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SU Carbs

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WJM

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I have a problem with my SU Carbs. The dash pot keeps leaking the oil. It must be going into the manifold as there is no sign of it any where else. Is there a seal on the dash pots to stop this. Regards John.
 
My 1968 B needed them filled every 500 to 1,000 miles - if I didn't (and didn't balance the carbs every 1,000 miles) there was a dramatic performance decrease. I refill them on my B-GT at every fillup at the gas station (I carry a little in a squeeze bottle) and don't have any problems at all.
 
Help me here... is it even possible for that oil to leak? I mean is there any where for it to go? My recollection of the chamber for the damper is that it is solid metal... no seals or holes down at the bottom.

Sometimes we overfill the damper chamber and the excess gets pushed out, so it looks like it has leaked down. I think you only need enough to provide resistance for the last quarter inch of piston travel as you push in the damper to close them up.
 
As I recall, you only fill them up to within 1/2" of the inner rim (just below the bottom of the threads). I've never seen any leakage on mine and presume that it must get sucked away during acceleration (since that's the problem that occurs when they're dry).
 
In answer to your original question, there are small O rings on the ZS carburetor dash pots. There might be some small seals on some model SUs but I am not sure. Take your dash pot piston off the carbuetor, fill it with oil )(better still, low viscosity liquid like solvent) and see if yours leaks. If it does, go after the seal.
 
Hello WJM,
there are no seals on S.U. carburettor dashpots. The oil only needs to be in the inner (piston tube). If you add too much oil it gets pushed out the little vent hole in the damper lid.
There is sufficient oil in it iff you can feel resistance when you unscrew the damper, remove it then push it back in.

Alec
 
Mine goes away in time also. Just put more in there to the ridge below the threads and don't worry about it.
Bob
 
[ QUOTE ]
Mine goes away in time also. Just put more in there to the ridge below the threads and don't worry about it.

HI Bob, /ubbthreads/images/graemlins/lol.gif Filling the inner tube to witin 1/2" of its top, as mentioned by others, is the accepted method of servicing the SU dash pot.-Merry Christmas---Keoke
 
Thank you all for replys. I though it had to be filled DOH made another blue but you learn for mistakes. Once again thank you. Kind regards John.
 
[ QUOTE ]
Help me here... is it even possible for that oil to leak? I mean is there any where for it to go? My recollection of the chamber for the damper is that it is solid metal... no seals or holes down at the bottom.


[/ QUOTE ]
Hi Geo,
The later type SU's, the ones with spring biased needles, have a small sheetmetal plug between the damper chamber & the needle holder. The inner bore of the piston is bored straight through & then plugged. This plug is not shown in any parts books or manuals that I have found, but it's there. It could be possible for this plug to get dislodged or to leak a bit. Maybe the source of mysterious oil loss on SU dampers?
D
 
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