Hello all,
I've got a 71 4 banger with dual weber idf 44's on it and the driver's side front barrel has sprung a leak.
Here is a little detail before I go further into the leak:
The webers are about 6 years old and have about 7,000 miles on them. The car sat in storage for about 3 years but was started and driven every 6 months or so. For all I know this leak has been there all along and I never noticed, but I don't think that is the case.

The leak:
The carb is leaking gas down the front barrel on the drivers side. It appears to be coming from the progression / transition holes but it is hard to tell. The other thing I noticed is that the gasket just above the float bowl is very wet and the gasket between the carb/manifold is also a little wet. I have been dealing with this for about 2 weeks now and have read every possible thing I can find and none have solved this.

Here is what I have done so far:
-Float set at 10.5mm measuring with the gasket in place.
-Butterfly was loosened and repositioned in the bore.
-Needle and seat have been tested both with fuel and air and are good
-float is free in movement and does not hang up in the bowl
-float is still a float and does not sink
-idle circuit is free flowing and not clogged
-fuel pressure is 2.5
-float bowl gasket does not accidentally cover any holes or vents


Any ideas on this one? I feel like I have tried everything and for the life of me I can't figure it out. Last night I was watching the fuel puddle on top of the butterfly and it seemed like maybe it was coming from the seam at the float bowl gasket. Any reason why fuel would be coming from there?

As FYI:
This happens when the car is hot or cold, doesn't matter.

can you see a dribble when the fuel pump is energized and engine not running?

It isn't a constant dribble from what I can tell. If it is it is very hard to see. It will do it when the fuel pump is off or on, doesn't matter. It doesn't appear to do it when the motor is running but I have only spent about 5 seconds checking it with the motor on.
I can hear the carb make a gurgling noise once every 30 to 60 seconds as well.

If it's leaking from a press in plug in the body clean and sand it good and use epoxy or JB Weld.
If it leaking/overflowing from the floats you need a good pressuure regulator. The little chrome regs are pure shit and the Holley doesn't go low enough.
Most pumps, even so called low pressure pumps are crap at maintaining low pressure these days.

Hands down best low pressure regulator is a Malpassi.

It doesn't appear to be a press plug. This is leaking inside the carb and down into the motor. Could a plug cause that?

With regards to the regulator, I see a lot of people have these holley ones. I was able to get mine down below 2 psi yesterday actually. I have not seem anything above 3 psi after I set it though. I don't think 3 psi could cause this if the needle and seat are good and the float is good and the pump isn't even on.

Leaking inside the carb is you have a fuel enrichment circuit stuck open.

It's the little lever on the side of the carb that is not used/hooked up. It may have been replaced with a plate with 2 screws.
The plungers inside one (or more) is cracked open. In fact I have tapped, plugged and permanently disabled these plungers before.

3-3.5psi is what you want.

Well...this is one area I have not checked yet. How do I go about this? Just open the side plate and clean and check everything?

Also, would this cause fuel to leak out of/onto the float bowl gasket?

With Mark.

If one of the circuits is stuck open, it can DUMP fuel into the cylinder(s) and into the engine really quick. Do not run it like that if you can avoid it.

If that is the case, the easiest way to fix it is with the carburetor off of the engine. You may get lucky and get it to unstick by actuating the lever that Mark pointed to in the diagram, but you might also end up sticking up the other enrichment valve. Again, better to pull the carb off and then remove the carb top to inspect and/or plug the circuits.

Interestingly, I have not yet seen a Weber 44 with enrichment circuits - only on 40s. If it's got the lever on the side of the carb top, it almost definitely means that the carb has the circuits though.

Mine does not have a lever, just a little block off plate with the weber logo.
Not sure if that changes things...

The only way i know to verify if the carb has patent enrichment circuits is to remove it, and the carb top. There will be two recesses behind that block off plate. Each holds a valve assembly, assuming that the carb body was drilled for them from the factory.

As Mark said, someone could have removed the lever assemblies but kept the valves in place (and put the blockoff plate in place of the lever), hoping that they would stay seated and not open. But they're only held shut by a very thin spring and often they do indeed pop open. You might have enough room to pull just the blockoff plate off and see if there are two brass valve assemblies inside that recess. But it would be easier to take the carb off again IMHO.

The float bowl gasket is in contact with fuel - it does get wet.

Even without the entire enrichment assembly there are spring loaded pistons inside the carb which can become dislodged, move into a stuck open position, and allow fuel to leak through that circuit.
Take off the top plate and check the pressed in washers that retain the spring/piston assy.
Also remove the side cover and make sure the pistons are in their closed position.

I have had 44idf's on my car for 10 years and have had great use out of these. http://www.cbperformance.com/ProductDetail...roductCode=3193

Got it, I'll take it apart this afternoon and make sure everything is working right.


On a side note:
If gas was leaking from float bowl gasket down into the barely what would that indicate?
I swear I saw a little gas run down the side of the barely and it came from that seam where the gasket is and it was on the opposite side of the float bowl (hope that makes sense)

Barrel*....damn autocorrect

Sorry, I should have been more specific. The valves/pistons inside the body that Chris is referring to are part of the entire enrichment circuit. The levers on the outside were there just to actuate the pistons to provide a function similar to a choke when the engine is cold. The problematic parts, as Chris described are the pistons and springs though.

If you are confused where they're housed, there are pictures in my carb rebuild thread:

http://www.914world.com/bbs2/index.php?showtopic=207017

Same applies to 40s and 44s. Though like I said, I haven't seen 44s with patent enrichment circuits yet.

The leaking from the bowl into the barrel could theoretically be from either a gasket that is pinched, or even a carb top that isn't true anymore. If you have a piece of glass you can set the carb body and the top on it to check for trueness or use a straightedge.

If leaking/spilling over the float bowl you more likely have a a float level or fuel pressure issue

Well,
It wasn't the choke pieces, the plungers weren't even there.

Would bad gaskets cause something like this?

How new are these carbs? Do you have a pic of one of them, preferably from the float bowl side?

Jake,
Carbs were purchased new about 6 years ago.
I don't have a photo on me but I will snap some pics for you this afternoon.

Gaskets should be changed every time you crack the top. Fuel sloshing around in the float bowl could leak around a bad gasket or a warped top.





You thinking inferior casting?

There are a lot of variables, not to mention good advice from others. So I think I'll shut my mouth after this so as not to add too many voices here to confuse you.

Like Jake said, it would be nice to see pics of the offending carb.

Mark makes a good point too - if fuel is bubbling up over the bowl and into the TB, then you have an issue with the float, and possibly with the gasket too. At this point you've taken them apart enough (and they're six years old) that it's probably time to go ahead and replace the gasket anyway.

What kind of linkage do you have on the carbs currently? Positive that it's synched correctly? A throttle being held slightly open can allow the accel pumps to dribble fuel (not sure if you've verified for sure that it's not actually coming from the pump jet).

So it sounds like the gaskets aren't the issue despite needing to be replaced. This happens when the car is off so no fuel pump going.

Just a quick update to all:
Last night I lowered the fuel pressure a tiny bit and also set the float height to a little lower (more like 12mm with the gasket in place now) just to see what would happen. Took it for a spin and came back. When I got back I didn't hear anything immediately but I didn't take the filter off to visibly check either. I cracked the throttle by hand however and let it close and after doing so the carb began to gurgle so apparently neither of my changes made a difference.

So it sounds like the gaskets aren't the issue despite needing to be replaced. This happens when the car is off so no fuel pump going.

Just a quick update to all:
Last night I lowered the fuel pressure a tiny bit and also set the float height to a little lower (more like 12mm with the gasket in place now) just to see what would happen. Took it for a spin and came back. When I got back I didn't hear anything immediately but I didn't take the filter off to visibly check either. I cracked the throttle by hand however and let it close and after doing so the carb began to gurgle so apparently neither of my changes made a difference.

Do you have thick manifold to head spacers?

Sounds like they are getting heat soaked. Heat from head transfers to carb. Boils the fuel. Carb gurgles. Bubbles form in idle circuit. Since drilled passage is small the bubbles carry fuel through the circuit and you see it weep out of the progression ports.

I considered that. I do not have the phenolic spacers so that might be part of this. Problem is the carb is leaking when the motor is cold too so I'm not too sure if these spacers are the final answer.

The carb bubbling and gurgling after running sounds like textbook heat soak.

Without a stuck float or bad inlet needle valve or seat, fuel "shouldn't" get as high as the top gasket. You'd also see it dump out of the aux vents. It's pretty easy to spot. It "should" only get as high as your preset float level. The idle circuit is drilled higher but requires vacuum to pull it up. The accelerator pump circuit is drilled higher but requires pump actuation.

I'm at a loss. Need pictures with leakage area circled.

I've heard about inferior/flawed castings. I believe they're out there but I've only seen slightly mis-drilled butterfly shafts.

did you test the floats in a cup of water when you had them apart...
any chance you could have a bad float?

Again, I agree. At this point we can't offer much more help till you take pictures.

You told us that the car had been running and driving fine, but all of a sudden this issue arose. So there is nothing mechanically that changed to be the source of the problem. Which means something plan ol' wore out. Keep in mind that the carbs are now six years old. Even if you've set the floats correctly, the needle valves are likely brittle and could be the source of your leak, even with the engine off. The heat soak is likely exacerbating the problem. Seals, gaskets, etc in carbs have a shelf life, like everything else. Ethanol in fuel has reduced that shelf life some as well.

The fix: rebuild the carbs or at minimum install new needles and seats. You have removed the tops enough now that the gaskets are toast, as others have told you.

While the carbs are being rebuilt, consider installing the phenolic spacers between the head and the intake to get rid of the heat soak.

Edit: I like Brant's suggestion too, if nothing else for piece of mind.

Ding, ding, ding. The plungers need to be in place or plugged. If not that is your issue. Even if one chooses to not use the enrichment circuits they still need to be in place or plugged...one or the other. Which is it? Post a photo of the circuits.

They make IDFs without the enrichment circuit machined. You won't see plungers or plugs. Remove the block off plate and there's nothing behind it but bare casting.

Are you sure they are Webers? About 6 years ago "EMPI" started importing Webers made in China. The first couple of batches were porous . I had a 914 owner come to me about a year ago and the Chinese carbs and manifolds were stained with fuel that was not comming from any place where there was a casket or plug. He called EMPI and the told him they had a past history of carbs that leaked through the castings.

This might be a long shot, but dont carbs need a vent out the top to equalize pressure with the atmosphere or pressure will build in the float bowl?

Any chance the OPs bowls arent venting properly?

Wrong gaskets, backwards, air filter bracket blocking, etc?
The gurgling and spitting is a clue.

Ok guys I finally got around to the carbs again and I removed the carb from the car to install phenolic spacers and here is what I found:
Without being on the car, I can't get the carb to leak on top of the butterfly. However, the same barrel that I have been having issues with all along will leak fuel from the mixture screw hole under the butterfly. I had to coax it to leak (move carb a bit or shake it or tilt it) but it would leak. I couldn't get it to leak if I turned the screw in all the way. Yes the screw does have an o-ring on it as well as the spring. If I tilt the carb backwards a little fuel will drop from the outside of the screw (where you adjust it by hand or via flathead screwdriver)

Obviously the carb isn't tilted when it's in the car, the above is just what I observed. I put in a new float, mixture screw, mixture screw I-ring, and mixture screw spring as well as all new gaskets but have yet to test any of that to see if it will fix the issue. Have yet to test the spacers either to see if percolation was part of the issue.

Clean up around the O ring seat and possibly get some new mixture screw O rings. That's not your problem though. Might be just old, dirty seat or it got smoking hot and distorted. I'm still betting on heat soak.

I did pop some new o-rings on there so we'll see if that fixes it. I also bought some spacers to reduce heat soak so we'll see if those help too

the screws you're talking about, idle air mixture, SHOULD have little metal caps under the springs.

They do, looks to be made of brass maybe? There is a spring with a cap underneath it, and an o-ring underneath the cap.

correct. one less thing to worry about.

All:

Just fired the old girl up with everything mentioned above. Still gurgles. No difference. I still see fuel on top of the butterfly and I imagine it is still leaking from the mixture hole as well. I have a theory that if I put pressure on the butterfly and force it closed a slight but more than it will stop dribbling fuel on top of the butterfly because it seems like when I do this it stops but I could be losing my mind or it could be a coincidence lol.

You installed the spacers too?

This fuel you see on top of the butterfly, can you tell us where it's coming from? The pump jets, the aux vent or from some other location?

We really need pictures to help you.

When you open the butterfly, even slightly, you actuate the accelerator pump. That squirts fuel from the pump jets. There will be one on each throat of the carb.

What type if any fuel pressure regulator are you using. Pressure is paramount no more than 3.5lbs. Also very carefully check the carb top gasket and make sure none of the ports are blocked or partially blocked.

It appears to be coming from the progression/transition ports.

I'm using a Holley regulator with a seperate gauge. I have it set at 2.5 now confirmed by the gauge. I just put new gaskets on and it still does it. I have checked that the ports are not blocked. It did it with the old gasket and with the new

Theres only a couple of reasons to have fuel leaking out of the progression ports with the engine off.

1- idle jet air vent blocked and you're siphoning fuel from the fuel well.

2 - heated soaked and its boiling up and out.

3- flawed casting. (Seriously doubt it)

Check the vent really well and ensure its clear. Did you install the spacers?

That is what I meant earlier.
It sounds like you are pressurizing the bowl.

Any chance you are using a really powerful pump?
I have heard of fuel pumps cavitating and blowing bubbles into the fuel.

This was happening with some of the guys at the track that run E85 & megasquirts.
They couldnt figure out what was happening until they put in a clear fuel line.
That was with a high pressure FP and FI, but still a thought.

The float bowl vent (which is a huge slotted hole) and the idle jet vent are two different things.

Idle jet vent is kinda like the AC jet for the idle jet. Air sucked in there mixes with fuel from idle jet and gives you your idle mixture.

I haven't checked the float bowl vent just yet. That being said, the carb leaked from the mixture screw hole with the gasket and float completely off the carb so.

What keeps the fuel from dripping on its own on these carbs? I mean the mixture screw is at the bottom of the carb and the progression ports are fairly low too. Since gas is above these points what stops fuel from leaking just by way of gravity?

Before I bought the regulator my gauge was reading 4 psi so I don't think that would be the issue. I wish the fix was just too much fuel pressure

I did install the spacers. However the motor wasn't even remotely warm and it still did it. I let the car idle for maybe 60 seconds.

What is the best way to clean those idle jet air vents? I have blown through with carb cleaner and air and when I do I can see it spraying into the float bowl and if I remember correctly it comes out of the progression ports as well. Is anyone sticking safety pins or anything in there to really make sure it is clean and there isn't a hard piece of debris or something like that in there?

The idle circuit takes its fuel from the main fuel well. It then loops up higher than the float level and then comes back down to the progression ports and mixture screw. The idle air jet is at the top of the loop which breaks the siphon and stops the flow. A plugged idle air jet won't break the siphon and fuel will continue to flow until the float bowl is empty. Your idle mixture will also be super rich.

To clean it, remove the idle jet on the offending cylinder and blow from the vent (idle air jet) down. You'll easily see when it's clean. If there's crud, make sure to get it out so it doesn't plug up the idle circuit. You can stick something in there as long as it doesn't booger up the hole. Get that whole circuit super clean.