I recently swapped a 350 in place of my old 305. When i did this swap I also added headers, an old used edelbrock performer manifold, and a carb. Right now I have the temperature sensor sending unit in the drivers side water jacket in the head. After 5 minutes of driving, my gauge reads 250+. I think this is because of the fitting's proximity to the headers, because when I touch it it is extremely hot, and 5 minutes of driving in 60* temps shouldnt get it up to 250+ that fast. I figure the intake manifold will be a better place to put the fitting in light of this problem. I know of one fitting on the front drivers side of the manifold, but that is permanently sealed shut. Is there another point to place the temperature sensor? It seems that on my manifold there is a small fitting right next to the carb on the passenger side of the intake. Is this a water passage thru the intake? If not, how can i shield the sensor if it is on the head? Thanks for the help, sorry for the length.
Matt

 

No... that's the EGR\Exhaust Manifold Heat passage. Must be an old Performer. Newer ones have the front water crossover leg tapped for fittings on both sides of the manifold.

You could take the manifold to a machine shop and have the boss drilled and tapped ou. An easier solution would be to use a GM thermostat housing with two tapped fittings. Easy enough to find.

I can't see the headers affecting the Temp sensor in the head. They would have to be danged close. ( Just how close is it? ) Anything is possible I guess. More likely is that the wire is shorting or that the sensor may have been damaged on installation. Sensors are cheap. try a new one.

Best solution would be a good set of Mechanical Water and Oil Temp guages such as AutoMeter. Drill and tap the Manifold water leg on the the drivers side and install the mechanical sensor there. Use the Factory Water Temp and Oil pressure as a backup.