Any good ideas what type of store might stock an 1/4-18 NPTF tap that I could locally try to source today (in LA)? I'm informed I need NPTF over NPT.

I'm drilling/tapping the temp sensor outlet in my '69 head for the larger 1/4-18 NPTF threads that '63 used. I have a good temp sensor and need to re-use it.

The usual suspects (Home Depot, Sears, Anawalt/True Value) have all failed me and I'd rather do this when the engine's on the stand, not in the car (which means I have to find it today - the engine is going back in today).

Anyone have ideas?

http://www.mcmaster.com/#pipe-taps/=o8093u

They aren't cheap, but if they haven't got it, you don't need it.

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Official Cookie and Mater Tormentor.

If you take the thermostat & housing out, you can stuff a rag in there and push it up towards the valves too then drill/tap. Been there, done that. Or maybe a small vacuum too aimed right under the hole.

I am pretty sure you don't need NPTF, usually automotive is just NPT. NPTF is a special-dimensioned version of NPT anyway. NPTF is supposed to give better sealing; I bet that the temp sensor you have is threaded NPT anyway.

I'd use NPT and use sealant on just the outer portion of the sensor (so there's still some metal to metal contact)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Oh! are you saying you can find 1/4 npt but not 1/4 nptf? Yeah, you can cross the two... F just means no sealant necessary, think the formal name is dryseal. Use whichever tap you find, put sealant on it, call it a day.