Ignition Problems /Ignition Switch

[svenedin]

I was raining hard all day today so I contented myself with pottering indoors.

I found out that even though the design of the keys has changed in the modern 47SA ignition switches (an FS type key cannot be made to fit a modern barrel as the key will not even enter the lock) the barrels are still interchangeable. So my car now has a new ignition switch but I have swapped the old barrel into the new switch. The electrical contacts are all new and the old key fits so my car stays with one key for all locks.

A little bit of my car's history showing inside the switch. Somebody in the past has tried to force the lock either with the wrong key or perhaps just a screwdriver. The lock barrel guards have gouged into the metal.

Also a picture of the barmy resistance in the run position. 18.9 Ohms! A wonder it ran at all.

Stephen

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[svenedin]

Just for completeness, this is how to remove the lock barrel from a Lucas 47SA ignition switch.

Insert the correct key but do not turn the lock. With a small screwdriver through the hole in the casing, locate the small brass, sprung-loaded pin and depress it. You will not be able to see this so have to do it be feel. Whilst depressing the pin, lever the barrel out with another small screwdriver.

Stephen

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[svenedin]

Longer test drive today and the car seems to be going well. One interesting thing was that after sorting out the ignition problems I had to make a small adjustment to the fuel mixture. The mixture has not been touched at all since long before the ignition problems became obvious. After I sorted out the ignition problems the fuel mixture was a bit too rich. Not so rich that there was black smoke from the exhaust but rich enough to soot up the spark plugs. I am bit puzzled about this but I think I had a rather weak spark for a long time. With the weak spark perhaps not all of the fuel mixture was burning so petrol was basically going out of the exhaust unburnt. Now with a strong spark it is all burning but there isn't enough oxygen in the mixture so some of it ends up as soot. Therefore, it needed a slightly weaker mixture, about 1 flat of the carburettor nut.

Stephen

[Bill_qaz]

I would of thought a weak spark would of given you incomplete combustion and sooty plugs. The improved spark would give you cleaner running, so don't know why you would need to now lean the mixture.
Did you clean the plugs after sorting the ignition or is it residue from weak spark running period?
Are you running standard heat range plugs?

[svenedin]

I would of thought a weak spark would of given you incomplete combustion and sooty plugs. The improved spark would give you cleaner running, so don't know why you would need to now lean the mixture.
Did you clean the plugs after sorting the ignition or is it residue from weak spark running period?
Are you running standard heat range plugs?

It's odd isn't it? I agree. The plugs looked fine after all the ignition trouble. I pulled two plugs after the 4th break down just outside Portsmouth. A nice coffee colour. It was only after I fixed everything that the plugs looked sooty. When the engine ran badly the exhaust stank of petrol so obviously the weak spark just allowed unburnt petrol to go out of the exhaust. It didn't smoke at all but stank of petrol. The spark was dreadful. I fixed the ignition and then saw sooty plugs. I put my trusty Colortune in and tweaked the mixture ever so slightly towards lean. The flame colour inside the cylinder was definitely too yellow. Also checked with carb lifting pin which agrees with mister Colortune. The thing that has changed is the timing. I fiddled around with it whilst trying to fix the issues we had on tour. I think it is marginally too advanced right now. It was set at 4 degrees BTDC but it seemed to pink in high gear on hills (when should really change down) so I retarded twice on the micrometer 1 degree at a time (13 clicks per degree). In theory it should now be 2 degrees BTDC but I need to check. Very annoying really, it was set up so beautifully on a rolling road with an old Jedi master who could re-profile a needle to suit. I don't have those skills! I went out to a club branch barbecue today. I drove there about 25 miles including a sustained 50-55 mph on the M25. Car seems ok but I'm still not happy with hill climbing oomph which the long-stroke 1098 is good at with the right revs. I was chauffeured back by yours truly (so that I could have a drink) and I still don't think it's quite right. The thing is, the workshop manual is only a guide with timing. Fuel is different and my compression is higher than it was for many years. I did check compressions on my return from France. 185-190 psi. A lot more than it was before rebuild and so perhaps it likes to pink. On the other hand, I'm not terribly convinced and it could be any old rattle that I think is pinking! I'll give Xavier a good slug of his favourite tetraethyl lead drink tomorrow and we'll see!

Stephen

[svenedin]

Well after being very pleased with myself that replacing the ignition switch was the end of the troubles it turns out it was not. The car has been running faultlessly for weeks but is currently on the back of an AA low loader being recovered from near Warwick to South London.

I was not driving or even in the car so I had to try to diagnose the problems over the phone to yours truly as some kind of Mission Control.

Until I can look at the car tomorrow in the daylight I am really not sure what happened. Apparently it ran rough, cut out and would not restart. Spark testers (the neon type) suggest there is a spark. Fuel pipe into container and switch on ignition shows the fuel pump works.

It actually broke down twice, the second time irretrievably. The first time it did restart but only by turning the ignition key to the ignition on position and starting it by pushing the solenoid button in the engine bay. Very odd. It turned over fine with the ignition key in the start position but though the engine spun over and the ignition lights were on, it would not fire the engine.

My guess is there is dirt blocking the carburettor jet or jet pipe which is uncommon. The starts from the solenoid is probably a red herring.

Very challenging being on the end of the phone trying to diagnose a breakdown!

Some choice words said about the dear Morris this evening. Little s**t being perhaps the politest of them.

Stephen

[svenedin]

Car arrived back and despite the fact it was very late I couldn't resist a quick tinker. Definitely would not start. Changed the coil for an old one. Started instantly. I need to train yours truly to be able to change a coil. Would have saved a great deal of hassle and a recovery by the AA. Testing of the faulty coil shows a normal resistance of the primary windings and open circuit in the secondary windings. How it "had a spark" as I was told over the telephone is anybody's guess. The spare coil was in the car too. There is always a spare coil in the car. I have been caught out too many times. It is annoying this coil failed as it was an expensive Lumenition one (they are made in Poland Lumention told me and they say they have excellent reliability). The old coil is a Pertronix Flamethrower 3 Ohm resin filled. As yet, I have never had one of these fail.

Stephen

[myoldjalopy]

One school of thought is that old coils are more reliable. The one on my car dates from the 70's by the look of it and the spare is over 70 years old! The old adage "it's never the coil" was only coined when the new, unreliable coils appeared on the market, I don't know when that was, exactly. In over 40 years of driving Minors as everyday cars, I have never had a coil failure (goes off to touch some wood! )
The old, 'proper job' coils can often be found at an autojumble.

[svenedin]

One school of thought is that old coils are more reliable. The one on my car dates from the 70's by the look of it and the spare is over 70 years old! The old adage "it's never the coil" was only coined when the new, unreliable coils appeared on the market, I don't know when that was, exactly. In over 40 years of driving Minors as everyday cars, I have never had a coil failure (goes off to touch some wood! )
The old, 'proper job' coils can often be found at an autojumble.

It's very frustrating. The car was on the way to a 60th wedding anniversary where it was going to be a surprise but it never made it there and ended up back home. Fortunately, the event is not until today so off again the in the modern car but no Morris as the surprise.

I have decided I have strayed too off topic in this thread and I have started a coil specific one.

Stephen