The best way to install the chain, is the MB way of rolling the chain in connected to the old chain.
By doing it that way you won't need to worry about the pump timing as it won't change.
MB offers a tool for about $25-30 that holds everything in place while rolling in the new chain. MB part # 602-589-01-40-00.
The best way to time the pump is with an "A-B" light, by locking the pump with the tool you will get the timing with-in 3-4 deg. & that isn't close enough in MOST cases!
MERCEDES Benz Master Guild Technician (6 TIMES)
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)