billmoore42 wrote:My biggest nightmare. I check my carb fuel lines regularly, but am always worried that the Webers often have a bit of fuel residue under the misab washers after a run. I have been told this residue is normal, and to expect a bit of 'fuel varnish' to accumulate under the flexible washers. Maybe time to get two fire extinguishers, one under the seat and another in the trunk!
Just catching up with this thread - somehow missed it before.
I worried about wetness under Weber misab plates/ flexible mounts for years and was also told that it's normal. OK, so it may be very common but, nevertheless, it can't be right.
The flexible mounts (put together properly, of course) do not leak. Presumably, if the mounting were indeed faulty the vacuum in the inlet tract would result in minimal leakage and, anyway, the air leak would cause the engine to run/idle poorly.
So I'm of the opinion that the fuel that collects under the flexible mounts has leaked out of the accelerator pump chamber and/or the starter circuit air intake. As a result I've put some effort into ensuring that the pump chamber doesn't accumulate fuel (by drilling a vacuum releasing hole in the cover plate, copying late model Webers) and adjusting the float valve to ensure that the fuel chamber level is not too high.
The net result is that the flexible mounts are dry, 99% of the time. Very occasionally there's a slight smear of dampness which I put down to a rare fuel slop out of the starter circuit. I can live with this. I imagine for racers the best approach would be to remove and seal off the starter circuit (and, as we know, there are kits to do this).
I've no idea what the fuel level is in the jets but the engine runs very well and doesn't stumble, so I guess it's about right. And hopefully I've reduced the risk of fire.
I happen to have a braided fuel line because that's what Ray sells. I keep a close eye on it, and would do the same if it were not braided.
Excellent tip earlier about being sure to know how the fire extinguisher works. I need to re-read the instructions on mine!