I have a ZZ4 with about 20,000 miles on it. the motor has set for about 4 years. I'm getting ready to install it and fire it up. While still on the engine stand I thought I would prime the oiling system. #5 exhaust rocker is not oiling. So I pulled the rocker arm and push rod to blow air through. The rocker was clears and the pushrod had some oil in it but it still does not oil. I'm using a primer shaft with a 800 rpm drill. The guage shows 50 psi. Could it be a lifter fouled and if so will it pump better with the engine running? Or do I dig further?