TR2/3/3A Leaky SUs - Late TR3A

[jsneddon]

So I rebuilt the carbs about 6 months ago with new gaskets from Moss. Granted the car isn't getting much use but it was dry 2 weeks ago and now today it took a long time to fill up the floats and I have a steady drip from both carbs.

They are leaking from the spot where the floats attatch to the carb body from around the "Grommet, float bowl mounting"
The jet assy. is dry so I don't think the cheesy cork o-rings have given out yet.

#118 here:

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29127

So. Another 4 bucks for some new grommets isn't going to kill me. But is there any improvement to these little gems?

Did I crank them down too hard? I don't think so because I distinctly remember being gentle with them and they leaked right away until I cranked them up a little more. At this point I've got nothing to lose by tightening them up a little more but I seem to be into the realm of deforming the rubber.

A slightly stiffer material that is less prone to deforming would sure be nice.

 

[sp53]

Hi Jim yes those can be tricky and problematic. What type mounting bowls you have also makes a difference, the earlier ones leaked worse. Sometimes the metal washers are not thick enough and you run out of threads on the shaft before the rubber has a chance to seal. If that is not the source of the leak the bowls do have tendency to vibrate loose. The early cars had a brace that ran from the top of the float bowl to the section chamber. I think that Moss still shows a picture of it#(133), but they are no longer available. What I did was to make a couple out of flat stainless sheet metal and that solved the problem.
George

 

[jsneddon]

I assume you are speaking of #62 on Plate G of the factory parts manual. Interesting idea. I might just give it a try. I've never seen any kind of support like that on SU's on any car - I kind of like it. I can't imagine that once the rubber is cranked down you are getting that much vibration isolation to the float chambers anyway.

 

[sp53]

Yes that is it. If you notice that is an H4 carb and they had the banjo fittings like the early H6. Perhaps it is the weight of the banjo and braded hose that caused the problem. At any rate, when they switched to the rubber fuel line, I believe that the brace went also. In addition, when they switch they also changed the bolt fitting to a stud fitting for the fuel up take and this perhaps eased some of the vibration.
George