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MG MGA - ignition/engine problems

Hi,

I finally got to drive my MG for a longer distance and really enjoyed it. I noticed that if it idles at less than 1500 RPM, it starts to sputter like it will stall soon. Could this be because it has a 3/4 racing cam?

Anyway, my main question is this. I drove the car, no problems at all. I get home, and I'm parked in the driveway, and it starts to sputter a little at about 1000 RPM. No big deal since it was doing this before, so I turned off the engine. Once I got the garage door open, I couldn't get it started again. After looking around the engine compartment, I noticed that the latch on one side of the distributor cap had come off and the cap was loose. So I put it back on. Now I can start the car, but only if the choke is all the way out and I floor the gas, which wasn't the case before. I idled it for a while and the smoke was really black and the car will stall if I don't run gas it a little - even with the choke out. The engine sounds normal to me, but I'm not a mechanic.

I don't know if this is relevant, but I installed an alternator yesterday.

Any ideas? Like I said, it ran fine until I got to my driveway.
Darian Henderson

Darien;;
Can you not see the obvious. It's your driveway. You can park it in mine and I will fix it so that It can be run.
You may have a float valve in the carb that has started leaking. Leave the key on without starting and if the pump continues with a slow click check the floats for a leaky float or a bad or dirty float valve.
Also check your dist cap as it may have been damaged while it was loose.
Be certain to check the fuel level in the carbs preferably by removing the paistons and visually checking the fuel level relevant to the bridge cast into the carb body. With both jets pushed all the way up the fuel level should be approximately 1/16" below the bridge.Be certain that your jets retract all the way up when you push in the choke.
Sandy Sanders
Sandy Sanders

Thanks Sandy, I appreciate it.

Now it's doing even stranger things, or maybe I just didn't know before. I started it again after a couple of hours. It started up right away, but it runs strange. It sounds like one of the cylinders isn't firing, but to be honest I don't have much experience with that. (Blame Japanese car companies.) In any case, the idle isn't smooth, even at 3,000 RPM.

The smoke is still black. After I stopped it, I noticed that one of the carbs was dripping gas. I believe it was doing this before. Here's the weird part though, after I ran it, I turned the ignition off and the ignition light came on. I turned the key to the on position and the light went off. I did this a couple of times. I then disconnected and reconnected the battery, and the light was back to normal - off when switched off, on when switched on. After I ran it again, it was the same way - the light stayed on when I turned it off.

It seems like I have two separate issues - electrical and the carburetors. I followed the instructions exactly with the alternator installation, but it seems like something is wired wrong, or is my distributor messed up?

On another note, I now have a negative ground car. I lost track of which wire went where. I have one with a blue end, and one with a black end. Which one attaches to the positive post on the (Lucas sport) coil?

Thanks,

Darian
Darian Henderson

Hi Darian. You dont say where the gas is dripping from exactly, but any gasoline leaking from the carburettors means there is some sort of problem. If gas pours out either of the carb overflow pipes, it probably means that there is a problem with that carb's needle and seat assembly. If so, it is quite possible that rust or sediment in the gas has caused the problem. You might want to remove the float bowl covers to check for rust or sediment. If you find lots of either, then you should probably have the fuel tank cleaned out, or at very least install an inline fuel filter between the tank and fuel pump, to catch any junk before it gets pumped up to the carbs. Also, since the distributor cap was loose, check both the distributor rotor and the cap for cracks or damage. It doesnt take much to damage these plastic parts. Good luck, let us know what you find. Cheers, Glenn
Glenn

Darian,

It sounds like the same problem that you had before, the valves in the SU bowls leaking. I suggest that you do not look for anything else until you solve that.
Did you fit an inline filter as was suggested last time you had these problems? Just one of those plastic ones with a paper element. Are the SU bowl valves in good condition?
DO NOT fit a filter between the tank and the pump!
If the filter blocks the pump will stop with the points closed and you will be looking at buying a new pump. Fit it in the fuel line just before the SU's.

Mick
Mick Anderson

Thanks again everyone.

To answer your questions, the gas is dripping from the bottom of the carb and I have an old fuel filter (from the late 70's) on the fuel line in the engine bay. I should probably rebuild the carbs, but is this something an amateur can do?
Darian Henderson

Darian

There is a seal where the gas is dripping. It is easy to replace, and cheap. Do this before doing a full carb rebuild, as it will probably solve the problem.

The seal is Moss part 370-020 in my (old) Moss US catalogue. It's quite a common failure.

Rebuilding the carbs is a fiddly job (lots of small pieces) but if you follow the instructions on Barney then it's quite doable - even fitting new shafts just requires patience and a fine sandpaper if yu have no access to a machine shop.

If the fuel filter is still clear, no need to replace it, but cheap enough to do so (what do they cost?). There are also three filters in the system already, so I never understand why people feel the need to add another one. Check the one at the fuel pump is clean.
dominic clancy

I would not call wire mesh gauze a "filter", but a "strainer".
Paper is the only proper filter. Very tiny particles can cause problems with the SU bowl valves. However, even though the description of the location of the leak is a bit vague, it probably is the jet seals. This car has stood unused for 20 years, seals do not like that. The leak may decrease as the fuel softens the seals and the choke is used a few times, but I would not bet any money on it.

Mick
Mick Anderson

Thanks for the advice.

I solved one problem. I called Moss and they were 90% sure that the regulator on the alternator was bad and told me to send it in.
Darian Henderson

This thread was discussed between 14/04/2007 and 17/04/2007

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