I checked my radiator temps

[procharge94]

I was trying to trouble-shoot for a cooling problem in my '94 GT, so I took the temp directly in the fill neck. I was making sure my temp gauge was somewhat accurate. Ever since I installed my motor mods(heads, cam, intake, etc.), I have not been able to keep a consistantly cool water temperature. The temp I was reading started around 160 and rose to 200 within about five minutes. This allowed me to eliminate a faulty thermostat from the equation. The head gaskets are also only a few weeks old, but this does not mean they are not the underlying problem. In addition to my confusion, my oil pressure has also been pegged out at max. So much so, that my valve covers are now starting to leak oil!! I am lost as to what I should look for next. Suggestions and advice are what I am looking for right now.