I just took my head apart for repair, got everything back together...now when the car reaches temp, the rpms go up and down up and down... i seem to believe this has something to do w/ the coolant...from what i can see, it's not low, because i can still see the coolant sitting at the top of the radiator. any idea of what this could be?... thanks

 

sounds like a vacume leak. check all hoses and make sure your intake mani is not leaking.

 

I just checked all the hoses and even redid the intake manifold bolts w/ permetex layer on the gasket... still getting the surging...

if it makes any difference, the coolant i'm running is pure water, i'm just trying to flush out the system cuz some nasty stuff got in there when i was cleaning the piston tops....

also i'm running it w/o the radiator cap to let air bubbles out... but it doesn't appear that the coolant is even moving, it's just sitting in the radiator... any ideas? thanks