I'll have to check the plugs tomorrow after work. If the head gasket or block/head has a crack, it has to be extremely small since there is no hesitation driving the car and zero smoke. What are the chances the coolant is leaking to somewhere outside the head letting air in?

 

With these tiny leaks it is almost always the metal ring in the head gasket between the coolant passages and the cylinder. I have been tricked in the past when I jumped to the head gaskets conclusion to fast and it was an intake leaking into the intake valve, One that is pretty rare and two it would not cause the coolant pressure increase.

Cracked heads and cracked blocks normally follow major overheating events. Anything is possible but odds are it is just the head gasket.

 

I suppose the upside to this is if it is indeed the head gasket, it will give me a chance to clean up the engine bay a little.

 

I don't .blame you abit for you but after what I been seeing on craigs list up hear ,2 z28s running for under 1000.00 ,one blown head gasket ,other tranny shift issues,but I seems one could turn these car ,if you have the time an place to do it ,an the ones I seen the bodys look .great shape ,so many extra parts to ,now I see .whygorn has 4 of them hehehe