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PostPosted: May 30, 2014, 7:18 pm 
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I've run into a problem and I am looking for some advice on a more or less permanent solution.

I have a homemade fuel rail on my Spitfire engine. The rail is made from a piece of extruded aluminum tubing made for this purpose. The ends are threaded for fittings. The fitting at the input end is leaking where the rubber o-ring has deteriorated. This is a straight 9/16 thread with no particular provision for an o-ring to seat - it's just a flat aluminum face, like the back side of the fitting itself.

I can simply replace the o-ring, but I was wondering if anyone had a suggestion as to a more permanent fix. The input hose is removed from time to time to insert a fuel pressure gauge, so there is some wear on the o-ring. Maybe it needs to be replaced every time the fitting is loosened???

Any thoughts?

Thanks

Bill


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PostPosted: May 30, 2014, 7:43 pm 
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That sounds like a ORB style fitting. Look it up and hit a hydraulic supply store for what you need.
Strangely enough one of my high school students just asked me today about the same thing for a rotary spitfire he has been building.

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PostPosted: May 30, 2014, 8:01 pm 
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Teflon tape? Correctly named PTFE, poly tetra fluro ethylene tape. The pinky red stuff that is 2.5 to 3 times as thick as the regular white stuff. I know that it's meant only for pipe thread joints but, like the old lady in the Frank's Red Hot commercial says, "I put that sh*t on everything".

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PostPosted: May 30, 2014, 8:36 pm 
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Not sure Teflon tape or any other sealant is a good idea. If some little bit breakes off and clogs a fuel injector, there could be a bigger problem.

Bill


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PostPosted: May 30, 2014, 10:23 pm 
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I don't know on my current cars, but I thought my old '86 Mustang had a fuel pressure test port on the fuel rail. It looked just like a bicycle tire fitting. Maybe you can get or scavenge such a fitting and put it in somewhere. If you have a leak, and you are also testing pressure there are a couple of things telling you you need this.

Good luck! If your pressure is 30 instead of 45, that would be a huge amount of lean. Does it have a fuel pressure sensor?

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PostPosted: May 30, 2014, 11:07 pm 
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Teflon tape is fine, used it hundreds of times, works great.

Make sure you buy good quality stretchy soft stuff.


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PostPosted: May 31, 2014, 6:56 am 
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LockTite works well if left undistrubed after it sets up. Gasoline has absolutely no effect on it.

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PostPosted: May 31, 2014, 8:00 am 
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Or good old permatex [look for the 10 yr old tube hiding in the bottom of your tool box :lol: ] Dave W


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PostPosted: May 31, 2014, 8:02 am 
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horizenjob wrote:
I don't know on my current cars, but I thought my old '86 Mustang had a fuel pressure test port on the fuel rail. It looked just like a bicycle tire fitting. Maybe you can get or scavenge such a fitting and put it in somewhere. If you have a leak, and you are also testing pressure there are a couple of things telling you you need this.

Good luck! If your pressure is 30 instead of 45, that would be a huge amount of lean. Does it have a fuel pressure sensor?


I have a fitting that can be installed in the line to mount a fuel pressure gauge. I don't usually leave to there, but only when testing. That may be part of my problem, since breaking into the line also funds to loosen the fitting. I could just leave the fuel pressure gauge mounted in the line, I guess.


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PostPosted: May 31, 2014, 8:08 am 
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BBlue wrote:
LockTite works well if left undistrubed after it sets up. Gasoline has absolutely no effect on it.

Bill

I kind of like the locktite idea. Do you have a suggestion as to which formulation?

Bill B


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PostPosted: May 31, 2014, 8:12 am 
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Suggest you replace your O ring and install a schrader for fuel systems like this:
http://www.dieselorings.com/1994-1998-f ... -mnpt.html

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PostPosted: May 31, 2014, 8:27 am 
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I've got the replacement parts on order, but they won't be here until next week. Thanks for the suggestion

Bill


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PostPosted: May 31, 2014, 10:17 am 
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Bill, Stop by your local Home Depot or Lowes or even Menards if they are that far South and pick up a neoprene o-ring in the plumbing section about the right size. I think all of their o-rings are neoprene. You'll be on the road this afternoon. If you need to get by until the right parts get there, perhaps a leather faucet washer? This will let you work on the lean issue in the interim.

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PostPosted: May 31, 2014, 10:52 am 
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Use a copper washer (or soft aluminum) not an O-ring if you have no recess for the o-ring to be trapped.
Using an un-trapped o-ring may/will result in a fuel leak as the o-ring can be pushed out by fuel pressure.

I cannot recommend tape or chemical sealers.

If this is a standard AN thread maybe you can use these washers with a built in o-ring.
http://www.speedwaymotors.com/Goodridge-SS902-09-Stat-O-Seal-Sealing-Washers-6-AN,1000.html

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PostPosted: May 31, 2014, 1:38 pm 
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Well, I got the leak stopped. I was able to get a replacement o-ring at a local speed shop. That and some permatex thread locker seem to have the leak under control.

I agree that a compression washer is likely a better solution, but this seems to be working, at least for now.

Bill


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