GrandPaulZ· Super Moderator
Could be the pistons were changed without splitting the cases, so "never opened" (the bottom end)...
the sump plug.
Will either use a thread file or maybe obtain a unf tap and repair the face up.
I'd buy the new sump plug first, measure thread tpi and diameter on that before deciding what to do about the thread in the case - without being able to check a plug, it might be UNC, or Triumph used both UNS (Unified Special) and UNCP (Unified Constant Pitch) when a large diameter required a finer thread, or Triumph weren't even averse to retaining the odd British Standard (BSF?) thread on certain components ... :whistleI have time to play so to speak, before the bottom end gets put back together, so it wont hold me up.
Barrels go to the engineer next week,
'Fraid the seller is talking from an orifice other than the one in the lower half of his face ... 1"UNF is 12 tpi or 14 tpi (it's a long and boring story).new sump plug, The seller said it was unf.
I've found that its a 1''16 tpi and unf thread,