Originally posted by Cummins Corvette
Don, Chris, it's ok. You're both right, but can't understand eachother's way of saying it.
Don says- the plunger advances the timing at idle... .
Chris says- the plunger retards the timing at anywhere but idle...
What niether of you are working out is weather the timing spec is for degrees of advance when the "protrusions" are in-line with the ports, or when the "groove" is in-line with the ports.
I think that would be something worth finding out. We know the specs are different between the the 215 pumps and the others.