Holley 3811 secondary flooding with car nose up

[William F.]

Thought I had this problem licked but not so. My 3811 on my '67 L36 floods from the secondary boosters only when the nose of the car is elevated, such as on ramps for oil change or after parking with front higher than rear. Dripping does continue for some time after car is leveled. Had to drain fuel from secondary bowl by loosening a lower bowl screw to make it stop today. After restarting on level ground, no more flooding. this is not a heat soak problem. Have checked for hole in float, replaced needle and seat and lowered float level somewhat but problem persists. What do you think? Something binding float or needle at angle to seat when car is in nose up position?
Thanks

[Stephen L.]

Re: Holey 3811 secondary flooding with car nose up

Had a similar problem on my 3811 this past fall. The secondary bowl would leak onto the manifold. After attacking the float, needle, seat etc. I discovered that the aluminum plug on top of the bowl was leaking. This is ahead of the needle in the "piping passages" so the float etc. did not have any affect on this. I fixed the leak with a thin coat of JB weld on top of the plug and a "slight" spray of paint to give it the original color. These plugs are not in any kits.

[William F.]

Re: Holey 3811 secondary flooding with car nose up

You put it on the top-outside of plug, bowl, not inside, right? Haven't heard this problem-the leaking into the bowl but who knows. Still don't see how this would leak ONLY when car is parked with nose high.

[Timothy B.]

Re: Holey 3811 secondary flooding with car nose up

William,

There is a spill distance from the bowl float level to the nozzle and when you raise the car the float level is changing because the needle is opening allowing additional fuel into the secondary bowl. You may not have a problem, try to lower the float a little more to increase the spill distance.

[Stephen L.]

Re: Holley 3811 secondary flooding with car nose up

William, my "leak" was external and the plug is on top. I had never experienced this particular type of leak before.......it showed up as "fuel puddling on the intake"........... like the carb was overflowing into the engine and coming out of the throttle shaft.

[William F.]

Re: Holey 3811 secondary flooding with car nose up

Tim, I appreciate your answer, but if this was the case, wouldn't you have flooding every time you went up a hill? Guess you're saying this happens only if the float level is too high, though, right? I'll recheck float level but still have to wonder if the float or its mechanism or needle is/are hanging on something keeping needle from seating.

[Timothy B.]

Re: Holey 3811 secondary flooding with car nose up

William,

It's possible the float could hang up, but as a test put some water in a coffee cup and tilt it back. You can see how the fluid stays level but the float changes position because it's fixed to the carburetor bowl. IMO, that may allow some additional fuel inside causing what you are seeing.

If the car runs normal other than that I would start with the simple stuff. I am not 100% so double check but the factory float level on the secondary is lower than the primary bowl.

[William F.]

Re: Holley 3811 secondary flooding with car nose up

I always like to give a followup. Removed secondary bowl, float, and needle/seat. Shook the float and it had gas in it and was sinking as my flooding problem Thought I'd checked this before, but maybe not. Apparently pin hole leak, probably due to poor factory solder job of joining the 2 halves of the brass float together.