Holley NH carburetor leaks when cranking engine

[bmklawt]

searched the forums and can't find an answer to this. I have a 1927 Touring, new to me, had it running for a few minutes, but am afraid to run it with the leaky carburetor, it has supposedly been setting for the last 10 plus years.
When I crank the engine over for 5 seconds the carburetor starts to drip gas, I have not been able yet to see exactly where it is coming from, when I go to look the whole bowl is wet.
It does this with the choke on, off or anywhere in between, much worse with the choke on, If I open the needle valve a 1/4 turn I'll get a few drips on the floor, 1-1/2 turns it will drip for 20 seconds after I crank the engine for 5 seconds. I have rebuilt the carburetor, set the float to 1/4" from machined flange, drilled out the passage plugs, cleaned the passages and plugged them with 8-32 set screws, I did not put any kind of sealant on the set screws, I did the passage plugs after I had it running once, it won start now, I had the intake and exhaust off and replaced the gaskets with the original type, engine has a distributor on it with a vacuum line going to the intake manifold. I'm at a lose as why it leaks.

Your help is greatly appreciated,
Bruce

[mtntee20]

Hello Bruce,

Under normal conditions, you may get some leakage from choking while cranking. My first thoughts are the float level is too high causing the leakage. You may have a float that is sticking keeping the needle valve open. Another possibility is the needle valve may be fouled, sticking, or worn/damaged so it doesn't seat properly. I am not an expert on carbs. It would help others to specify what carb you have. It looks like a Holly NH but I'm not 100% sure.

Good Luck,
Terry

[bobt]

Replace the needle and seat. Try to get a viton tipped needle.

[speedytinc]

If the carb leaks when the gas is on, static, the needle is not sealing. Otherwise its fine. When the T is cranked, fuel flows up the manifold. When you stop cranking, the fuel flows back to the carb. That becomes excess & drips off. All normal. Pix shows full on choke. Is the choke lever return spring working? When you release the choke pull, it should return to a full open position.(spring back)

[JohnM]

You may want to move the vacuum line and plug wires away from the exhaust manifold before they melt and leave you stranded.

[Bill Robinson]

Good eye John K!

[JohnM]

A spark from a melted plug wire near a leaky carburetor is a BAD recipe!

[George Mills]

Probably a stuck float?

Yes worth checking float valve needle for stick before close, but old time trick it have someone to rattle the carb body with the back of a wrench while you use starter. Stuck hinge on float will usually 'pop' and behave. Doesn't fix it, but tells you what it is.

(I rather like your carb mounting nuts, especially on the inside part of the flange! )

[paddy1998]

(I rather like your carb mounting nuts, especially on the inside part of the flange! )

Yes. That is a helluva setup.

[Norman Kling]

If it doesn't leak when the gas valve is open, but only when cranked, your problem is not the float or float valve. As pointed out above, the choke appears to be closed in the picture. First take the wire off the choke lever and a spring should open the choke. If it doesn't open, the spring needs to be replaced. Otherwise the wire is too short. From the picture, it appears that the attachment to the choke rod is too high on the rod. It should be just above the cotter pin, so I am assuming the spring is broken. It can be ordered from the parts suppliers and fits right where the choke shaft goes through the carburetor. You can verify by manually opening the choke and then crank without choking to see if it still leaks.
Norm

[RajoRacer]

The the choke wire is attached onto the incorrect hole on the arm - it should be in the "front" hole - secondly, the choke sleeve should be below the cotter pin - not above it but if the sleeve was lower, the cotter pin could pull the sleeve up but it can't because the choke wire is withholding it back from working as designed - it's all wonky !

[speedytinc]

The the choke wire is attached onto the incorrect hole on the arm - it should be in the "front" hole - secondly, the choke sleeve should be below the cotter pin - not above it but if the sleeve was lower, the cotter pin could pull the sleeve up but it can't because the choke wire is withholding it back from working as designed - it's all wonky !

I dont know what you are seeing. What I see is:
The choke is full on. The upper lever hole is forward. (missing the front of radiator choke wire). The lower lever hole is up. The cotter pin is resting on the mixture adjusting sleeve, where it needs to be to pull up the choke wire sleeve. Release the choke knob & the return spring pulls the choke wire sleeve down into its neutral resting position. If the owner manually slides the choke sleeve down to its normal resting position, it would all look correct.
Either the choke return spring has failed or there is a bind in the linkage keeping the choke open.
With this condition of full choke, when he cranks the car, tons of fuel is being sucked up the manifold. When he stops, all that fuel drains from the bowl breather hole, air mix hole & past the choke butterfly in that order & combination.
If left this way, without a choke return spring, bouncing while driving can suck the butterfly closed, intermittently. Acts like a defective ignition switch. That makes for some real head scratching. Seen it.

[Scott_Conger]

It is very hard to see in the photo, but Speedy has correctly diagnosed the permanently closed choke. The photo is at just the right angle to believe the hand-choke lever is broken off, but it's there. In any event, the only way a choke lever on an NH is parallel to the ground is if the choke is approximately 1/2 closed when at rest

[bmklawt]

The choke lever was being held open on purpose when I took that photo, I was trying to figure out some kind of stop as I can pull the choke to hard and bind it, it was not stuck open when when I was trying to start it, the choke spring does return the choke to open.
The needle valve and seat were new but today I replaced it with another one I got from Scott Conger called a "Full Flow Float Valve Kit" and replaced the bowl gasket, it started right up and the carburetor no longer leaks.
Good call on the plug wires, thank you.

[RajoRacer]

I appreciate being corrected by experts. I'll get my eyes re-examined !

[Scott_Conger]

Nothing succeeds like success

now, go have fun