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my degree wheel has intake open/intake closed marked in red as well as exhaust open/closed marked.its also marked 0-180 then180-0.how do i know where btdc ,atdc etc are should i just watch the piston movement,thanks mike



It does get confusing , you just gotta count backwards , take a step back & figure where the piston is in relationship with degree wheel markings , you've come this far i'm sure you will sort it , as said , you are not alone regards the confusion with those degree wheels , if the maths is all funnky then check again , it will come good.