I salvaged a fitting, barb to male taper thread. A 1/8" NPT 27 threads tap lines up perfectly with the fitting I just pulled. That's what I'm going to chase the threads with, using lots of teflon tape, and install 1/8 pipe plugs. I have lots of brass hex stock available, I'll probably just make my own plugs.

1 hour ago, emptech said:

I salvaged a fitting, barb to male taper thread. A 1/8" NPT 27 threads tap lines up perfectly with the fitting I just pulled.

Perfectly? That seems unlikely. It's odd enough that a British thread pitch would be used on a Japanense car in the late 60's/early 70's. Why would British be used on the block and US on the balance tube? Chaos!

Your thread chaser might cut some new threads though. People have used NPT in the oil pressure sender hole and made it work. Soft metal will distort.

2 hours ago, Zed Head said:

Perfectly? That seems unlikely. It's odd enough that a British thread pitch would be used on a Japanense car in the late 60's/early 70's.

Not odd at all. It's the same the same reason that British Standard threads were used on a "Japanense" car in the 1950s and early 1960s. Nissan's tie-up with Austin.

Wait 'til you hear about Imperial wheel diameters and PCDs...