Theoretically, you don't have to do anything with the cam. Just go to TDC with the cam mark aligned (that will be TDC on the compression stroke). Go another 15 degrees. That is where the IP should be timed. Remove the IP, turn it so the tang is centered in the port, install it, and you should be good to go. HOWEVER... there is more to it than just that (of course).

1. I'm not sure if there is anything to be concerned about regarding the timing device and the vacuum pump cam. I'd have to look at the manual, which I do not have here.

2. When you remove the IP, you are supposed to use a special tool called a "centering tool" to hold the pump sprocket in position while the pump is out. I improvised something myself, but I don't want to risk the wrath of the paperweight police. You should get the manual (it is available online at a few places) and study it. I saw the centering tool on ebay for $10 or something really cheap like that.

3. When you remove the IP and set it so the tang lines up, you will need something to hold in position when it is installed. There is a special tool that goes into the port and engages the tang to hold the IP cam in the right position. I made a tool to do this, but once again... there's that whole paperweight issue.

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1987 W201 190D