When you get your Chilton or factory shop manual it will tell you how to do timing; I will give you a tip for '72, the marks on the balancer are for top dead center (TDC), 10 degrees before, and 20 degrees before. This is in the Chilton's manual, it's not in the factory shop manual. I thought it was 0, 4 and 8 degrees before but it's not. It'd be better to just find someone around you that knows how to time an engine; find and Oldtimer and have him show you rather than trying to explain it online. But here are some more tips. Also if you have a '72 your distributor is probably still points so you need a Dwell meter too. If it's a later engine in a truck being called a '72 then for all I know it has been converted to Pertronix (electronic ignition). Lastly if you really do have the '72 distributor it is a dual point and the timing changes by 4 degrees depending on where the clutch pedal and shifter are (at least it's supposed to). It was an emissions thing. Get the factory shop manual AND the Chilton's manual and have fun!
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