TDC - crank pulley and rotor disagree !!??

[Decolliber]

Re 88 Carrera.
Preliminary to trying my first valve adjustment, I set out this AM to make sure I could get all the right positions on the rotor and crankshaft pulley. Following Bentley and Pelican tech article on valve adjustment, I started by setting the distributor rotor on the the mark on the housing. The rotor can be moved slightly clockwise (against the spring) but I assume I should use its resting position. But at this position, the Z1 mark on the crank pulley (the right hand one of the two notches when behind the car, facing front) is about 30 degrees off to the right (clockwise) away from the marker on the fan housing and the crank case seam. My first thought was that the distributor housing has been installed incorrectly, but Bentley (102-36) says there is only "one way" to install it.
I have no idea what to do.

[rstoll]

Try going around again.

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Robert Stoll
83 SC
83 944

[Bill Verburg]

There are 2 TDC's in a 4 stroke cycle, one at the end of the compression stroke and 1 at the end of the exhaust stroke.

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Bill Verburg
My Home Page My Pelican Gallery page My Porsche Owners Gallery Page

[Rod Walter]

John, the Bentley manual is inconsistent in which mark on the pulley it says to use. You should actually use the left of the two marks on the pulley, not the right. If you check you will find that the left mark is the only one that is 120 degrees away from either of the other two. The right mark is for timing and is so many (I forget the number) degrees BTDC.

If you look carefully at the top picture on page 151-2 in Bentley you will see the left mark designated as Z1 and the other mark is visible to its, well, right!

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Rod Walter
'88 911 coupe

[This message has been edited by Rod Walter (edited 09-23-2001).]

[john walker's workshop]

the TDC notch that relates to #1 and #4 (Z1) is the only one of the three TDC marks around the pulley that has another notch to the right of it. it's for the timing light to see if you get full advance as you raise the RPM.

[Decolliber]

Thanks for the help!
Now that I am using the left hand notch, and the right side of the rotor (not the centre line), the two TDC indicators match. I cannot see any Z1 mark because of the A/C pulley. What threw me off was first the error in Bentley (p. 102-35 shows Z1 as the right hand notch), and second, the Pelican tech article "911 Valve Adjustment Made Easy", in which Fig. 12 shows the Z1 mark as the most right hand mark of three notches.
Am I supposed to see 3 notches? I only see 2.

[Superman]

My pulley has a Z1 mark, and a 5-degree BTDC mark just to the right. I wish it had a 'full advance' mark at 28 degrees or whatever, but it doesn't. I should give it one.

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'83 SC