Installing temp guage sensor(aftermarket)

Charrlie_S said

Why not drill the cyl head? I have done it to several heads to use a mechanical temp gauge in place of the electric sender. Just enlarge the existing hole. Drilling to intake does no good, we are talking about a slant six, not a V-8. No water in the intake manifold. The t-state housing option has the problem, that the temp gauge will not show the temperature, untill the T-stat opens. If the stat does not open, the engine could overheat, and it would not show on the gauge.

Click to expand...

Sorry, I forgot the OP was working with a slant 6. Yeah, an intake tap won't work but I still would rather plumb a T in the heater hole outlet than drill the head. If something bad happens on the drill job, you may be looking at replacing the head. Of course, if you use the '75-up head, it has the big hole from the factory.....and hard seats to boot....
Oh, and if your thermostat doesn't have a bleed hole in it, get a different brand or drill one yourself. With the bleed hole working, you can get a decent signal for the temp sender in the thermostat cover. Not as good as one before the T-stat but better than one in the radiator hose.