Where does it get the air to compress? Pulls a vacuum when the piston goes
down before the compression stroke.

wrote in message
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Bill McKee wrote:
. And my daughters Explorer broke the intake rocker and
zero compression reading.

How? Intake valve ALWAYS closed that way. So, when the piston comes up
on the compression stroke, both valves would be closed JUST EXACTLY
like they would be if the intake rocker wasn't broke.