where would i put the sensor on the temp gauge? right now someone put it in the thermostat housing so it doesn't read until the car is already up to temp.
The water cross-over on the intake manifold is the most common place to mount a sending unit for water temp. If you are using a manifold that doesn't have a port for a sending unit you can remove the manifold and drill and tap a port in a convenient place.
If it is a 302 then put it in where the sending unit for the light is. It is located in the coolant crossover on the front drivers side of the intake manifold. Some temp sending units do not come with the adapter to mount it in the smaller hole and you may need to get one. Most parts stores sell them. If it is an I6 then it is located on the drivers side rear of the head. Same thing with the adapter.
On a 302, the sender is the 3/8 NPT hole on the drivers side and the heater feed line threads into the same size hole on the passenger side. If your outlet is in rough shape you could thread in a T-fitting for the heater core outlet and the sending unit and run the gauge but still have the light work if necessary. Some later intakes and aftermarket ones run a 1/2"NPT fitting on the passenger side. just use a bushing sized for what you're installing.
You can also get a water neck/thermostat housing that has the fitting for a temp gauge. Manifold would be ideal, but as you can see there are several options.
