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MG TD TF 1500 - Engine miss #1 cyl

Have run across a 53 TD. Engine has been re-built, has good, even compression, new points, wires, plugs etc. slight wear in dist shaft, but dwell OK.

Engine has a serious miss on #1 cyl, slighter miss on #2. Front carb has substantal wear in throttle shaft, about 1/16" + play.

Is this the most likely cause of miss?
J E LOGAN

I have had a similar problem on my car, where it struggled to reach 30mph. This seemed to come on very quickly, and I went round and round in circles trying to find the problem. The distributor had about 12 thou wear on the bushes when spindle moved from side to side. The bottom gear had an end float of about 40 thou. As time progressed it became more and more difficult to start the engine. Finally I decided to replace the distributor with a modern 45D modified one. On fitting, the car started first time with good idle. Other problems with the carbs have prevented me from giving it a good trial, but it seems promising.
I am not suggesting this is the cause of your problems, but its worth looking into.
Henry

Henry, is it throwing a spark at the plug?

If so try swapping the plugs around and see what happens.

Cheers,

Paul.

Paul van Gool

When the car is running, spray some heavy oil or grease onto the worn throttle shaft and see what it does. This should eliminate some of the air leak. With a 1/16" of play, the front carb should be running rather lean.
Ron Boisvert

Paul,
Over a period of 2 months I tried replacing the plugs, leads, distributor cap, rotor, points and condensor. I also stripped and cleaned the carbs, and checked the fuel pump output. The rear carb has about 5 thou wear on the spindle. At the latter stages, the engine became very difficult to start. Instantly on fitting the new distributor it fired up straight away and held a steady idle. I now have a problem with a stripped thread in a carb, which I need to fix, before I can fully try the new distributor.
Henry

On second thoughts, I think it is possible that the car is running on only one carbie.

Wear on the throttle shaft usually makes them run faster at idle, not miss.

Remove the air cleaner and manifold, start the engine and watch the carbies as you open the throttle. The pistons in the dashpots should both open together. If one is stuck you will soon see it. You should also be able to see fuel being sprayed into the inlet manifold.

Good luck,

Paul.
Paul van Gool

If you think it's the distributor causing #1 & #2 to misfire, rotate the distributor shaft 180 degrees and see if 3 & 4 misfire? (of course you have to change the wire locations as well. I would still bush the throttle body, it needs to be done anyway, it will never run proper with that much of an air leak.

Paul, if the idle should raise if it's running lean, try running lean by shutting off the fuel. It will miss fire as it staves for fuel. With a 1/16" play, you are reducing the amount of flow over the jet to draw fuel into the engine. Once again, eliminate the simple things first, grease around the air leak and see what happens.
Ron Boisvert

J E Logan,

What is the verdict? Did you fix the problem?
Ron Boisvert

Problem still exists, haven't fully attacked it yet. I have rebuilt the front carb throttle shaft, am in process of checking ignition system. Points had deep pitting, coil/condenser/polarity is next step.

Carbs were way out of adjustment, front jet was full "up", rear was 2/3rd's "down". Float settings were off on both and front would flood when any adjustment was made to the jet. Carbs had been re-built (I was told). Engine also was rebuilt so I will do some checking there as well.

I am suspecting also a poor ground to the distributor body also which may disrupt the firing.

I will report back when all is fine.

BTW, this car has had a restoration complete with new wood. It is gorgeous!
J E LOGAN

This thread was discussed between 20/10/2004 and 25/10/2004

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