the p79 head on my engine build has a 2-wire temp sender at the back on the plug side.

the car is a '78, but will be set up with su's so no ecu.

 

question is: should i use the head-mounted 2-wire sender or the T-stat mounted one for the gauge in my dash? if so, how do i wire it?

I would just continue to use the one wire bullet type sender up in the thermostat housing.

 

It's been a while since I looked at the numbers, but I believe the temperature profile for the 2-wire sensors is way wrong compared to what the gauge needs. Getting the gauge to read accurately using that other sensor would be difficult.

cool - just as i thought. that will make things simpler for me as well (always a plus) since i can just poach the sensor from my current motor and pop it into the new build.

thanks for the reply!