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I have been scratching my head for over a month over the AN fuel fittings, and their threads. I have not had any problem with the flare fittings, but the pipe thread side going into AN867 threaded bungs and the brass fuel tank strainers have been giving me a hard time. My assumption was that the aluminum AN867's had distorted due to welding, or were purposely undercut so that the builder could cut the threads to suit. But the brass strainers I would have thought should be cut properly. I haven't tried to cut the 867's yet, but have cut the threads in one strainer fairly deeply. I also ran a die over one AN6 nipple and cut those threads very deeply. Doing that allowed me to properly seat 1 AN6 fitting in a strainer.
Without doing this I could engage 1 thread by hand, and then the second thread with a wrench. By the time I had the was 2 threads deep, I am at 3 times the max torque for an AN6. NPT threads should only have 2-3 threads proud of the joint when torqued. The fittings will be destroyed before I get 1/3 that deep.
Just for the heck of it, I took a new, untouched strainer, and AN867, to the local hardware store. I took a 1/4 NPT brass fitting and threaded it into both the brass strainer, and the AN867. Perfect fit on both. So it isn't the strainer, or AN867, it is the AN6 fittings. That surprised me. I assumed it was the brass strainer and 867.
I will often run a tap through a hole to make sure the threads are good and clean, but to make the AN fittings work, I would have to deeply cut the threads on both the strainers and AN867's on the fuel tank. VERY deeply cut the threads. Is this normal?
Every AN6 pipe fitting that I have feels exactly the same. I can get 1 rotation by hand.
Without doing this I could engage 1 thread by hand, and then the second thread with a wrench. By the time I had the was 2 threads deep, I am at 3 times the max torque for an AN6. NPT threads should only have 2-3 threads proud of the joint when torqued. The fittings will be destroyed before I get 1/3 that deep.
Just for the heck of it, I took a new, untouched strainer, and AN867, to the local hardware store. I took a 1/4 NPT brass fitting and threaded it into both the brass strainer, and the AN867. Perfect fit on both. So it isn't the strainer, or AN867, it is the AN6 fittings. That surprised me. I assumed it was the brass strainer and 867.
I will often run a tap through a hole to make sure the threads are good and clean, but to make the AN fittings work, I would have to deeply cut the threads on both the strainers and AN867's on the fuel tank. VERY deeply cut the threads. Is this normal?
Every AN6 pipe fitting that I have feels exactly the same. I can get 1 rotation by hand.
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