rc ign
did I mis-state something about the piston skirt and or its location if I did please show me so I can clear it up .
The piston skirt CLOSES the exhaust port .
please re read the entire thing I still dont see what you cant understand
its not a holley double pumper for crying out loud its a 13.5 mm zama .vacuum is what your refering to and yes to creat more vacuum restrict the venturi this however also restricts the amount of fuel and oxegen otherwise known as mixture that you can flow into the engine.
the thing with the floor of the port ,15degrees,and feeler gage was to give a sorce of reference to how to transfer degrees to measurment in a scale more familiar so during cutting we have a reference as to how much to cut it worked for me maybee I didnt explain it properly .I understand the top of the port controls exhaust timing thats why I told him to be so careful.did I miss something else if I'm wrong help me out I'd like to know to avoid passing bad info on to others.or explain myself better