K341 exhaust pipe threads

[Hydros]

The engine block exhaust threads are NPT, tapered. The Kohler cast iron elbow is NPS, straight. My 1450 had a shower head muffler attached with NPT steel pipe (1” for the 1450 K321 as opposed to—I believe—1 ¼” for 1650 K341). Don’t know why they build them that way but maybe it’s because the Kohler EL needs to stop at just about 90 deg & can be locked there with that lock nut—that’ll work with NPS but not NPT--but there is a possibility of exhaust blow-by, I feel, with just one turn or so thread in plus possible stripping with only 1 turn or less of thread in. What worked for me was first cleaning the block threads with a wire brush then opening them a bit using an NPS tap--threads are exactly the same as the NPT. Lubing well with PB Blaster & turning in very small increments (1/32nd to 1/16th turn in then 1/4 turn out—repeating enough to get another two turns in with the elbow for a solid connection. Lubed it up with Permatex hi-temp nickel anti-seize & can get the EL at the proper angle & with absolutely no blow-by.

[TOPDOWNRESTO]

Thanks Hydros , looked like straight threads to me too. I borrowed a NPT tap and cleaned out the rust/ carbon in the block then picked up a 1 1/4 in NPT die. Worked it on by hand . It bottomed out quick but really didnt cut much off at all of the straight threads, however it did just enough to get me two good turns on by hand with no lube. I will try the stuff you used and see it I can get an extra turn from it ,maybe a wrench could get it good and tight, have the lock ring aas stated earlier.
Thanks for confirming my suspitions about the straight threads on the elbow.

Carroll

[Hydros]

What I did was the opposite, NPS tap to the block a few turns—not all the way in. That opened it up enough to get a few turns on the EL for a solid fit & able to align the EL with the muffler. That’s what worked for me but you need to proceed very slowly in small increments as I noted above—I would not put too much torque on that EL since it is not actually cutting as a tap would do. When it stops it means it is bottomed-out in the taper of the block so do not push it.
The NPT die might be too wide at the top to catch the first few threads in the EL.
Good luck…..
John