Fuel tank drain plug thread

HELLO KELLY! I SAW YOUR PICTURES OF THE REBUILD OF YOUR BLACK PANTERA! REALLY NICE WORK! THE BEEFED UP WINSOR LOOKS OUTRAGIOUS! I KNOW IT'S VERY POWERFULL! YOU BUILT A MACHINE WE'RE ALL PROUD OF! WELL DONE MISTER!! ABOUT THE FUEL TANK; ALL I KNOW IS: THAT THE LITTLE PLUG ON THE TOP, (SOME TANKS DON'T HAVE IT, MINES A '74 AND DOES) IS A 1/8" NPT, SO MAYBE YOUR LUCKY ENOUGH THAT THE BOTTOM PLUG WOULD ALSO BE NPT. I DON'T KNOW, I TRIED TO UNSCREW IT IN THE PAST AND IT WOULD HAVE TAKEN SUCH GREAT A TORQUE TO DISLODGE IT, THAT I STOPPED IN FEAR OF "TEARING" THE SHEET METAL. IF YOU WERE TO FIND THE CORRECT FITTING FOR THE BOTTOM PLUG, THAT IS WHERE I WOULD PUT THE NEW PICK-UP FOR FUEL. IT WOULD CERTAINLY NEVER BECOME UNCOVERED OF FUEL! MAYBE USE A 90 DEGREE (SINCE THE LARGER DIAMETER WOULD NOT BE THE RESTRICTION OF A SMALLER SIZE; AND THEN, OFCOURSE, RUN IT FIRST THING, TO THE FUEL FILTER. THAT SHOULD GIVE YOU ALL THE FLOW YOU WOULD EVER NEED. REGARDS, MARLIN.

There are two sizes used for the bottom plug. Mine is a 22mm x 1.5 pitch. It is slightly larger diameter and finer thread than a 1/2 NPT. I dont remember what the other size is, but it is also metric.

Depends on how 'finished' you want the assembly to look, and which year Pantera you own. The '71-72 cars had a fuel-out pipe that was welded in place with a banjo fitting up top. The '73-on cars had the fuel-out pipe integral with the gas gauge sending unit. These senders retrofit into the old tank, providing a clean, neat fuel return but are expensive. A couple of years ago in PI magazine, I desribed a home-made mod that added such a line, in 3/8" size, to the early Pantera sender. This size supports at least 500 horsepower (the stock small size is only good for about 400), and has now survived 2 yrs & 3000 miles in our '72 Pantera, with no leaks. Adding a fuel-anything to the tank drain plug is IMHO, wrong mechanically, ugly esthtically and amateurish. Anything hanging down from the tank bottom is very vulnerable to road trash hitting it. This could break the dangling fitting collection or crack the thin tank bottom, resulting in an engine fire, as the headers are only inches away & airflow is up toward them at that point.

THE BOSS KNOWS BEST!! ANYTHING HANGING DOWN FROM THE GAS TANK IS SUBJECT TO BEING SNAPPED OFF! MARLIN.