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Valve Adjustment Manual Misprint - Help Please!
Posted: Tue May 13, 2014 8:18 pm
by Jim Ed
Why does the orange Volkswagen Official Service Manual Super Beetle, Beetle & Karmann Ghia: 1970-1979 say to adjust the valves by rotating the crank pulley 90 degrees counterclockwise and all of the other manuals that I have read say to rotate the crank pulley 180 degrees?
Is this a misprint?
Thanks In Advance!
Re: Valve Adjustment Manual Misprint - Help Please!
Posted: Tue May 13, 2014 9:15 pm
by Marc
90° makes sense if they are referring to the orientation of the distributor rotor, not the crankshaft. Since the distributor rotates at one-half crankshaft speed, 90° movement of the rotor equals 180° movement of the crank/pulley.
Personally I don't bother with removing the distributor cap to see where to position the crank for #1 TDC. Simply rotate the crank until the TDC mark is up, then go below and see whether it's "on" #1 or #3 by observing the position of the rocker arms. If you're on #1, #2 exhaust will be the only valve open on the RH side; if on #3, only #4 exhaust will be open on the LH side....whichever one's ready, adjust its valves and then move on following the firing order, rotating the crankshaft 180° clockwise each time as you go from 1 to 4 to 3 to 2 (or 3 to 2 to 1 to 4).
Re: Valve Adjustment Manual Misprint - Help Please!
Posted: Thu May 15, 2014 8:07 pm
by Jim Ed
Marc wrote:90° makes sense if they are referring to the orientation of the distributor rotor, not the crankshaft. Since the distributor rotates at one-half crankshaft speed, 90° movement of the rotor equals 180° movement of the crank/pulley.
OK. It makes sense now. I must have been not fully focused when I read that.
Adjusting the valves according to the position of the rotor would be quite helpful to those without a degree ring crank pulley.
Re: Valve Adjustment Manual Misprint - Help Please!
Posted: Fri May 16, 2014 1:09 am
by Marc
Jim Ed wrote:...Adjusting the valves according to the position of the rotor would be quite helpful to those without a degree ring crank pulley.
It's not particularly precise - you're probably going to be within ±15-20° of the desired crankshaft position, but that's close enough. But if the distributor was installed incorrectly it'll cause all kinds of confusion for someone who isn't savvy.
Every stock pulley has at least one timing mark (if not a TDC, there's a 5° ATDC and/or a 7½° BTDC at minimum - again, close enough for the task) radial lines and a couple of holes in the face. More than enough reference points IMO to estimate a half-turn without a degree wheel, but some still like to make a paint mark 180° from TDC.