Once you are sure the floats are really floating, look at the needle valves. If they are all metal, make sure there are no apparent contact rings from wear on the needle tips. They need to be smooth. Also, the sides of the needle contact the hole in the seat. Sometimes there are axial burrs on the sides of the needle causing it to stick or not move freely up and down. Those contact surfaces can be touched up a tiny bit with a flat file just enough to let the needle move freely.
Grose jets can have problems, particularly when new. If you have installed them, remove them and wash them thoroughly with carb cleaner. They are typically shipped with a coating to keep the balls from rusting and that can prevent the valve from opening and closing correctly. I have had enough problems with Grose jets that I no longer use them. I use Viton tipped float valves instead.
I have seen a couple of different figures quoted for the float height. I know that the early carbs on my GT6 are set differently than the later CD2 emissions carbs. You may have a float height issue contributing to the leak.
Fuel pressure can be an issue. If you are using the stock mechanical pump you should be OK. If you have converted to an electric pump you need one that operates between 2-3 PSI or you need to fit a good (not flat, round pancake) fuel pressure regulator.
Let us know what you find.
Doug L.
--Previous Message--
: I have a '68 GT6 with dual stromberg 150
: carbs. When I turn the engine over,
: fuel leaks from the mating surface from
: the carb to the intake manifold. I
: have replaced the needle valves with
: new, and have checked the float (it
: floats). Something else must be
: letting the fuel get so high as to run
: out of the venturi of the carb, into
: the intake manifold. Any suggestions?
: Thanks, Mike
:
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