What goes in this hole where I'm pointing a brake line to? It is between the #1 and #3 cylinders on the driver's side almost at spark plug level.

 

Coolant temperature sender/switch of some kind (if you application has one in that location, which all 3rd gens do). If it's an application which does not have a temp sender in that location for some reason, you plug it. It's exposed to the water jacket/coolant in the head.

Since the left and right side heads on a small block Chevy are the same you have the same thing on the pass. side head between 6 and 8.

 

I have both my sensors (to the tach and ecm) in the stealth ram base plate. Could I just plug up those holes i was referring to up top? Or does the placement of these sensors matter?

 

Your temp sender for your guage should go there and the hole on the pass. side is for your fan switch.
HTH

 

GM puts them in the head, but you could run it in the manifold. Some other vehicles run the temp sensors in the intake... I dont think there would be a whole lot of temp difference and its just for what is likely an inaccurate gauge anyway.

Plug the hole. Use a recessed hex plug, preferably. Dont forget some non-hardending sealer (not silicone!) or teflon tape!

 

I thought the ecm used the temperature sensor signal to send power to the fan relay... That sensor has 2 wires.

The sender I'm referring to goes to the instrument cluster. It has 1 wire and is grounded through the engine.

I'll either keep my 2 sesnors where they are and use a pipe plug between those cylinders or relocated a sensor to the correct locations and use a pipe plug on the intake. Thanks for the help.

 

There are 3 temp sensors on a typical 3rd gen V8:

2-wire temp sensor in the intake is the temp sensor for the ECM (which can control the fans on some cars, like TPI engines, but doesn't on others like with TBI engines).

1-wire temp sensor in the driver's side head that runs the temp gague in the dash and nothing else.

1-wire temp sensor in the pass. side head which is a fan control swtich. It is present even in cars where the ECM controls the fans just in case the ECM doesn't do it's job, this switch will save you from melt-down.