Antique Auto Fuel Shutoff Troubles

Topics include, Machine Tools & Tooling, Precision Measuring, Materials and their Properties, Electrical discussions related to machine tools, setups, fixtures and jigs and other general discussion related to amateur machining.

Moderators: GlennW, Harold_V

Post Reply
hddennis
Posts: 13
Joined: Sun Jun 27, 2021 7:49 pm
Location: Byron, Georgia

Antique Auto Fuel Shutoff Troubles

Post by hddennis »

Forgive me if these are stupid questions but I'm not a machinist but need advice from one. My 1917 Maxwell's fuel shutoff started leaking recently and after removing it I took it to my local machine shop and no matter what I did I couldn't get him to understand that the brass shutoff had a metal to metal seal and all I wanted him to do was reshape the needle and make the seat match. I left in disgust and tried by hand to very gently rotate a drill bit in the body and hand sand the needle tip. I have managed to slow down the leak but not stop it. Next week I plan to try another machine shop in the hopes that they can help me save this part that took me 4 years to find. Is there a certain angle that I should tell them to put on this needle? The needle is 1/4 x 28 TPI but the tip is .200 . Also if a new needle needs to be made can it be made the same thread but slightly oversize in diameter to make up for wear from age?

Thank you for any help or advice you can give me,
Howard Dennis
Fuel Shutoff 1.JPG
User avatar
Harold_V
Posts: 20231
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: Antique Auto Fuel Shutoff Troubles

Post by Harold_V »

For starters, using a drill for any attempt at improving the valve seat isn't a good idea, especially in brass/bronze. It is notorious for self feeding and offers the real risk of destroying the seat, or, for that matter, the entire assembly.

If you can find a qualified machinist, there's no reason why the replacement can't be made with an oversized thread.

It is important that any work done on the seat results in perfect concentricity with the female thread, so when the needle is inserted it centers properly. For that reason, ANY hand work should be avoided.

The thread for the needle should NOT be made with a die, and any seat work should be done with the valve should be done with the body rigidly held in a mill setup, with the spindle dialed in with the existing thread. A boring head is most likely going to be required. Even with a mill, drills should be avoided for the reason stated above.

Restoration is possible so long as you have not damaged the part by hand working. Even then, depending on the qualifications of the chosen machinist, the part can be restored by bushing and re-machining. With luck, it will look stock when finished.

You make no mention of your location. That's not a good idea. You may live within walking distance of someone who would share their time with you in affecting a reliable repair, but how is one to know? There is no mandate that you provide your location, but I, personally, tend to shy away from trying to help anyone who prefers to remain anonymous. Your choice. If you choose to provide more information, no need to give your address. Narrowing it down to the state in which you live is quite helpful.

H
Wise people talk because they have something to say. Fools talk because they have to say something.
Russ Hanscom
Posts: 1955
Joined: Wed Mar 15, 2006 11:10 pm
Location: Farmington, NM

Re: Antique Auto Fuel Shutoff Troubles

Post by Russ Hanscom »

Looks sort of like the fuel valve one use to find on single cylinder engines, but those were smaller. One long shot would be to contact a small engine shop - they should at least understand the part and how it works.

The seat may have square edges or a short tapered section - you need to understand what is there so it can be properly fixed before damage is done.

Any info online or elsewhere about the part - should be something somewhere.
hddennis
Posts: 13
Joined: Sun Jun 27, 2021 7:49 pm
Location: Byron, Georgia

Re: Antique Auto Fuel Shutoff Troubles

Post by hddennis »

Thanks Guys, I live in Byron, Georgia as does my Maxwell. I've looked for years for this original Maxwell shutoff and have probably provided the most information that exists on it in the last 3/4 of a century.

Howard Dennis
Russ Hanscom
Posts: 1955
Joined: Wed Mar 15, 2006 11:10 pm
Location: Farmington, NM

Re: Antique Auto Fuel Shutoff Troubles

Post by Russ Hanscom »

Replicating the needle should not be too difficult, if you need to do so, however, the seat more is likely is the problem site and the hardest to address.

A new needle could be created with a some 1/4" brass rod and duplicating the taper and thread on the existing one, then bending the outer end.

The seat is a bigger challenge; it is probably not removable. If it is, you could have a duplicate made. If it is not removable, it can probably be dressed by making a reamer of the same taper as the needle and using the needle retaining nut as a guide bushing; and going at it very gently. You note the leak is small, so only an infinitesimal amount of metal needs to be removed. Alternatively, a tool the shape of the needle, without cutting function, and tapped gently could restore the seat or be used as a lap.

Gently is the key word, you do not want to make the problem worse.
STRR
Posts: 469
Joined: Thu May 24, 2007 9:01 pm
Location: Westminster, CO

Re: Antique Auto Fuel Shutoff Troubles

Post by STRR »

I agree with Russ. There is another option. A lapping mandrel could be made to fit inside the threaded body, at the angle of the needle. Gently used by hand, it would reshape the seat to match the existing or a new needle. Basically, the mandrel would look exactly like the existing needle without threads.
pete
Posts: 2518
Joined: Tue Feb 10, 2009 6:04 am

Re: Antique Auto Fuel Shutoff Troubles

Post by pete »

There not stupid questions at all. If you don't know it's not a crime. Building working miniature globe valves or almost any type of shut off is and has been a more than common practice in the live steam and locomotive hobby for well over 100 years now. Given the number on this forum who have done so I'm a bit surprised one of them hasn't checked this thread yet. But the general idea is to make what's loosely referred to as a custom one off D bit reamer. You'd chose a heat treatable tool steel and machine the end of that to the correct seat taper and the valves bore diameter, exactly half that rods diameter is machined away and it's then hardened, tempered, polished and stoned to restore the cutting edges sharpness.

You then have a simple single tooth negative copy reamer to re-machine the valve seat. Used at a slow enough speed because it's only high carbon steel and to avoid chatter, the valve seat can be re-cut to remove damage, wear or even used to build a new one from scratch. Depending on how deep you tried to go with that drill or how much past wear is on that fuel shut off it may or may not be able to be restored back to a proper fluid tight working condition. Probably a good knowledgeable live steam enthusiast is what you want over even a professional machine shop. The rarity and value of that shut off means you really want someone who is very familiar with this type of work. Again and depending on wear, the needles face may or may not be able to be re-cut to the same matching angle the reamer was cut to. This isn't something that should be even attempted on a drill press although someone skilled enough could probably make it work. A whole lot better would be a good rigid vertical mill with the valve bore indicated in to be exactly concentric to the milling machines spindle C/L.
hddennis
Posts: 13
Joined: Sun Jun 27, 2021 7:49 pm
Location: Byron, Georgia

Re: Antique Auto Fuel Shutoff Troubles

Post by hddennis »

100_10021 - Copy.JPG
Thanks Guys for taking the time to post your advice and suggestions. A fellow on an antique auto forum has offered to assist me in restoring this valve so I should be able to return this valve to my Maxwell and continue my restoration. Appreciate all the expertise here.

Howard Dennis
Post Reply