If you haven't put the head on yet you can set #1 piston to top dead center by truning crankshaft with wrench until piston stops rising & jsut before it starts descending. This is TDC but you won't know if it is on compression or exhaust stroke. Install the head and rocker arms, if both valve springs on #1 are loose it is at compression stroke and follow the instructions for setting both Intake & Exhaust on #1, Exhaust on #2, & Intake on #3. If one of the valve springs on number #1 are under pressure then set clearance on #2 intake & #3 exhaust, put a mark on the enging front pulley and rotate crankshaft 1 full revolution and set the other valve clearances.