Not certain about the WD 45 but I think it's the same as my WD. Remove clutch inspection plate on bottom of flywheel housing. Turn engine until #1 piston is on compression and then look for the letter F stamped on the flywheel to be near the center of the inspection plate opening. This is sort of an eyeball thing cause there is no real mark to line up the F with except your interpretation of the "center" of the opening. You may have to clean off the flywheel some to see the mark and it is not real easy to see. A bright light helps. Once you have it "eyeball" centered proceed with the mag or distributer timeing as the manual states. I have mag ign. I found the tricky part is lining up the gears in the mag. Not difficult, but not too clear to me in the manual.