I have an 89 Iroc z28 tpi and I'm putting a 350 sbc my problem is I don't know what the sensors are that are in the cylinder heads, one on both heads can anyone tell me what these to sensors are that are in the water ports?

 

One will be the coolant temp sender and other one is the elec. fan temp switch

 

One has a flat spade connection and the other has a connector like the knock sensor connector? The holes are like a 1/2 npt is what it looks like to me is that correct? Also I have the coolant sensor on the front of the intake manifold below the plenum is that correct also? I didn't take the old engine apart so when the guy I got the car from did all this he just stripped things off and didn't label any if the wires or sensors so I'm doing the best I can with a chiltons manual and google has been my friend through a lot of this along with the mounds of help that Brian at tuned performance has given me.
I genuinely appreciate all the help I can get.
Thanks a million for your time also!
Clint

 

the sensor in the driver's side head is for the gauge: should have a little nub on it that the dark green wire hooks up to.

the sensor in the passenger side head with a plug that looks like an oxygen sensor is the one that turns the electric cooling fans on.

there is a third temp sensor in the intake manifold by the thermostat housing, should have 2 terminals on it. that's the one that the ecm uses to tell the engine how to run..

all 3 of these holes are 3/8"npt, but if you have older heads from the 70's then they will be tapped 1/2" npt.

 

I appreciate the info that was exactly the info I was needing. Thank you very much.