AN6 fittings with mechanical fuel pump

[Steinerj56]

I recently installed my rebuilt engine and am looking at finishing touches. I bought a Jeg's fuel pump and a straight 1/4 NPT to AN6 fitting. I installed only to find out when I installed it the end that went into the fuel pump stripped out. The aluminum came apart and was leaking when just sitting with out engine running. Threads were gone. I thought about trying to run a tap but since it was fuel related I decided it was best to just replace. I ordered one from Summit to see if it was any different. Look almost identical. Bought a Russel brand fitting also.

I started to finger tighten and found it only went in about 3 threads before it got tight. almost the same as the original. I am using a brass barb hose fitting on the inlet so I installed this and found it went a little further. I cleaned threads as best as possible and the AN fitting only went a little further. The whole threaded portion is approx. 1/2 inch deep and I am only going in about 1/4 inch before it gets tight. Before I throw away another $45 and buy a better brand fuel pump do you have any thoughts or ideas how to make it work better? should I use a non hardening sealer like permatex #2? Or just get it tight and see if it leaks?