Fuel Line pack nut thread type?

[NealW]

I'm in the process of reassembling a 1911 touring that I'm restoring, and the Holley H1 carburetor has an elbow on it shown in the first picture. Corey Walker did a beautiful job restoring this carburetor! Anyway, I want to add an inline fuel shut off valve and consequently can't use the 90 degree shutoff valve that the vendors sell.

I do have an inline shutoff valve that came with the car (second picture) and it threads onto the Holley elbow. The fuel line pack nut sold by the vendors also threads on, so it the shutoff valve and Holley elbow have the same thread as the fuel line pack nut. What I need to find is a male union with the "pack nut" thread so that I can attach the fuel line pack nut to the union, the union to the inline valve, and then the inline valve to the Holley elbow.

Does anyone know what the thread type is on the pack nuts so that I can try to find a male union for it? It does not appear to be a pipe thread, and the last picture shows the Lang's pack nut attaching to a 90 degree elbow with piece that goes over the fuel line to make the seal. I suspect whatever union I find will need to use those as well. Any help/suggestions would be appreciated.

Thanks,

Neal

[Scott_Conger]

Neal

it is 1/2-18 thread

do NOT use anything which requires a compression ferrule...you will eventually break off your fuel line using such a thing as the mating part on the carb is not machined to be compatible with it. Use only the original felt or a neoprene gasket there and you will retain the originally designed flexibility at the union while also maintaining a leak-free joint.

[Steve Jelf]

What Scott said.

I would use the stock #2910 pack nut and #6154 elbow. A bit of neoprene fuel hose that fits inside the pack nut makes a good leak-proof gasket.

For a shutoff I use the sediment bulb valve. With an extension handle under the running board I can close and open the valve without crawling under the car. https://dauntlessgeezer.com/DG106.html

[Allan]

Does the tap screw onto the carburetor elbow? Does it screw on in the same way if you turn it around? If the answer is yes then you need a double male ended piece we call a nipple in Australia. Screw one end of the nipple into the tap, the other should take the standard T packnut, with its felt/neoprene seal.

Allan from down under.

[Steve Jelf]

Looking at the carb photo, it appears that the "elbow" is actually a standard brass nipple (a piece of straight pipe), not necessarily a Holley part. If this is like other Holley carbs (G and NH) the nipple is screwed into a standard ⅛" NPT hole and the #6154 elbow should fit. I'm guessing that the hole can be rotated to face the right side of the car to accommodate the elbow.

[Scott_Conger]

Steve

the elbow on the carb is indeed a Holley part, and terminates in the standard fuel fitting thread (1/2-18)

the standard fitment into the car is simply the FORD fuel line to that elbow. Job done.

any fuel shutoff will need to come before the standard 1/2-18 compression fitting on the carb elbow

[NealW]

Scott is correct. Here's a picture from McCalley's book showing the Holley H-1 with the provided elbow. My H-1 is the two screw cover type with the screw clamp for the hot air pipe.

[KWTownsend]

Neal,
It has been my experience that any valve used with a 1/4" fuel line yields insufficient fuel flow. I used to like 5/16" fuel lines. Now 5/16" fittings are hard to find. I would suggest you use what ever combination of fittings you can to make it work. What is the thread on the valve shown? I believe it is a valve for indoor residential gas lighting. I used one on my car, too with a variety of fittings, ending with 5/16" to 1/4" connector and then 1/4" pipe to the carburetor. Does the center-of-tank outlet use the same valve as the end-of-tank outlet?
-Keith

[NealW]

Keith,

The 15 runabout that I restored has a stock 1/4" line from Langs and I use the 90 degree shutoff valve at the carb. No fuel flow issues with it for me, but we also don't have hills here to deal with. Our local T club is called the "Flatland T's" for a reason...

[Steve Jelf]

Our local T club is called the "Flatland T's" for a reason...

Well, we do have some hills.
They're just shorter than the ones back east or out west.

[RajoRacer]

We'd call that more of a hump out here in the Pacific Northwest !

[TXGOAT2]

Pesky Mound Builders.....

[Art M]

Come to northeast Ohio, you will see real flat land. You can see the curvature of the earth.

Art Mirtes

[Quickm007]

What Scott said.


IMG_2708 copy 2.JPG
I would use the stock #2910 pack nut and #6154 elbow. A bit of neoprene fuel hose that fits inside the pack nut makes a good leak-proof gasket.

For a shutoff I use the sediment bulb valve. With an extension handle under the running board I can close and open the valve without crawling under the car. https://dauntlessgeezer.com/DG106.html

I already trying 2 times using the compression ferrule with nut and as said Scott, it failed. Use the neoprene instead work very well