>>
>>I think people are making a mistake here.  It is 180 degrees on the crank and 
>>90 degrees on the distributor.  Direction of rotation is unimportant.  Also the cam
>>lobes have a constant radius over their back end (away from the raised part of the 
>>lobe used to actuate the valve).  This means that the valve lash reading will be constant
>>for about 90 degrees either side of TDC (crank rotation) for the cylinder being adjusted.
>>
>>A. Burczyk
>>

You are right that it is 180 degrees on the pulley and 90 degrees on the 
distributor. But the direction of rotation is important. Beginning with
#1 valves, to get to the #2 you have to turn the pulley 180 deg counter-
clockwise. If you turn it clockwise and adjust #2 you are making a mistake.
If you turn the ignition, you will hear your pistons banging on valves,
and say goodbye to your engine. After adjusting #2 turn 180 deg counter-
clockwise again to get to #3 , another 180 deg for #4...

David Kao