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Purchased a new Edelbrock mechanical fuel pump and I had to go to a 90 degree hose to NPT inlet fitting. So I use a liberal amount of ARP fitting sealant that I had left over from when I did my cylinder heads on the NPT threads. I tightened the fitting and its snug. I could maybe go another 1/4 turn, but then the fitting would not be lined up with the fuel hardline. I let the sealant cure over night although I'm not sure it actually cures. This is the type of stuff that stays soft.

Fired the car up. Seemed OK. Took it for a 10 minute ride and it leaked. I could see where the fuel had blown out all the sealant on about half the fitting and was bubbling out.,

SO much for the wriitng on the sealant tube that says can handle 10000psi of pressure! :rolleyes:

Thoughts as to where I went wrong?
 

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Pipe thread really should not need much sealant. The taper in the threads is what really seals it. Where did you get the 90 deg fitting ? One of my customers was complaining the other day that some fittings he got at the local parts store were made wrong and simply would not seal. He ordered some from McMaster Carr and the problem was solved.

If turning it further would seal it up then what might work better is to put a straight fitting in the pump and then use a 90 degree end on the fuel line.
 

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Discussion Starter #5 (Edited)
Pipe thread really should not need much sealant. The taper in the threads is what really seals it. Where did you get the 90 deg fitting ? One of my customers was complaining the other day that some fittings he got at the local parts store were made wrong and simply would not seal. He ordered some from McMaster Carr and the problem was solved.

If turning it further would seal it up then what might work better is to put a straight fitting in the pump and then use a 90 degree end on the fuel line.
I'm using one of those Spectre chrome fittings.

I think your correct about it not being tight enough. The problem with a solid 90 degree fitting is its unlikely the point at which its tight is going to exactly line up the inlet where you need it to. In my case, it really needs to be about 90 degrees tighter based on my "feel".

So I was faced with keeping it a little loose or attempting to tighten it another 270 degrees and risk cracking the fuel pump. The paste probably can't take up the extra space between the threads.

I found this. It might be an option. If I'm reading the description correctly, it says it swivels. SO I'm thinking it allows you to tighten it as tight as i needs to be and keep the inlet facing the direction IT needs to be.


Plus this...



Your idea about another 90 degree in the fuel line would work, but I'd have to find a 3/8" hose "nipple to nipple" 90 degree adapter.
 

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Are you using braided line ? If that is the case you need a straight fitting on the pump and a 90 degree hose end. End of problem. These two parts should do the trick if you are using -6 hose :

 

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>> Spectre chrome fittings.
And there you have it. those fittings are garage.
 
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And there you have it. those fittings are garage.
Purchased a new Edelbrock mechanical fuel pump and I had to go to a 90 degree hose to NPT inlet fitting. So I use a liberal amount of ARP fitting sealant that I had left over from when I did my cylinder heads on the NPT threads. I tightened the fitting and its snug. I could maybe go another 1/4 turn, but then the fitting would not be lined up with the fuel hardline. I let the sealant cure over night although I'm not sure it actually cures. This is the type of stuff that stays soft.

Fired the car up. Seemed OK. Took it for a 10 minute ride and it leaked. I could see where the fuel had blown out all the sealant on about half the fitting and was bubbling out.,

SO much for the wriitng on the sealant tube that says can handle 10000psi of pressure! :rolleyes:

Thoughts as to where I went wrong?
Just my $0.02
BillK sez: "...One of my customers was complaining the other day that some fittings he got at the local parts store were made wrong and simply would not seal. He ordered some from McMaster Carr and the problem was solved. "

Bingo! Yes it is possible that mass-produced machined parts can be defective.

Example: Faucet on my old laundry tub. Hose threaded swivel arm. Bought the adapter stuff to install one of those grocery store rubber gizmos that you can get a spray or a stream from. I got one on the kitchen faucet. Works good. When tried on the laundry faucet, wouldn't seal. Local water pressure is 53psi. Tried different washers and cranking it down a little with pliers. No go. I have no doubt that the flat face where the metal meets the rubber is not perpendicular to the axis of the threaded part. Manufacturing defect 70+ years ago.

As has been mentioned, tapered stuff seals on the taper. Yes, you use "pipe dope"; but for ease of disassembly. I have removed brass hose bibs from my 72 year old house with no difficulty at all. Without the dope used back in 1949, they would have been mighty tight. Something you can squeeze out of a tube resisting 10,000 psi pressure? Like somebody's Grandma supposedly said: "It don't make sense; so I don't believe it."
 

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Chrome stuff seems to leak moreso, but cheap chrome is almost a guaranteed leak.
 

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Just my $0.02
BillK sez: "..

As has been mentioned, tapered stuff seals on the taper. Yes, you use "pipe dope"; but for ease of disassembly. I have removed brass hose bibs from my 72 year old house with no difficulty at all. Without the dope used back in 1949, they would have been mighty tight. Something you can squeeze out of a tube resisting 10,000 psi pressure? Like somebody's Grandma supposedly said: "It don't make sense; so I don't believe it."
I agree 100% with doing things so you can get it apart later, but I would rather see antiseize on flare, JIC and SAE fitting threads. . Some thread sealers set rock hard and make fittings almost impossible to get apart. Antiseize is almost always a good idea on anything but pipe threads, but especially if you are joining dissimilar metals.
 

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Ryan
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Replace it with some quality fittings. I personally prefer Earls and Aeropquip but have had luck with most other brands including Summit.
 

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This is what we use on the big trucks and what I use on ALL my piping projects that call for thread sealer.

 

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Agree that you need better fittings then Spectre. That should, seal with a minimum of dope or PTFE, or a little of both without cranking on it.
 
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