If the motor has solids, this is how I set them:
Engine hot/warm and off: Line up the rotor in distributor with a sparkplug tower on cap. This is the cylinder which is about to fire, and both valves will be closed. Set the intake and exhaust clearance on that cylinder. Then bump motor over until rotor lines up with next sparkplug wire on cap. Then set the intake/exhaust clearances for that cylinder. Follow rotor around firing order until you set the valves for all 6 cylinders. That way you know you set the valves when they are closed. It is imperative that you set the clearances with the lifter on the "base circle" of the cam lobe in question when the valve is closed.
If you back off on an adjuster and the valve/valvespring starts to move, then that valve's lifter is not on the base circle (seated) and that valve is still open. (unless you had the valve set way too tight the last time.)
What do the books say to set the clearance to? For a stock cam, try .010" on intake and .012" on exhaust. More clearance if aftermarket cam. May clatter a little more than stock, but you'll know that the valves are closing and the slight extra noise won't hurt anything besides your ears.
