Fuel shut-off valve

Tony Hillyard

Tony Hillyard

Senior Member
Good Morning Everyone,

My May 1928 Model A Roadster has a leaking fuel shut-off valve. I ordered the one type that is available but the thread seems slightly different.

The valve that I took out appears to have a slightly tapered thread whilst the new one has a parallel thread.

Has anyone else come up against this problem?

I suppose at a push I could tap out the tank outlet with a parallel tap but I wanted to ask the experts first!
 
The original threads were tapered pipe threads and are preferable for their improved sealing over straight threads. If it were me, I would try to get the original type valve, otherwise, use an appropriate fuel proof sealant.

Don't forget the in tank screen.
 
Sounds like you bought a poor quality shut off valve .send it back!!

Bratton's sell a decent one with the correct thread.
I'm sure some of the other suppliers do as well
 
I bought it from Brattons Johnny. I have contacted them and am waiting to hear. The packet says it was made by Snyder's, so I have no doubt whatsoever it is good quality.

I have search other suppliers site and it seems that this is the only one available. Odd, don't you think!

Thanks for your input Dollar Bill, it will be interesting to see what I have to do to get a leak free shut -off valve!!!
 
If you have a valve but it's leaky like I did, buy the repair kit. They are easy to install and once done, they work well. As I recall, instructions are included.
 
Thanks Synchro909.

I did not know you could get repair kits. I have only seen this type of fuel valve repaired by cutting two groves in the tapered valve and installing silicone "O" rings. I used to have a 1939 Fiat Topolino that had the leaky fuel valve repaired that way.

Any idea who might supply the repair kit?
 
Hi Tony,
I believe the tank outlet is parallel and not tapered like the valve. Others will soon correct me if I am wrong.
 
Is the valve leaking past the taper and through the line, or is it leaking to the outside at the handle?

My early 29 was leaking past the taper, so I polished it and lapped it with fine valve grinding compound and then toothpaste. It sealed up perfectly. I also bought the packing kit from Bratton's and put grease on the packing and taper when I assembled it. It hasn't leaked a drop in 20 years, and it's easy to turn.

Be sure to add the pencil filter while you have it out, if you haven't already done so.
 
That was the first thing I tried Tom. I pulled the valve from the car, took the fuel valve apart, lapped it in with very fine valve paste, then finished it off with Brasso metal polish. It still leaked.

So I ordered a new one. Then my problems really started.

It seems the fuel shut-off valve leak is an on-going niggle!
 
Thank you 3.6rs.

That is exactly my problem. I am wary of recutting the tank outlet thread.

I have a Pfaff industrial sewing machine. I needed a small replacement screw. I ordered one from a sewing machine specialist, when it arrived it was a terrible loose fit. It seems sewing machine manufacturers had their own threads to stop customers using other manufacturers parts.

So when it comes to my fuel tank outlet being recut to fit the new fuel outlet valve...... will the thread tap I will need to buy be the right one. BSP or NPT or some other mickey mouse type. A real minefield!
 
I would figure out what is up before cutting the threads in the tank.. the under tank thread is 1/4 pipe. And the late 31 valve outside the firewall is 3/8 pipe..

What about a brass adapter?? Just saying

Were overseas cars sometimes manufactured with different threads? Or was the bung replaced at one time?
 
Mine leaked but not where it threaded into the tank. I overhauled it in the car and it worked great and didn't have to worry about resealing back into the tank.

John
 
I doubled checked Chris, it is a tapered thread without a doubt.

Mitch, my Roadster is US made. One family owned it from new up in Minnesota. I even have the original drivers handbook and bill of sale from 1928.

I wondered about a brass adapter, then thought the more joints, the greater chance of a leak somewhere else!

I looked round for a repair kit and fuel proof grease is included. Anyone have an idea what is the base of fuel proof grease? It must be silicone or something.
?
 
Mitch//pa said:
I would figure out what is up before cutting the threads in the tank.. the under tank thread is 1/4 pipe. And the late 31 valve outside the firewall is 3/8 pipe..

What about a brass adapter?? Just saying

Were overseas cars sometimes manufactured with different threads? Or was the bung replaced at one time?
Click to expand...

Mitch is correct . I put these in from Snyders all the time and haven't had a problem yet. The new valve is the best solution as is for most driver cars you don't want to leak.
I have had trouble getting a couple started. But they eventually went.
The taper on your old one may be more at the bottom making starting easier. It wouldn't hurt slightly to use a 1/4 pipe tap to see if it starts.
Check first in the new valve. I think you will find it will mate.

I will pull one from stock and check as I have two tanks out right now
Larry
 
Thanks Larry,

Do you know if originally the thread was tapered or parallel 1/4" pipe thread. I presume that is NPT rather than BSP thread.

Here in darkest France a tap for NPT pipe thread would need to be ordered on US eBay,
 
tony,
I checked a snyder repro against an original and they are both 1/4 pipe and fit my tanks fine. Try a 1/4 pipe die if you have one on the valve side and see if it fits. Make sure you're not trying to put the compression seat end in the tank port. Just a thought.. it can happen! I've installed many of these without issue. I can't imagine you have one with an oddball thread.

Keep us posted. all the best!
Larry Shepard
 
Try EZ Turn to seal and to lube the valve. I have used it and the valve turns easy and does not leak. I have also used it on oil lines with no leaks. I read it is used by Rolls as a back up to the o rings to seal the fuel lines on their jet engines. Got it from Sky Geek.
 
Synchro909 said:
Larry, Snyders have the repair kit but look out - it will cost you a whole $1.60.:D
http://www.snydersantiqueauto.com/gas-valve-repair-kit
Click to expand...


I know.. I have used it before. Thank you for bringing it up thow. Folks may want to try it in some cases.

Using/Restoring originals really boils down to getting the two mating surfaces tight and mating well. I've tried different processes before to lap them together, lighty polish for a good fit... but in the end few sealed leak free through the line. Packing wise is not the problem as much as fuel leaking past.

I tore apart many for Dan Bixby one time.. they can be a pain.
For service work for "driver cars" the new one is less money and hassle when you consider your time and effort.. in hopes of making it perfect and if it's not you already have gas in the tank. I really like putting a vacuum pump on things like this and see if it will hold. If it won't hold, it will leak. Just like carb needle/seats.

Larry
 
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