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Fuel Shutoff Advice Sought


hddennis
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882772841_FuelShutoff2.jpg.c9206f395a6a8def1d9d3c60b493030f.jpgForgive 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 Dennis226338376_FuelShutoff1.JPG.68dce1f3443937f5ce073f4f99611c7a.JPG

Edited by hddennis (see edit history)
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Any competent machinist should be able to fix this problem. The worst part would be the seat. I can envision several ways I might approach the problem and none of them are especially difficult. As for your question about angles... The angle is not critical, the needle just needs to meet the seat at the edge and "seat". I might even be tempted to look into a ball end on the needle and a cup seat. More work, but easier for todays machinists to understand. Look for a machine shop that is smaller and older. You may find a treasure of knowledge there!!

Edited by 37_Roadmaster_C
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37 minutes ago, Larry Schramm said:

I would just put a ball valve in line where the inlet line goes into the sediment bowl.  This is what I use on my vehicles at the carb.

 

https://www.harborfreight.com/14-in-full-port-ball-valve-63553.html

Thanks Larry,

But I spent 4 years hunting down this oddball looking shutoff that Maxwell used and am trying my darndest to keep it original as built.

 

Howard Dennis

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Morning Howard.

Lots of good and bad news here.

I would recommend a seat/needle angle of 45 deg. Much less than that and you will start to get into a binding problem. Making a new needle is likely no problem. Assuming there is enough "meat" in the body re-cutting the seat is another matter. A 45 deg cutter will be required. The bad news is MSC sells a 45 deg end mill but at $103. The good news is a 45 deg "D" cutter could be made from any tool steel and would be fine for a one time use in brass. The bad news is a machine shop will charge way more than $103 to make the cutter. 

The bad news is fixturing the body to be perfectly aligned with the 1/4-28 needle bore may  be a bitch. The good news is maybe not. The good news is a D cutter could likely be fashioned to ride in the needle bore for alignment eliminating the fixturing.

The good news is your fuel shut off  likely can be repaired. The bad news is most any machine shop is unlikely to be interested.

Email me a pix of the needle removed from the body..... bhigdog1@ptd.net.........Bob

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All the above actions & recommendations are a bit heavy handed to make this antique valve seal. 

 

All that was needed was some fine grinding compound (or toothpaste) to hone the needle to the seat. 

 

Just my opinion as a retired industrial valve specialist.....

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17 minutes ago, Mark Shaw said:

All the above actions & recommendations are a bit heavy handed to make this antique valve seal. 

 

All that was needed was some fine grinding compound (or toothpaste) to hone the needle to the seat. 

 

Just my opinion as a retired industrial valve specialist.....

 

Understand your concept, But how do you hone the needle when it is threaded into the housing??

Howard Dennis

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11 hours ago, hddennis said:

 

Understand your concept, But how do you hone the needle when it is threaded into the housing??

Howard Dennis

 

This is a valid question. I will not attempt to answer as I do not have the parts in hand. Another way to repair that is easy and should work well is as follows: disassemble the needle and seat assemblies. smooth the needle and clean all parts well. Coat the needle end and seat with soft solder. Blow any excess solder out of the seat assembly. Reassemble and shut off snugly to reform the needle/seat seal in the soft lead solder. This can work well on gravity feed systems and is easy to redo if needed in the future.

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7 minutes ago, 37_Roadmaster_C said:

 

This is a valid question. I will not attempt to answer as I do not have the parts in hand. Another way to repair that is easy and should work well is as follows: disassemble the needle and seat assemblies. smooth the needle and clean all parts well. Coat the needle end and seat with soft solder. Blow any excess solder out of the seat assembly. Reassemble and shut off snugly to reform the needle/seat seal in the soft lead solder. This can work well on gravity feed systems and is easy to redo if needed in the future.

 

I like your idea IF the seat was removable but it isn't.

 

Howard Dennis

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47 minutes ago, hddennis said:

 

I like your idea IF the seat was removable but it isn't.

 

Howard Dennis

 

The seat does not need to be removable. As the whole assembly is brass, just flux it up and heat gently with a torch until the solder melts when touched to the seat. Shake or blow clear and let cool.

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22 hours ago, hddennis said:

Understand your concept, But how do you hone the needle when it is threaded into the housing??

Howard Dennis

You don't need to rotate the needle 360 degrees. 

 

A back and forth rotation should work as long as you have not yet machined too much material from the mating parts.  

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8 hours ago, Bhigdog said:

Several ways to skin this cat.

Purpose made seat re-finishing cutter goes out this AM to Mr. Dennis. Hopefully a cleaned up seat will solve the problem with minimal muss, fuss, cost...............Bob

20210829_144649.jpg

 

Bob,

You are a very generous person and an exceptional asset to our hobby community!!  Cheers to you!!!

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  • 2 weeks later...

After I sent the seat cutter to Howard he reported no luck with it and asked if he could send the unit to me for repair.

I set it up in my Bridgeport but I also could not re-cut the seat. Further inspection showed the seat was so wallowed out and over size from past abuse that there was no saving it. A phone call to Howard gave me the go ahead to try to salvage it since there was nothing to lose.

Long story short: I bored the old seat completely out, threaded the bore for a 1/4-20 brass plug soldered in place, and then drilled/cut a new tapered seat for the needle valve. I sooted the needle taper and checked for good contact with the new seat.

The next problem was the needle shaft had no packing and would leak like a sieve. I cut a 60 deg taper in the body and made a matching packing from teflon. When the gland nut is tightened it wedges the packing tight effecting a good seal.

I pressure tested the unit to about 50 pounds with no bubbles. Since it only has to withstand  pressure from gravity feed I think it's good to go.

It goes back to Howard this AM.

Pics show a bit of the process, the purpose made tooling and the small teflon gland packing.................Bob

 

 

 

 

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Edited by Bhigdog (see edit history)
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