in need of help
they will air lock so make sure it has burped and is truely full.
check the cap w\a pressure tester none availible? buy new.
another possibility is a radiator not flowing enough at high rpms with the new elec w\p.
water comes into the w\p at the thermostat and out at the upper hose if the radiator is not up to snuff it could create enough pressure to lift a good pressure cap.
hope this helps. just some ideas before you get pissed and rip the heads back off.

