Timing Mark change
...............how much offset in degrees or inches there is between the passenger and driver side marks......................I found on BHS that the Driver Side timing mark is 7° CCW from the key..................... the offset from the key for the Passenger side mark, that would allow calculation of the total distance between the two marks.
PLEASE FORGET this sillyness
POINT numba ONE. You do not know if the current mark is correct
POINT nubma TEU. RE-read point numba one
(I'm 64 and have pretty bad arthritis. I can still do this procedure in less than 45 min. on an A/ B body on a good day)
PLEASE buy, make, steal, obtain, a piston stop, it will take you FAR less time to do this right with a piston stop and then you will KNOW the mark is on
Piston stop:
https://www.google.com/search?tbm=i....0.0.0.0.166.1509.3j10.13.0...0.0.hVCS91ws7nQ
http://www.jerrybramlett.net/images/pic_installation.jpg
Remove the number one plug, make sure the piston is "down a ways" and remove the battery ground for safety
Install the device. You may need to adjust the length (NOT critical) the first time you use it. You are NOT trying to stop the piston at TDC, but rather with the piston 'down in the hole' some amount
Wrench the engine around until it stops on the device. Make a temporary mark exactly under TDC on the timing marker.
Rotate the engine CCW, until it stops again. Make a second mark, same as before
You should now have two marks some distance apart. Exact TDC will be halfway between the two marks, and THAT is the end