfiring.
A tall guy comes up (looks a bit like the Indian in One Flew Over The Cuckoo's Nest) and asked how she was running.
I explained the problem.
"The dizzy will be a bit worn, open the contact up to about 18. That will cure it".

Guess what? ... It did

I'm now going to fine tune as you suggest

PS re the shocks I got - it was because I had my hand on the lead into the dizzy as I was adjusting it

The HT lead if in good condition really shouldn't give you a shock if you touch it. The wider gap I suppose will compensate to a degree for a slightly wobbly dizzy drive shaft. Glad it worked !