2200TC overrunning

J

John Skittles

New Member
To cure many problems,one of which was serious overrunning, I've just had my 2200TC given a full tune up by Southern Carburettors of Wimbledon, and the only way they could get rid of the overrun was to adjust the idle to the point of almost stalling (not sure exactly what rpm as my tach is out)and then recommend depressing the clutch to put some load on the engine before switching off. They also said '...some engines do that.' If I bring idle up to a more acceptable level, the overrun comes back.

Does anyone have any comments or suggestions?
 
For the engine to run on something other than the spark plug is igniting the fuel and this will tend to be heavy carbon deposits glowing red hot when the engine is run.

Other possibilities are an incorrect grade of spark plug so that the tip is overheating and igniting the fuel/air mixture.

A weak mixture may also cause the engine to run hotter than intended so something in the combustion chamber is hot enough to ignite the fuel.

It seems wrong in my opinion to say that some engines do that but it may be true to say that some high mileage engines tend to suffer from running on.

Maybe a decoke is in order.
 
Having been in the service business for over 30 years I will suggest that words like "some engines do that" ,and "that is normal" can be translated as "we don't really know"
Many years ago I was told "that is normal" when my Austin was backfiring .....gulp valves (an emission control) was the real cause.
No engine is meant to backfire or run on. Something is amiss.
Dick West
 
In fairness, they did also mention that hot carbon deposits could be a cause. However, the engine was purchased as a recon unit, to which end I would like to think it had either new, or at least decoked pistons. That said, I haven't removed the head to check and only have the word of the guy I bought it off that it really has been reconditioned.

Therefore, maybe a decoke could be required, but to follow up BB's other point, what are the best spark plugs for the job? I'm currently running with Bosch plugs (don't have type number to hand as I write this though), should I switch to Champion?
 
I wouldn't imagine the wrong brand would cause a problem they just need to be the correct heat grade. Heat grade refers to the length of the ceramic insulator around the electrode, the longer it is the hotter it will run as it is less able to conduct heat away and more surface area is exposed to the combustion chamber.

As long as you are using a correct equivalent it should be OK or though you could try one grade colder if you are also having problems with pre-ignition.

Would have expected them to have changed the plugs as part of a tune up and used the correct type.
 
Strangely, they changed just one spark plug (no.2) and I had to replace that this weekend as I noticed that the HT end electrode was damaged on it.

Anyway, I think I'll check exactly what I've got and replace all if necessary.

Many thanks for all the advice.

John
 
Assuming you are running unleaded, this does burn slightly hotter, so a one step in spark plug grade might be worth a try.

The adverse effect can be difficult starting as the plugs don't get hot enough to burn off any deposits.

Also slightly retarding the timing can help to keep the chambers cooler.

I have a 2.2TC and it too runs on quite badly, and was no different after I removed the head and de-coked it. I haven't tried different plugs though.

So I suggest you try all the external (read cheap) possibilities before opening the engine up.

Richard
 
Another possibility, which hasn't been mentioned here, is a vacuum leak.This would make sense in terms of the inability to get a good carb adjustment.Take a good look at the carbs and manifold.
Dick West
 
It was letting air in at the manifold, but I sorted that before taking it for the tune-up. I'll spray some WD40 around the carb mounts though and see if it comes out through the exhaust.

As for petrol, I am running on unleaded (Shell Optimax or BP Ultimate) so will consider the plug temp grade, although I would be concerned about difficult starting, especially at the moment with the cold weather as I'm already having trouble getting it going - hopefully the new distributor cap that should arrive tomorrow will help there too.

Another theory that's been proposed by a work colleague is that the timing chain could have been put onto the camshaft sproket a notch or two out during the rebuild which could be causing difficulty getting the timing accurate.
 
My 2200TC used to run on but doesn't now (I don't know why) but my 2000TC runs on pretty badly. I switch off while in gear then lift the clutch. I'm going to rebuild the 2.2 soon anyway & I'm gradually enriching the mixture on the 2000 to try & remedy it as I think it is running weak. We'll see!
As to rebuilt engines, if everything happened as we like to think, we'd have no maintenance to do on any cars we owned, which could be a good or bad thing depending on your point of view.
 
You must log in or register to reply here.
Back
Top