Hi
I'm currently trying to mount a fuel pressure gauge on my fuel line to the carb. The fuel line was there when i bought the car and it looks like attached picture with a small hole with allen plug.
I bought a summit racing fuel pressure gauge with 1/8 NPT threads.

But now when I removed the allen key plug the fuel pressure gauge wont even go in half the threads before it stops. I dont want to use more force because I'm afraid i trash the threads.
The allen plug goes all the way in though. Could it be that both the Allen plug AND the threads in the fuel line are tapered threads but the gauge itself is straight ?
I tried with Mr Gasket gauge but with same result.
Is this normal ?`
I was thinking of using threading tools to repair threads, but this might ruin the fuel line if they are tapered in the gauge threads.

Or is it just the way the gauge is mounted, like 1 full circle threads and keep tight and sealed with thread sealer ?

 

Go to Lowes. Get 1/8th pipe plug and female fitting. Check gauge with fitting and try allen plug in fitting too. Check fuel line with plug. Probably fine. They are all tapered threads. Some cut a bit deeper makes them wider.

 

Hopefully you find resolution to your problem.

Professionally speaking...the line you bought would NOT be the line I would buy and put on your car....and if you handed it to me to put it on..I would NOT.

Not that you asked...I will say this so it might give you something to ponder.

When the fuel line from the fuel pump to the carburetor is being installed. I do EVERYTHING I can to make sure that there is not ONE hose clamp....due to this line is under pressure...as minimal as it may be...it is still under pressure when the engine is running.

All of the fittings/connections are either the flare fittings like what is on this fuel line that you plan on installing where it attaches to the carb....or they are JIC connections....or even a pipe thread that allows you to install a fitting for JIC or inverted flare.

But the end down buy your fuel gauge port is made for a hose and clamp.

The reason I say this is that even thought they sell this stuff and people buy it...and have years of good service out of it....IN TIME...the rubber hose can get hard and crack or fail and/or the hose clamp loosens and WHAM...you can have a major fuel issue or fire..

NOW..if you are person who is under the hood all the time checking things...then I am sure you would catch a problem before it became a problem.

For me doing this for people..I CANNOT do it that way because I know they would not check...and one day..a problem that I would have to deal with.

DUB

 

Thanks for your response DUB.
Maybe I should have been more clear in my first post but the exact fuel line on the picture is not the exact one fitted on my car. I have a similar design but ofcourse with AN-fittings and no hose clamps. It has been mounted on my cars for ages from previous owner.
I appriciate your concern but my questions was not about that fitting at all, my big issue is with the fuel pressure gauge port on the example picture above. (small allen-plug on the fuel line)
As I wrote I thought that it was standard on both the fuel lines and fuel pressure gauges that the threads are 1/8 NPT.
The gauge i now is 1/8 NPT as it says on the package and I have two different gauges.
Unfortunately the gauge only turn 1 round of threads and then it feels as it's stuck. So as i wrote above, should it be like this or could i have different threads on the fuel line gauge port ?

 

Post a picture and it would be easier to see what you have.

 

Yes, here is the real thing 😊
The Allen plug in the middle fits the threads in the port all the way down. But both gauges get stuck after just 1 1/2 turn of threads.

 

Teflon paste on the gauge threads, screw that sucker in until it gets snug, then tighten up just enough to orientate the gauge. It'll be fine....


Often times, NPT plugs screw in much deeper then actual fittings, as they have much less taper.

If the gauge screws in a good 2-3 turns by hand, and then snug it up from there, its good. It won't screw all the way down.

 

Lay plug next to pressure gauge and take a pic of both threads together and post it.

 

I AM GLAD that you did not buy nor use the one that you posted a photo of. In the future. Post photos of the stuff you actually have so it can save some of us time typing out stuff that is being given to try to help out.

Having a photo of the actual plug that you took out would be GREAT.

From the little bit of it I can see on your air cleaner lid. I am wondering if it is a pipe plug at all or a regular set screw. I do not see a taper in it.

DUB

 

Here is the plug that works and the gauge that don't
Now taken the picture and being able to zoom in I see the threads don't actually align... 😊😁
That would then indicate that the plug and threads on the fuel line is NOT 1/8 NPT !!! 😔

 

I wish you did not have that black part in the background..

But when I did enlarge it. I swear it looks like the plug that came with your fuel line does not have pipe threads.

I do not think the fuel line is made for pipe threads myself. Jury is still out on this..but that is what I see from the photos given.

DUB

 

hmmm... looks like the threads line up. I can't imagine the threads NOT being tapered/NPT. Maybe goup it up and jam it in there and tighten awayl!

 

Yes, strange. I didn't think they made fuel line with gauge port in any other thread.
Or maybe someone re-threaded to different thread size.
So now I'm up for either invest in a new fuel line or skip the fuel pressure gauge all together or try to re-thread the threads in the fuel line.

 

Try this. Go to the hardware store and get a brass fitting that the fuel pressure gauge can thread into...then...take the Allen plug and see what happens if you try to install it in the brass fitting. If it locks up the instant you put it into the brass fitting...then something is obviously wrong.

If it did lock up. Then I would get out my tap and remove the line and thread it so I could install the gauge and not think twice about it

DUB

 

Yes, I'll go for that. Disconnect fuel line and redo the threads. Give it aatry and if it doesn't work then make investment for new fuel line.
Thanks for all the support!

 

Most tap and die sets come with a 1/8 inch NPT tap. T