I have a 1972 sbc 350 that I've rebuilt with the same old heads, (520's). Later, I replaced the heads (487's), and cam. My problem is that I have ~0 oil pressure with the engine running and in gear waiting at a light. When the light turns green and I start going, the pressure reads normal to the rpm. I have a high volume oil pump and fresh sae 30 wt. oil. In short, I have a low oil pressure reading when the motor is hot and in gear, (195 - 210). This problem surfaced after the cam and lifter change. The cam is a Comp cam with 442/465 lift - 465/469 duration.