Testing Oil Pressure with a Comp tester?
No I would guess your last is a photo of a 10mm plug thread. These were used for a very few years in old Chivvy 6's (216s?) and Pontiac straight 8's at least.
But with that gauge being one of the "lucky" ones with a standard series air fitting, it's no big deal to buy a matching coupler and simply bush it down to 1/4 or 1/8 pipe as required.
I was amazed, back in my HVAC/R days, the first time I tore into a Lennox Pulse furnace, to find that a modified version of a 10mm plug was used as a flame sensor!!!
(In fact the ignitor actually IS a spark plug)
No I would guess your last is a photo of a 10mm plug thread. These were used for a very few years in old Chivvy 6's (216s?) and Pontiac straight 8's at least.
But with that gauge being one of the "lucky" ones with a standard series air fitting, it's no big deal to buy a matching coupler and simply bush it down to 1/4 or 1/8 pipe as required.
I was amazed, back in my HVAC/R days, the first time I tore into a Lennox Pulse furnace, to find that a modified version of a 10mm plug was used as a flame sensor!!!
(In fact the ignitor actually IS a spark plug)
