Diecast18

Hi guys, I'm in the process of adjusting the valves on my 911, but I made a slight mistake. I removed the distributor from the car whith the engine at Z1 mark. Now, I'm not sure if it's at top dead center for cylinder one or for cylinder 4.
The following description is based on the position of the engine with respect to the Z1 mark:
First CheckUp:
Intake Valves on Cylinders 4, 5, and 6 look raised at about the same level
Intake Valve on Cyl 1 is high, Cyl. 2 is low, Cyl. 3 is high

Second Revolution or 2nd Z1 mark check up:
Intake valves on Cyls. 1, 2, and 3 are raised at about the same level
Intake Valve on 4 is high, 5 is low, and 6 is high.

Based on these two check ups. Which position would be TDC for Cyl. 1?

You answer to this question is appreciated.

Steve Wilwerding

Is the distributor pointing to the notch in the housing? If so, cylinder 1 is at TDC. If not, cylinder 4 is at TDC.

Howard

Of course at Z1 both cylinders 1 and 4 are at TDC, however, the rotor must be pointing at the cylinder which is on a compression stroke. So the valve that is closed, either 1 or 4 is the plug wire on the distributor cap that the rotor must be pointing to for a static rough timing setting.
The valve spring would be relaxed for the cylinder on the compession stroke, compressed when the valve is open.
Hope this helps.