Hey guys. My car has both a pressure sensing radiator cap and a thermostat valve on top the intake manifold.

Do I need both? One or the other? If so which is best.

My engine runs very cool so I would not mind heating it up a bit to dispell and water vapor/condensation in the fuel oil system.

Thank you in advance.

It is the thermostat that determines how fast the engine warms up t operating temp, and the operating temp..
The stock water cooling system is way over built, and if in good condition can run a sb as low as 140 Deg with a low rated thermostat....hence why the stock thermostas where 190 degs.

Having the system under pressure increases the boiling piont of the water (so does the anti freeze but lets put that to one side for now)....Althu the temp gauge reads say 190..it is possible under certain circumstance to have parts of the colling system get close to or above 212 deg....rather than boil...the water keeps its liquid state.
Chevies then to have high pressure caps...12 to 15 psi.

Before increasing the temp spec of the thermostat....check temps with another thermometer......and check that your thermostat has not jambed open.

If you're talking about having a radiator cap on both the radiator and an aftermarket thermostat housing ?? Typically the cap that is highest is best in theory.
However, if it's on a typical 1st gen, just the radiator cap on the radiator will do just fine.

You have something like this?
http://www.summitracing.com/parts/CSI-913R/?image=large

I am new at this but I took the thermostat housing off the intake manifold and it was empty. Put in a 190 degree thermostat and promptly blew the heater core. Just figured I did something wrong by putting one in.

Put in a 190 degree thermostat and promptly blew the heater core.....Just figured I did something wrong by putting one in.

Nope...the heater core would have been suspect to start with...
did it blow the core or where the pipes are soldered in?

I rerouted the coolant. I was going to tear into it but thought, heck I was going to put AC in anyways so why fix it now. I am in S florida so not much need for heat here.