I want to perform the air pressure test for VTEC activation and need assistance identifying the thread pitch of the fitting necessary to screw into the head for attaching the air line. It may be that one of the fasteners I am using for a trial fit has a slightly deformed thread or some similar issue keeping it from engaging properly.

It would appear to require a 10mm fitting but neither 1.0, 1.25, nor 1.50 pitch fasteners seem to engage properly and I can't see the teeth of a pitch gauge clearly enough to rely on it. Without knowing the correct pitch, I don't want to apply much tightening force.

73,

ASm