Just checked the fuel tank outlet on my Maxwell and a 1/2 x 20 tap fits it perfectly. Is there pipe fittings this size or is this another part I need a machine shop to custom make?
Hello Howard. I'm guessing it is a 1/4-18 NPT. A tapered pipe thread would seem appropriate there. I checked my '15 Maxwell tank and it was 1/8-27 so they appears to be different.
1/4" pipe is a little over 1/2" (.540)
1/8" pipe is a little over 3/8" (.405)
Thanks for the help Richard. I'm pretty sure your right. I found another site with someone asking the same question pertaining to smog plumbing on exhaust manifolds and they came up with the same conclusion so I guess this will be a part that I can buy at the local auto parts store....for a change!
While you were posting I got off my.....chair and measured the other tank. 1/4 NPT fit nicely in it. Also shown is the earlier tank with a 1/8 plug.
Remember that most pipe threads are "taper pipe" The hole is a taper and not straight thru like a bolt thread. Do not run the tap in any more than needed. Do not cut new threads. I think most taper thread taps are designed to only use about 1/2 of the threads on the tap to be the correct depth. But that could vary with different tap manufactures.