Morris Minor Owners Club

Hi everyone.
Can someone give me some advice please?
The engine seems to be shaking a lot when it's idling and I'm under the bonnet checking things out. I can't hear any knocking noises, although it is a tad on the loud side (sounds like a diesel!) The idling is also quite irregular and the exhaust note isn't consistent. It's kind of like puffing and popping.
Is this the timing? I've adjusted the jet nut on the carb and adjusted the idle screw to try and get the best running from it and is certainly running much better than it was when I got it, but it still isn't right!
I'm really grateful if anyone can help!
Thanks,
Steve

Could be all manner of things! Valve gaps closed up/valve (and/or seat) burned/oiled up spark plug/poor HT leads/poor dizzy cap/poor rotor arm/tight points gap/timing miles away etc etc. Ideally a compression check should be done - after resetting the valve gaps - to determine the general health of the engine. But I would inspect the plugs and perhaps fit a new set as a first step, then check the valve gaps.

I changed the spark plugs to new Champion ones as the NGK ones were really black/dark brown. Unsure if it was oily or just too rich. One thing I have noticed is that just after a few runs the tip of the spark plug in cylinder 1 (haven't checked the other ones yet) is all white while the threads have a darkish residue on them

And did it run better on the new Champs ? Or is it just the same?

It did actually seem to run much better on the new ones. The old NGKs were very fouled though

Never liked NGKs - but i doubt they are the root cause problem here!

Engine is clearly misfiring, could be either electrical in cause (we hope!) or mechanical.

Test for a spark on each cylinder, I have one of those set of spark testers that you put between the lead and plug and they light up if you have a spark. If one cylinder is not sparking then it is possibly the lead needs replacing (change the whole set!) or the distributor cap.

Get a service kit from one of the usual suppliers and try a new distributor cap.

Misfire on idle-
My bet is that you have a burnt exhaust valve- test the compression on all four cylinders and if one is down (most likely the one with the different coloured plug) then you have your culprit.

A new valve and gasket set will then be needed, while the head is off, lap all the valves in.

Thanks for the advice.
I did a compression reading on all 4 cylinders from cold and got 140 from each.
I bought a colourtune device for setting the mixture and while checking the colour, the sparking was very irratic and wasn't in time i suppose it could be skipping a few sparks.
I think next step is to try some new leads, dizzy cap looks fine though, the points are nice and clean and not pitted.
Sorry to be thick but was does lap the valves in mean? Also how would I solve a burnt exhaust valve?

Well it doesnt seem like there is an iffy valve if all the readings are equal, if you sparking is erratic you are getting to the problem from the sounds of it, you may have an iffy low tension lead have a close look at it as they can go under the insulation, if the points are clean it probably means the condensor is ok, check the rotor arm closely and I know you have checked the dizzy cap but sometimes they can crack and be difficult to see, I would start it up in the dark and look under the bonnet to see if you can spot any electrical tracking as this may reveal the problem.

Yes - compressions although not brilliant indicate no gasket or valve problems. As Kevin says - overhaul the ignition - that's where the problem seems to lie. One way to do this is to fit a complete new dizzy such as this screaming bargain http://cgi.ebay.co.uk/New-Morris-Minor- ... 27b5487b40. This will upgrade and replace everything (except the coil) in your ignition system - and is excellent value for money. It will save hours of searching for the problem - it's ALL new and guaranteed.

That's good news, at least it's not something more serious under that rocker cover! Although I may have a look at setting the valve gaps tomorrow. Would the faulty ignition also count for the backfiring I'm getting?

Indeed it would. Backfiring is simply unburned fuel - pushed through into the exhaust - and then ignited there when the ignition picks up again.

Well I had a good look at the car today. Changed the HT leads and for good measure whipped off the rocker cover and checked all the valves were operating properly by turning the stating handle but they were all fine. Still running like a horse with one leg! Thoughwhen starting from cold with the choke slighty out I noticed it runs much better at idle. Could it just be that the mixture is too weak? Think I'm going to have a better look/change the distributor. Firstly by trying to adjust the ignition timing.

Could it be the timing chain is slack has jumped a tooth? That in itelf would be noisy but it would throw out the combustion timing relative to the valve timing which could be creating aditional noise too.

My previous 950 cc ran like this. I carried out all the cleaning / checking / changing of electrical components as described above and the engine was transformed. I did not do the timing to the recommended settings though; I slackened the lock nut on the distributor, moved slightly to get the smoothest idle and locked it up again. The end result was a much smoother, faster, quieter engine.
Any reputable mechanic should be able to do this quickly and quite cheaply for you if you are not mechanically inclined.
Good luck, Will .

That is a good starting point for the dizzy timing - but do check the engine isn't 'pinking' under load! Also always worth checking if the vacuum advance is working.

I bought the new dizzy off eBay as recommended by bmcecosse (arrived really quickly too) slotted it in without a hitch and reconnected the vacuum advance with a new piece of rubber/plastic tubing rather than the screw-on metal one. I've buggered up the timing though, so it doesn't idle properly now without the choke being out. Gonna have a look at it again this weekend to see if i can statically set the timing and take it from there

Once the engine has warmed up, push the choke in and turn the tickover screw up. When you have adjusted the distributor and got it idling smoothly turn the tickover back down and adjust the distributor a small amount to keep thengine running smoothly.

Can anyone advise on how to statically set so I can fine tune while running? Where should the rotor arm be in relation to the sparking points? In the middle of it, or should it be at either end?

I don't actually understand the question but static timing is used as a baseline to start the engine. As you can start yours the next step is dynamic timing as described above.....