Originally posted by Johnwalkeasy
The piston will be in the same position no matter what will it not?
absolutely not....the piston will always travel the same path, but changing timing will determine when the spark hits in relativity to the piston, it could change it from btdc to tdc or atdc, the goal really is to get combustion to happen before the piston starts traveling down but after the rod has changed sides on the crank journal, that way when the combustion happens, there is the least amount of resistance.... if we have it directly at true TDC then it would push directly down on your crank, if its btdc it'll push the crank the wrong way