Question for Six Engine People, TDC and Z1 mark Options

[Robarabian]

I have a 911 engine I am working on. I am practicing setting cam timing so I can feel comfortable with it prior to the tear down. My Crankshaft pulley has a Z1 mark that has 2 lines. So I have seen 911 pulleys with Z1 and 1 line.

The question de jour is which of the 2 lines at Z1 is TDC? Or are the 2 lines giving me the dwell of where TDC is and if so, where should I put them in relation to the case to set cam timing and do valve adjustments.


it looks like " Z | | 1"

It is a 2.4


Somebody knows this answer.

[Robarabian]

So my pulley actually has the Z1 mark and the second line is after it. So I assume the mark after the Z1 is 5 degrees ATDC versus some of the other pulleys Ive seen with the mark before Z1 5 degrees BTDC.

You will see the sharpie thick line (that ends at a mark in the pulley) and the black from the sharpie in the Z1 line.


BUT... is the TDC mark the actual Z1 mark here?

Thank you to who chimed in, this is an assembled motor so I am not monkeying too much with things until I understand it all better. I am just trying to determine the current travel of the valve at overlap, which depending on the mark of this pulley, is 2.5 mm or 3.5 mm.

If Z1 is TDC, then the valve overlap appears to be 2.5 mm. Anyone have a chart with all the cam specs? I have Wayne's book and will dig through there to see if there is a chart.