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MG TD TF 1500 - Fuel Level Question for Dave Braun

Hi Dave,

I am using your nice technical article to set the fuel levels and jet levels on the TD carbs.

The fuel level in the jet is stated as being 0.160 plus/minus 0.040.

The rounded end of my float valve fork is bent so that it is basically even with the flat arm of the fork - and my fuel level is still well below the range listed.

Everything is clean and the valve is not sticking.

Any thoughts on possible problem areas?


Thanks in advance.

I also wondered if you had a preference level from within the range listed - should E10 fuels be set at a certain level?

DLD

Your floats must really be light to float that high! Just kidding.

It can be very difficult to measure the fuel height by dropping the jet with the enrichment lever. The amount of venting in the float lid and the small diameter of the jet makes the capillary action more pronounced. Patience helps, as does gently tapping the bowl. Also, remove any washers/spacers that may have been placed under the float needle housing. Make sure that the straight portion of your float lever is straight, not bent or kinked. Make sure the segmented washer at the top of the float bowl lid is allowing venting into the vent pipe, and the vent pipe banjo is right side up (large diameter opening towards the segmented washer.)

The preferred height with current fuels is closer to the .200 number, but lower works if both are approximately the same.

Hope this helps,
Dave
Dave Braun

Hi Dave,

Thanks so much for the quick and thoughtful response.

The vent on the bowl dome is clear and open with the proper vent washer and overflow pipe orientation. The lever itself is flat from the hinge pin area to the curved finger portion.

There are no washers under the needle seat valve. I will keep working with it and see if I can bring it up to the .200 setting. Very odd situation - the float sits well down in the fuel - the top surface is just a little above the fuel level - but the float is not full of fuel - completely dry.

Stay tuned.

Thanks again
DLD

Is it possible that someone has tried to repair a leaky float and added much too much solder. This increased weight may be your p[roblem.
Sandy
ss sanders

That is weird. When the float is sitting well down in the fuel, and the fork almost flat, I would expect the fuel level in the jet to be too high. The higher in the fuel the float sits, the lower the fuel level, and you are reporting a low fuel level, right?

You need heavier floats or less dense fuel.???

You're sure you aren't suffering from capillary response when measuring the depth?
Dave Braun

Dave is correct.
Have you checked the gasket between the float chamber and carb body. A too thick gasket will also give you a false low fuel symptom.
Sandy
ss sanders

Hi Dave - I am clearing the jet of any capillary fuel with a q tip and a bent paper clip - to ensure that I am not getting an inaccurate read. It is odd as you say.

I will pull the jet bearing assembly and make sure all is ok - I have used Mr. Norby's teflon o-rings and they are leaking quite a bit - so I will replace those with the oil-soaked cork and try again.

Very puzzling situation .....
DLD

Could you post a picture of the connection of the float bowl to the carburetor body?
Dave Braun

There should be one thin fiber washer between the float bowl and carb body. What brought about adjusting the level? Did you just rebuild the carbs or something? Is the hole in the lever arm hogged out? New lever arms or float needle assemblies could be mis-machined? Since the mid-70s, I have always used the "factory" method of the 3/8ths or 7/16" from the float lever to the lid edge with perfect running, plug color, etc. Maybe not as precise, but has always worked perfectly for me. Lastly, if all assembled correctly, pretty much impossible for the Teflon O-rings to leak. I have seen the top brass washer (I think) that is too thick in some kits that keep things from seating/sealing properly. George
George Butz

George is basically correct regarding washers, except that many H Series have been converted to the rubber washers which require a longer and slightly different banjo bolt from an MGA or Magnette. This sometimes can cause a low fuel level. You can't use the fiber washers with the rubber washer banjo bolt, and vice versa.

Warmly,
dave

Dave Braun

This thread was discussed between 07/06/2014 and 08/06/2014

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