Morris Minor Owners Club

Well it should have 3 screws, I will get a picture for you.

Whoops sorry mine has 3 because its an HS4 you have the standard HS2 which does only have 2 screws.

OK thanks, if it's supposed to have three and one has dropped out could that be causing my problem? As I say, the two screws I've got are directly opposite each other. When I took the second one off the suction dome came away so obviously I didn't look for a third one. I'll go out and have another look.

Kevin wrote:Whoops sorry mine has 3 because its an HS4 you have the standard HS2 which does only have 2 screws.

Drat!

Going back to the piston, there is a small scuff on the bottom edge, but literally only 5mm if that. There was a tiny amount of black residue here and there in the grooves which I cleaned out with white spirit and a small (carefully wielded) screwdriver. The piston clunked up and down in what I take to be the approved manner.

I can't help wondering if this elec ignition thing isn't a bit of a distraction. The fact that it runs fine for 10 mins would surely mitigate against this theory?

Am going to put up a pic of the rotor arm in a minute

Could this be the culprit?<br><br>

Another view - are they supposed to have that chip in the plastic? <br><br>

give it a clean with some scrathy paper,or replace it if you can get hold of one,whats the dizzy cap like inside,are there ware marks on it.

Generally - they either pump, or they don't pump

True, but the first time my fuel pump caused a problem it lost power and restarted and ran a mile or so on three occasions before I had to get the hammer and sandpaper to it.

dalebrignall wrote:give it a clean with some scrathy paper,or replace it if you can get hold of one,whats the dizzy cap like inside,are there ware marks on it.

Old dizzy cap looked OK Dale but I had a new one in the shed so I just bunged that on anyway, so that can't be it (even as I write that I'm wondering 'or can it?'!!). Am cycling into town now to try and get new rotor arm on same belt and braces principle, then I will have a look at the petrol pump points as that's been mentioned a couple of times now. Thanks again to everyone, having all this knowledge on hand is very reassuring.

The rotor arm looks ok - DO NOT clean it with emery paper or similar (ok on the brass tip though) - the plastic must be smooth and unblemished. Try rubbing some oil over the plastic - this is 'old trick' that can resurrect a tracking rotor arm (or dizzy cap) as a get-home measure. The idea of blaming the electronic ignition is that some component in there may be heating up - and then failing. It's ok when cold - fails when hot. You've pretty well checked everything else !

I see what you mean about the elec ignition. Luckily the local motor factor did have a new rotor arm, so I'm putting that in now and will go for a quick test run.

I'm a little bothered by the markings on the rotor arm around the area where the cap's centre brush should contact it. The brass is far too polished, and at a much greater radius than I'd expect. Might the rotor arm not have been seated correctly - perhaps even with its spigot not located in the shaft slot? Is the centre carbon brush in the cap present, or could the marks have been caused by its spring?

If there had been any tracking, it might have been visible on the inside of the hole in the rotor arm - perhaps a barely visible dark spidery lineshowing the path of sparking internally to the distributor shaft.

The missing bit of plastic looks odd, too. Could it have rubbed on the cap? Have you checked for any witness marks on the inside of the new or old caps?

Incidentally, OP (original poster, indeed). please don't misinterpret comments about levels of experience: I, certainly, am still learning after far too many years. And Louise, yes, I should get out more, but no-one asks me any more...

Kevin

Just fitted a brand new rotor arm which has exactly the same chip out of the plastic so must assume this is a design thing. Anyway, that's another thing eliminated. Have had a look at petrol pump contact points, no sign of corrosion there, spring blade and springs on rocker ass'y seem OK, only bit of corrosion was on spring washer under the nut that holds the plastic cover on, gave it a gentle wet+dry blowover and put 3 in 1 on it just for the hell of it. Have also pulled out sagging double-thickness soundproofing from under bonnet and replaced single sheet with lots of double-sided sticky, so that's not hanging down any more. Air filter turned to 'summer' position. New coil. New distributor cap. Plugs OK. So off we go to the local fete and let's see what happens!

i have quite a few old stock rotor arms and they all have the plastic bit out as in the pic

This tale is being told on a parallel separate thread (sorry to the webmasters) but for those who haven't seen that (and are interested!) I've just been out again with all the new bits and it is a lot better. Last things I did today were to (a) check fuel pump points (they looked ok but gave them a light twiddle with a very fine bit of wet and dry anyway), (b) take out sagging double-thickness underbonnet insulation and re-stick in single piece (in case it was starving the engine of air) and (c) put in a new rotor arm. Unfortunately I didn't do a test run after each of these jobs, which would have been ideal, time wasn't on my side, but I have a feeling (and it's only that, a feeling) that the new rotor arm was the most significant event. There's still the occasional stutter, which seems to happen mainly when coming out of slow bends in 2nd, but I feel a lot more confident about reaching my destination now. Sincere thanks to everyone who has chipped in information, I think I made use of all of it! I enjoyed the process and wonder if the car was teaching me about itself by presenting me with these little foibles to try and resolve. I certainly wouldn't have got this far without this amazing website and the wonderful people on it. I hope to be able to thank some of you in person at Sparkford next weekend.

Well - if you think it's fixed! Good luck with it.

Who knows really, it's not perfect, but then it is a 40 year old car – and mine's one of the young whippersnappers at that! Thanks Roy, your help was invaluable.