Street HP 750VS: What would cause the throttle shaft bores to leak fuel?

[MrSinister55]

Hello. The carb in question has already been replaced, but if this is the result of something I did, I'd like to avoid it with my new carb.
The issue was fuel leaking out of the throttle shaft bore (mainly on the passenger side) and a noticeably loose fit of the throttle shaft in the bore itself (I could rattle it back and forth a hair). There was nothing putting and pressure on the throttle shaft and everything moved freely in the linkage. This carb had maybe 5000 miles on it tops, but it did spend a few months in storage off the car right before the problem began.

[Gaz64]

Fuel only leaks out the throttle shafts, if the float levels are too high, and the engine boils the fuel out the boosters on shutdown. "I could rattle it back and forth a hair" is probably a good fit for a Holley, they need to have some movement, otherwise the shafts will bind when the throttle body is over-torqued, as many guys do. Gary

[MrSinister55]

It would only happen with the engine running. I set the floats once and never had to touch them again. I did blow some dirt through the carb at one point, so is it reasonable that maybe the needle & seat were sticking, flooding the bowls, and causing this issue? The rattle in question would produce an audible click when I would move the shaft back & forth.

[Gaz64]

Is this rattle in the shafts up & down, or side to side? Your float levels must be too high, you might need to replace the needle & seats AND the o-rings. Myself, I would rebush the throttle body with bronze bushing, and a vacuum secondary needs to be "loose" on the secondary, free movement versus snug on the primary. But to do this you MUST only have a single thin gasket or a gasket with limiting washers between the carb and the manifold. Gary

[prodart440]

I'm having the same problem, fuel leaking out of the secondary shaft, mainly on the passenger side. It's not boiling over, it will do it if I start the car for less than a minute and let it sit. You can see that the fuel level is at 1/2 way up the sight glass. It goes down from there, not up, and it cannot be boiling. Any suggestions? I've had it apart a couple times. First time the plate screws were loose, so I tightened them and it didn't help. Took it apart again and looked it over really good, and couldn't see anything amiss. Any help is appreciated. Thanks. Aaron.

[Gaz64]

Aaron, if you can see the level dropping, then you must have a visible leak. Can you post a video of this? Gary

[prodart440]

It's not a super fast leak, but within a couple minutes the level is below the sight glass. Where could it be leaking from? It's a brand new carb.

[Gaz64]

What does the engine start like after sitting for this couple of minutes? I've seen this before where the secondary metering plate gaskets are incorrect. Gary