Intake valve leak question

[Lugnutz65]

Question: other than the intake valves, are there any other passages that can leak air pressure from the crankcase and up through the heads into the intake manifold?

I’ve established considerable blow by in cylinders 2, 5, and 8 using a professional cylinder leak test gauge.
I have rockers completely loose so the valves MUST be closed during the test. When I add 100psi to the cylinder I definitely feel and hear air flowing at the oil fill cap. The intake manifold is properly sealed to the heads. I know that passages in the head allow drainage of oil from the head to the crankcase but to my knowledge none of them would communicate with the intake or valves unless the valve seals were bad.

Comments?