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MG TD TF 1500 - Rich Carbies

Can anyone throw some light on this problem.
I had my Carbies overhauled and any wearing parts were renewed, so it has new Standard (ES)needles and new 90 thou jets. With the jets wound right up, the car runs well. however when the air cleaner is fitted it runs rich and won't run properly past 3500 revs. When on the gas analiser at this point it goes of the dial. I am contemplating fitting (AP)needles which should let it run weaker, unless some one knows of something better to do. Thanks Dave
David Broadbridge

If it runs great without the cleaner, then that is the problem. The air cleaner makes virtually no difference if operating normally. The top of the stock TD oil bath cleaner tends to crush in from years of tightening the wingnut, leaving a very small space for airflow. If so, use a broom handle or whatever and tap it back out. Stuck or sticky carb pistons, defective top jet seals, and dashpot damper tops with vent holes (or plugged up holes) will also do the same thing.
George Butz

Also check the three "feet" on the bottom of the mesh section. They are often bent up which allows the assembly to sit too low and reduces allowed air flow :
Bob Grunau

Agree with both Grunau and Butz on their lists of possibile causes. They are almost certainly RIGHT. One or all of these could cause your problem However, here's another long-shot possibility: Some needles have square "shoulders"--these are to be mounted with the should flush with the bottom surface of the dash-pot piston. Other needles (made by a different process-I think it's on a lathe) have a tapered shoulder, and are to be mounted with the lower end of that taper level with the bottom surface of the piston
Carl Fritz

The Air Cleaner Is a brand new reproduction from N.T.G. in England, and the points you have told me to check are OK,so I have to look elseware.
Dave
David broadbridge

Do the dashport damper tops have holes?
Peter Jengo

Dave,
Does it run fine without the air cleaner? Please be specific about that point. Again, if it does, the problem has got to be in the cleaner or manifold. Just because it is new means absolutely nothing- there could still be a severe restriction. I saw a repro TC air cleaner manifold that when bolted to the carb the manifold to carb hole was off so far it covered 1/3 of the carb opening! George
George Butz

Correction/clarification to typo in my first post- TC/TD carbs must have damper top holes, TF carbs do not.
George Butz

What altitude is the car usually working at ?

Have you tried other type of air filter, just as the repro type used on TF's?

Are you sure the car works 100% up to 5000 rpm without the air filters ?

How many turn are you giving to the jet adjusting nut ? If you say it has no turns as implied in your first message maybe the carbs are wrongfully assembled.

have you tried lowering or basically playing with the needles ?

I had my original TD air filter removed and put a set of air filters as on the TF and the result was a very good improvement of the car. I now run it with TF filters and I m very happy.

I agree with George Butz on the problems with the TD air manifold.
Jose Vargas

I had a similar problem and I put EW needles, that cured it totally. Now the jets are two turns (turns, not flats) down where it runs neither rich nor lean.
Denis L. Baggi

Futher to my carbie problem, I went for a run on Sunday, with my "BREWSTER" air cleaner fitted ( which has no filtering element at the moment, it would be good for keeping out stones). With this fitted the car ran well, however when I got back, I checked the spark plugs and found them to be black and sooty as was the exhaust.So I still think I will have to look into experimenting with the needles, I will have a look at the EW needles that Denis mentioned.
Dave
David Broadbridge

I wish to report a good outcome re my carbie problem.I took the advice from Denis of Switzerland and bought and fitted some EW needles.The car now runs like a top with the proper aircleaner fitted. I had the car on the rolling road today with the gas analiser hooked up and the tuner said the mixture is as good as we are likely to get.So thanks very Denis.
Regards Dave
David Broadbridge

Actually I should not take the total credit for that, I called up Burlen Fuels and asked for needles to make the mixture leaner, I bought EU and EW and was happy with the latter.

Denis
Denis L. Baggi

This thread was discussed between 11/03/2000 and 26/03/2000

MG TD TF 1500 index

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