Bergerboy

Hi Folks,
Can anyone pinpoint a root cause for why I should get a slow drip of fuel coming from the area of the secondary bowl, circled in the picture?
Seems to occur mainly on startup, which may indicate a flooding condition, but why at the secondaries? They don't kick in until under load and WOT.
Seems to be a breather of some kind, as it looks like a screen insert where the fuel is seeping from.
I don't get the leak when the engine is off, and there doesn't seem to be any accumulation on the intake surface to indicate it's a continual lead while driving.
Just a nagging issue that I'd like to try to address.
I'm tackling all the issues that prevent me from keeping a clean engine compartment, and this is one of the remaining ones.
Thanks,

TimAT

That is a pressed in plug, installed after machining the float bowl. The small tube is a transfer line from the fuel inlet to the rear bowl. There is a small o-ring on it that may be the real source of your leak.

7T1vette

You could TRY using a flat or rounded-tip drift to rap on that 'plug' in an attempt to stop the leaking. Otherwise, you will need to purchase another rear float bowl.

If the seal is damaged (inside), attempting a fix will be of no consequence; you will still need to replace the bowl if unsuccessful. But, if the plug has just loosened, you might be able to tighten it up by giving it a little 'shot' with a hammer and drift.

Bergerboy

Thanks 7T1.
So are you suggesting tapping on the "face" of that plug, directing the force inwards?
Or wrapping on the outer radius of the barrel fitting?
I thought that plug was a screen or porous stone type of breather or filter, not just a dead plug.
What is the seal in detail? Is there an O-ring behind there? or some sealant of some kind?
Thanks

Haggisbash

The seal is a press fit I believe same as a core plug or frost plug in your engine block, someone will correct me if I'm wrong, I don't think there is a seal behind there. The silver transfer pipe that goes between the fuel bowls does have seals on it as TimAT has said and this could be the real source of the leak. If it is the blanking plug that leaks tapping on it could fix it or just as easily make it worse JMPO.
You could bubba it as a temp fix by filling the edge between the plug and the fuel bowl with a fuel resistant epoxy like JB weld.
Its doubtful you have a flooding condition if the car is starting and running normally, a quick check is to watch the boosters (the circular things suspended over each intake throat) and see if any fuel is going into the engine from these at idle. No fuel should flow from these until the throttle is well open.

Bergerboy

Pretty sure it's not flooding the secondaries, as I previously verified they are bone dry at startup, idle, and even going WOT when standing still. Just not sure how the fuel flow is supposed to operate in those conditions, in the pipeline between that silver transfer pipe, the 90 degree fitting with the plug seal, and into the rear bowl.
Is my leaky seal an indication that the rear bowl is overfull, and that leak is run-off from that? And if so, is that a problem in itself?

Raphiki

Looks like the problem is the seal itself. There is pressure in the cross tube and, with the inlet valve to the secondaries closed, the fuel can't enter the float bowl. If that seal is bad it will leak out there. The float bowl in not being over filled or it would either come out the breather at the top or would flood the engine.

TimAT

That silver transfer tube is under pressure- it's the same as the fuel inlet on the other end of the carb. That tube is what supplies fuel to the secondary side of the carb. I've never seen that plug leak, (not saying it can't), but I have seen that transfer tube leak at one or both ends. Before you get too busy, I'd get a couple of float bowl gaskets and some O-rings and replace those first.
You asked if the bowl was overfull- if it was, it would drip into the carb throat before it comes out there. As Raphiki stated, it will drip off the venturis in the center of the carb- and you would know it. It would be stinking rich, and act flooded all the time.

terrys6t8roadster

Mine was leaking from the top plug, I used some JB Weld to seal it up two years ago and still dry. T

Bergerboy

Thanks all!
Looks like I nailed it last night.
Took some of the 2-part "steel dough" type sealer and - after kneading it together - pressed a wad into each of the seal faces (side and top).
Let it cure for an hour, and started up the engine.
I detected a very slight weeping of fuel from the top plug's seal, but nothing from the side plug, which was the bigger problem area.
Let it idle for a while, revving the engine by hand, and the weeping never got to the point of accumulating or wanting to drip at all.
Buttoned up the air cleaner and took her out for about a 30 mile drive.
Came home and checked the top of the intake manifold - and she was bone dry!!
So, that fix, together with the prior advice on sealing up the intake manifold bolts with a bit of pipe thread sealant, and now I've got a nice clean top deck!
Thanks again for all the expert advice offered here!
Now on to that nagging oil drip on the garage floor.
Looks like I've got some time on my back this weekend, replacing the rear main seal and the oil pan!
Have a great weekend one and all!

doorgunner

Thanks for the update!

Randy G.

I Hope I'm not too late to the discussion here. The dime sizes core plugs are notorious for leaking. The common fix is either JB Weld or buying a new float bowl from Holley through Summit.

People who have used JB Weld have reported years of service with no problems. I bring this up because I soaked my Holley off my '67 Corvette today, reassembled it and now it seeps fuel at the front float bowl at the plug. I may try to just make a pretty thing smear or bead in the corner edge all the way around with JB Weld and run it. The air cleaner hides it anyway.