11-A Distributor Thread Size

[Ramjet47]

I have a stripped thread on a distributor I am overhauling. What is the thread size of the vacuum connection?

[Mart]

3/8 -24 UNF. 99% sure can anyone confirm?

[rockfla]

NO expert BUT being a brass fitting/tube wouldn't it be a "NPT" or a National Pipe Thread because "Machine" threads do not "seal" so you couldn't seal the "vacuum" with a machine thread!!! MY "guess" would be a 1/8th NPT or 1/8 National Tapered Pipe Thread!!! AS I said....MY GUESS

[Mart]

Rock, no, mate, I just went and checked, it is the fitting for a 3/16 tube, which is 3/8-24 UNF.

A 3/8-24 tap screws in nicely but a 1/8 NPT barely starts and goes tight straight away.

It was late when I posted last night, but was able to do a physical check today.

The nut has a tapered end which bites into the pipe.

Mart.

[Mart]

If you've stripped it, you could go 1/8 NPT and use an adaptor to get back to 3/16 tube.

[rockfla]

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Damn bad day IF you don't "Learn something" everyday!!!! Good day, today!!! Thanks Mart

[deuce lover]

Here is the fitting it takes I think.3/8 24 as Mart said

[JM 35 Sedan]

Originally Posted by rockfla

NO expert BUT being a brass fitting/tube wouldn't it be a "NPT" or a National Pipe Thread because "Machine" threads do not "seal" so you couldn't seal the "vacuum" with a machine thread!!! MY "guess" would be a 1/8th NPT or 1/8 National Tapered Pipe Thread!!! AS I said....MY GUESS

The sealing required at this fitting would not be accomplished at/or by the 3/8-24 threads.

[JSeery]

Originally Posted by Mart

If you've stripped it, you could go 1/8 NPT and use an adaptor to get back to 3/16 tube.

Mart, wouldn't any adapter require a provision to seal the original 3/16 fitting. I think it is going to require some measure to repair the existing threads or switching to some other method to seal the 3/16 tube with the adapter. Unless there is an adapter that provides the seat required for the original fitting.

[rotorwrench]

That was Ford's original compression fitting that was used clear up into the 60s at least.

[tubman]

I've always known them as "Ford Nuts".

[JSeery]

Ya, I would really think hard about any attempt to tap it out to a different size, could really open up a can of worms.

[supereal]

Ford used a lot of unusual thread sizes and pitches. At our shop we aways save any "left over" nuts and bolts. We have several coffee cans of them, and have been glad we did.

[Ramjet47]

Thank you to all who replied. I have now re cut the thread back to 3/8”x24 UNF, not perfect but with thread sealant it will be OK. Best regards Roger.