Air flow thru cylinder-2000 z28

[swifty]

In my cam swap process I am at the point of changing valve springs. I intend to pressurize each cylinder to keep the valves up when the spring is off. When I pressurize the cylinder by way of the spark plug hole, should the cylinder hold pressure? It does not seem to as I can hear air flowing, not sure from where. Even at very low pressure, like 20 psi, I can hear air flowing. Is this normal?

[RARON455]

What you are hearing is probably the air bleeding by the rings,, and going into the crankcase, You could pull the dipstick and see if you can hear/feel it coming out. I would expect some leakdown but I am not sure of how much is too much to be honest.

[c5z28]

Did you make sure the cylinder you are doing it on has the piston at top dead center?