jisnardi

I have a 66 Roadster, with a Holley 3367 carb. Last week while driving it just stalled out sounded like I just turned the key off. I pulled the air cleaner and there was fuel flooding everywhere. I soaked up the fuel, waited till it was cool, and turned it over. The fuel was gushing from the front vent tube.

I pulled the carb and did a carb rebuild kit. At first it did it flooded again, so I pulled the carb back off and re adjusted the floats. It started and ran perfect.
Today, I pulled the air cleaner off and started her up. She idled perfect. I took it around the block, and still ran perfect. So I decided to take a further ride. I drove about 2 miles, and it stalled out again, doing the same, gushing gas from the front vent tube.
Can anyone suggest what I am doing wrong, or what is causing this issue? Could it possibly be a bad float???????? I also found a couple droplets of water in the gas when I drained the carb after pulling it off
Any help would be GREATLY APPRECIATED !!!!!!!!!!!!!!!!!!!!!!!

ghostrider20

Is/was there fluid inside the float bowl? If so it will not float up and shut the needle valve off. Secondly, did you change out the needle valve? Something may be binding and not allowing the float to raise and shut the needle valve. Make sure the plastic housing that slides on over the needle valve is snug and not interfering.

Are you running a stock fuel pump?

jisnardi

There was gas in the float bowl. I did change the needle valve for the float . The plastic housing was snug. And I am running a stock fuel pump, not electric. I am lost

tbarb

Yes, it could very well be a heavy float and also rust in the fuel tank causing the needle not to seat. The float is where I would go first if the fuel looks clean and make sure it's not binding on anything inside the bowl.

John S 1961

Too much fuel pressure. Only way fuel comes out of the vent is if the fuel bowl is full and still pumping not stopping. Even if you replaced the valve doesnt mean it shuts off.

ghostrider20

Fuel in the float? Then replace the float.

DansYellow66

Checking the fuel pump pressure, the float for fuel inside and for junk in the needle/seat as mentioned above are all good ideas. I would also make sure the float moves freely in the bowl and doesn’t hang up on anything. Also suggest you change the oil as it’s probably getting pretty contaminated by the flooding.

Tampa Jerry

All great advise. If that fails, I use an old school guy in Tampa that specializes in rebuilding Holley carbs. I have been to his shop and he has the parts, test engine and flow equipment. The FEDX ground turn around time in Florida is usually one day. PM me if interested. Jerry

jisnardi

PM sent, thank you!!!!!!!

jisnardi

Ok, so after rebuilding the carb, and breaking down on a test ride again I finally found the root of my problem.

After setting the float for the 6th time, fuel kept flowing out the front vent tube. I immediately pulled the carb, and pulled the front bowl. I noticed the float assembly, where the arch closes the needle to cut off fuel, was not hitting the needle, hence never shutting off the fuel flow. From my limited experience I felt there must have been a spacer between the c-clip and the float assembly on the pin that the float assembly rides on. I pulled the clip and removed the float assembly to find the pin itself loose. The pin pulled out of the bowl with just my fingers. I cleaned everything and reset the pin, and taped it down lightly with a small hammer. It seated firmly. I reassembled the float assembly and adjusted the float. Reassembled the carb, put it back on and fired her up.
Worked, no fuel out the vent. check the float through the viewing hole, perfect height.
All back together, no leaks and running good, maybe a little rich. My next quest is to learn how to adjust the carb.
PICTURE BELOW IS AFTER I FOUND THE ISSUE AND REASSEMBLED. Just to reference what I was attempting to explain above

Tampa Jerry

Joe: I am glad you were able to figure it out and fix it. For tuning, once the floats are adjusted, use a vacuum gauge and adjust the A/F settings to the highest vacuum setting. Start with 1 1/2 turns out after carefully bottoming out the screws. Set with a warmed engine. Others will post with their methods. Jerry

ghostrider20

Holley’s like to start at 1.5 turns out on the idle air mixture screws. Don’t run them down tight, you will damage the needle. Remove them and inspect the needle to ensure it’s not bent or deformed. Then gently turn them in until they bottom out. Hen turn out 1.5 turns.

Vet65te

Joe - Nice detective work. It's amazing how something unexpected like a loose float pivot pin can cause problems like that. After my 66 L79 sat in a body shop for 8 months and repeat starts to move it a short distance and then shutting it down, when I got the car back, the carb had been only running on choke and it was a bit gummed up. Installed new plugs, cleaned the carb out, double checked settings (which as expected, hadn't changed) and put it back together using those reusable Blue Holley Gaskets. I've used them numerous times and never had a problem. About 50 or so miles later, coming home from the Saturday Morning Donut Shop get-together in town, the car all of a sudden lost some rpm and ran a bit ragged. Did the usual to stab my foot on the gas pedal to see if that might help (never does but hey, old habits are hard to break, right). It ran okay but oddly, the idle rpm was no longer 750 but more like 600 and it had a slight miss on the way home. Got it home, started checking ignition and carb and found no smoking gun. Pulled the carb apart and found something I hadn't expected. A teeny chuck of the somewhat foam rubber material that Holley uses for their reusable float bowl and metering plate gaskets had dislodged and stuck in one of the idle air bleeds. You'll have to look closely to the lowest air bleed hole to the left of the power valve and you'll see that little bit of gasket material had plugged it up. Pulled it out, gave it a shot of cleaner, reassembled everything and all is right with the world again...until the next time :-O.


Mike T - Prescott AZ

tbarb

Mike, you probably meant to say idle jet not idle air bleed.

That idle jet hole controls the amount of fuel allowed into the idle well, the fuel gets drawn through that jet then up top and mixed with air from the idle air bleed then down to the curb idle port and transfer slot. The air bleed at the top will prevent any suction being formed by engine manifold vacuum. The idle air bleed hole in the main body top will line up with the idle down well, (long vertical slot on the left side of your picture).

Many people go the the main jet to lean or richen the carburetor and that's good except when the engine is running on the idle circuit which is usually up to and beyond 2000 rpm. Tuning in this range involves the idle feed restriction and idle air bleed. In most cases it's close enough unless you have experience in this type of tuning.

Vet65te

Tbarb - Yeah I have a tendency to call those small orifices idle air bleeds, forgetting the true name. When that little bit of 'schmutz' got stuck in there, the cars reaction was unlike anything I'd ever experienced with a carb acting up. I could rev it up and then listen to it drop down, thinking it was about to die but it didn't, it just ran at a lower rpm. On the 12 mile run back home, the miss I spoke of was really kinda intermittent. Just like Joe finding that pin having gotten loose, it's not a common problem but maybe not too uncommon either.
Mike T - Prescott AZ

66427-450

Just a comment, excellent thread. The sharing of operating experience like this is one of the huge benefits of this forum, in this example, two potentially generic carb symptoms/issues that others here could be challenged with at some point……… this forum is a real asset; assisting each other in the maintenance of these cars we love, sharing the knowledge/information we’ve acquired through the years, as well as just expressing our mutual admiration of them (the camaraderie thing). Again, good to see members invest the time to document experiences like this, that may benefit others.

LouieM

Good detective work. Never ran across that problem.