Originally posted by Streets
.. IT'S SUCKED INTO THE CYLINDER BY THE PISTON GOING DOWN WHILE THE INTAKE VALVE IS OPEN..
'nother iggy ..
Streets true... To add-if we take into account that for every action there is an equal and opposite reaction, hence vacuum-- nature's abhorrence to fill a void.

Excuse / I digress--We had an individual in our shop that many claimed " could pull a 27" vacuum on an onion sack." .. sorry