Maybe I misses a thread in my search, but I can not find this info. I have a new modulator ready to install. Old one id out, car in stands. This is a newer black style modulator.

The new one has a "key" that goes in first, followed by the cap. The key is the interface to the cap that turns. What I am wondering is what position the key should ideally be in before I pop the cap on? Since the cap will stop at the vacuum port I am limited in how it can be turned.

Concern is that the valve is setup as a screw type closure. What I mean is that there is a huge variable in adjustment as the center screws in or out to change a gap. Or if its a ball type, then it really does not matter as much as each revolution opens/closes it again.

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1991 560 SEL / 185k miles
1992 750il / 17k miles - project car