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MG MGA - Sticking Jets w/ teflon seals


I have just recently rebuilt my standard SU's for a 1600 engine (at least, that's what the engine ID plate indicates) although it's a '59A. I used the teflon seals per Barney. Even after "pumping" the jets up and down well over 20 times (more like 40-60), the jets (both)still stick down about 3/16 to 1/4 inch when choked and have to be manually returned to their bottomed (up) position.

I have ordered new choke return springs on the off chance that the old ones have lost some tension. All other parts are new (items that come in the rebuild kit from Moss), including the choke levers.

The jet bearings have been centered using the centering piece from the SU took kit. Pistons and needles fall freely (although it took quite a bit of force to get the rear carb jet bearing centered).

Does anyone have any suggestions? I am considering putting 1500 needles in it which will require that the jets be adjusted downward thereby helping to get out of part of the sticky "territory".

Is there anything I'm overlooking?

Many thanks!
JM Morris

I had trouble with sticking also. I'm not sure if they were teflon seals; they weren't cork, they may have been neoprene or viton. Anyway, I bought springs from the local hardware that were basically identical to the original springs. I then shortened these springs till the sticking was eliminated. It makes it a bit of a tougher pull on the choke cable, but no other effect. One good thing, they don't leak a drop. The original springs are kind of weak at their last bit of pull, and even a minute amount stuck will cause rich running.

Ralph
Ralph



Thanks, Ralph. I assume you cut and rebent the ends of the springs?
JM Morris


I just replaced the old springs with new ones, but still have the stiction problem. But for future reference, the new springs are exactly 7/8ths inch long (measured from the top of the top coil to the bottom of the bottom coil). The old springs had stretched to 15/16ths inch.
You could feel the difference in the pressure it took to stretch old vs new.

I've also replaced the old choke cable with a new one, which doesn't appear to be nearly as well built as the old (apparently original) one. The new one doesn't want to hold the choked position. May try to refurbish the old one.
JM Morris

This thread was discussed between 14/05/2010 and 16/05/2010

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