Inlet manifold, banjo bolt. What is correct thread (?BSP, NP)?

[chrishawley]

Current task is a Vitesse inlet manifold. So, where water flow through the manifold is concerned, that's the threaded banjo bolt on the rear and a threaded tail on the front.

Have managed to extract both without terminal damage to the threads but they need a clean up with a suitable tap. What thread though? Any advice? Its 14tpi which would fit in with either 1/2 in. BSP or NP 1/2 in. Thw males threads that came out look to be parallel rather than taper. OPs manual just say '1/2 inch' so that leaves me in the dark. Can anyone give a definite on the females for BPST v BSPP v NPT v NPS?  (Or anything else for that matter)

Thnx

[PeteH]

HI

Historically, "our" cars where manufactured during a period when some changes in standards where taking place. My best guess is likely 1/2" BSP. 55 degree thread form, ( the existing standard during any design phase), and still in common use. The tap will be "straight", aprox 19mm (0.7480") drill size, any taper being on the fitting. The common "giveaway" is the need (or not) for a base seal washer usually copper.?

Pete