I put these on my monte carlo last summer after reading the build up in the magazine.Now it seems like i am getting an over heating problem. I have the temp sensor in the pass. side head. Is this the  right spot for it ? I have a new 3 pod gauge kit I am going to be putting in .  

i have 84 monte carlo with a 450 hp 357 sb my sensor is in drivers side head.Dont think it will matter witch head the sensor is in.what t stat you running.I need a little more info on your engine and cooling system to help out.Is your compresion the same as before and are you making more hp.  

not sure what stat i am running i think it is a 195 and yes i am making more power it is the original 9:1 compression motor these heads put it at i think around 10:1 compression still has the factory radiator and the water pump mounted fan clutch style.
edelbrock carb and intake flowtech headers, and still have the factory shroud on it.  

Sounds like maybe you've got an air bubble in one of the heads that's restricting coolant flow. Aluminum heads dissipate heat quicker than iron heads. It oculd be the aluminum heads are keeping the top end cool enough that the thermostat isn't opening, try installing a 180-degree thermo and see what diffference that makes.

Also, what coolant mix are you running?  

i am running a 50/50 mix it usually gets up to about 220 at idle at stop lights in 85- 90 degree temps. as soon as i leave and get air to it, the temp starts to drop.  

i have the 84 monte stock radiator/ fan and water pump you need a 160 t stat.im running 10.5 comp. tha cooling system in that car is fine for what you are doing.also make sure tour carb isnt lean.160 t stat is key also make sure your coolant is circulating  

d-faria 1  your suggestion to go to a 160 stat was a great help it worked perfect. thanks to all you guys for readn' and answern'.