The Ford Barn

JohninKuranda · 06-13-2025, 09:23 PM

I am just after clarification as to the thread size on the carb-mounted fuel shut-off valve (the thread marked in purple on the attachment). I am thinking that it is 1/2" - but wondering if it is UNF or NPT? Or is it another size?

Many thanks
John

redmodelt · 06-16-2025, 10:03 AM

1/2" (US) national fine straight thread.

Daisyarney · 07-01-2025, 09:00 PM

It’s most likely 1/2" NPT, since most carb-mounted fuel shut-off valves use tapered threads for sealing. However, to be sure, you could measure the thread diameter and pitch with a gauge or check the carb model’s spec sheet. Did you already check if it has a slight taper (NPT) or straight thread (UNF)?

redmodelt · 07-03-2025, 10:48 AM

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Quote:

Originally Posted by Daisyarney

It’s most likely 1/2" NPT, since most carb-mounted fuel shut-off valves use tapered threads for sealing. However, to be sure, you could measure the thread diameter and pitch with a gauge or check the carb model’s spec sheet. Did you already check if it has a slight taper (NPT) or straight thread (UNF)?

No it is a straight thread and uses packing to seal or in some cases a brass ferrule. The other end that fits into the carb is pipe thread.

06-16-2025, 10:03 AM	#2
redmodelt Senior Member Join Date: May 2010 Location: Portland OR Posts: 6,408	Re: Fuel Shut-off valve 1/2" (US) national fine straight thread. __________________ I know the voices aren't real but damn they have some good ideas!

07-01-2025, 09:00 PM	#3
Daisyarney Junior Member Join Date: Jun 2025 Posts: 1	Re: Fuel Shut-off valve It’s most likely 1/2" NPT, since most carb-mounted fuel shut-off valves use tapered threads for sealing. However, to be sure, you could measure the thread diameter and pitch with a gauge or check the carb model’s spec sheet. Did you already check if it has a slight taper (NPT) or straight thread (UNF)? __________________ unblocked doodle jump Last edited by Daisyarney; 07-02-2025 at 09:14 PM.