Best way to check if the timing Z1 mark is off?

[beschouten]

I think my timing mark is off, a previous owner had replaced the chain tensioners and it runs bad if not significantly advanced at idle. What could I do to see if the timing position is correct? 79 SC

[Scott R]

Well the timing mark/pulley is keyed to the crankshaft, you would need to check the cam timing individually.

[beschouten]

Could I tell enough from having the valve cover off or am I talking about taking the motor out? If the cam was shimmed how could I tell?

Thanks in advance!

[timmy2]

Pelican Technical Article: Setting and Adjusting the Cam Timing - 911 (1965-89) - 930 Turbo (1975-89)
Wayne's rebuilding book helps a lot too.

[beschouten]

Originally Posted by timmy2

Pelican Technical Article: Setting and Adjusting the Cam Timing - 911 (1965-89) - 930 Turbo (1975-89)
Wayne's rebuilding book helps a lot too.

This is exactly what I'm looking for. I'll look for the valve lift overlap "intersection" on both cams and see if it aligns with Z1.

Thanks!

Brian