I have a set of original H8 carburetors on my XK 140. I have seen various suggestions for setting the float level, including 5/8", 3/4" and one inch. The float bowls are quite large on these carbs, but the issue is getting the fuel level low enough in the float chamber that it does not flow out the jet flooding the throttle body. I found that one inch worked in one carb, but not the other (the front one if that matters). Anything less than one inch leave the fuel level in the float chamber higher than the jet. Anything beyond one inch submerges the float without changing the volume of fuel displaced, or the fuel level at the jet. The floats are the original brass in good condition.
I am not an engineer, only the son of one, but I suspect many of you are. My uneducated guess is that a fix would be to find a more buoyant float, or one that is taller. As it is, the float only sits proud of the fuel by at most 1/4 of an inch with no load on it. With the cover and fork installed I suspect it is no more than 3/16". As a result, the window of adjustment is very narrow. One inch is also an extreme adjustment for the float fork, creating significant angles which may impair its operation. A more buoyant or taller float could help correct this, but no one seems to make one. Another possibility would be to lower the entire float bowl compared to the throttle body and the jet, but I am hesitant to pull everything apart and start screwing with the original design.
The common lament is that float levels on H8s are a bitch to set, and simply a downside of owning these rare carburetors. But, I need to solve the problem since I have fuel leaking out the front jet no matter what I try. Any suggestions?