I must do it all wrong then, or because I do it while assembling the motor the valve cover is superfluous. On my motor:
Block on, locate a true TDC for #1 piston. Made a mark on the crank (points side). Installed head and cam/adjustable sprocket. Rotated the crank with degree wheel attached, recorded measurements. Reversed crank, recorder measurements. Did the math. Spun the crank until #1 was TDC (used a piston stop in #1 plug to confirm). Adjusted the cam on the sprocket. Locked it down. Rotated crank fully. Confirmed lift on the degree wheel with mark aligned. Installed cover, set valves. Took about 30' start to finish.
What am I missing? Is it because you don't have a true TDC on #1 or a piston stop and you're using valve tolerances on the rockers? If so, I get it. If not, I'm confused as hell...
Cal, here' s the clearest real world example I have. I sent myself an email with various degreeing tips to study quite some time ago. Whoever wrote this, sorry I never saved the name.
THESE ARE THE STEPS AFTER YOU FIND TRUE TDC WITH A PISTON STOP. The opening and closing number will vary from cam to cam depending on the specs. You can just plop your numbers in from the timing card.
"-set your valves to zero lash
-set up a dial indicator on one of the valve retainers. zero it with the valve closed
-turn the engine through, and when the dial indicator measures .040" lift, look where the degree wheel reads. continue turning through until you are back at .040" just before the valve closes.
-do the math with those numbers: O (open #) + C (closing #) + 180 /2 - S (the smaller of the two numbers.
-if you're off by a few degrees, imagine what a change in either direction will do on the wheel, then redo the math. note that when one numbers increases, the other decreases, as they are relative to different point of piston travel.
-pull the cam cover, move the cam in the desired direction, reassemble and remeasure.
-so if O=26 and C= 55 and (O+C+180)/2 -S (i'm pulling these numbers out of my ass) , then you would get: 26+55 +180= 261. 261/2 - 26= 104.5 (ok, maybe they weren't totally out of my ass, because that's what you want for your lobe center). if you wanted to see what one degree advance would do, plug in the numbers O=27 and C=54, and you get (27+54=180)/2= 130.5. 130.5-27= 103.5."