if your playing with cam timing and wish to change it a few times, you are best to buy the custom made timing case as well.instead of pulling the sump and timing case off every time you what to change the cam timing.you only need to set cam timing once(refer to your cam specs), but you can play if u wish (comes back to cost of adjustable gear and timing case)if you can get it right the fist time its all good. cheers ernie