Adjustable Cam Timing - 850R with N/A cams

[ojdorson]

When I put a new head from RSI on my '96 850R, I also installed cams from an N/A 850. At first, with the cams "time" in the center of the adjustable slots, I was getting terrible mileage - around 17 city/hwy. After talking with RSI some more, I ended up advancing the intake to about 4 degrees and things have improved. At my best, though, I was only able to get about 22mpg on an all highway trip. In the spring, I'd like to take the car to a tuning shop here around Chicago and have them adjust the cams on a dyno. I just don't know what the basic assumptions on adjusting the cams are, though. Like, advancing the intake cam should do WHAT, exactly? What about the Exhaust cam? Here and on VolvoSpeed, I've seen mention of a cam timing tool - best I can figure is a gauge that helps you see what degree you're turning the sprocket to - and that there are some settings for N/A cams in a turbo car that are a good starting point, but no one says what those initial values are!

Can anyone here school me on the adjustable cams and which way I should begin looking for the "Sweet Spot" on both the intake and exhaust cam? I'm sure others would find this useful and I really haven't found anything via search. I'd like to approach my tuning session with the most knowledge possible to minimize time on the dyno and cost.

[matthew1]

Volvo never published cam timing specs according to MVS Member tjts1, as found in this 850, S70, V70 Cam Advance/Retard topic. I'm going to lock this topic and send you over there so we keep what little we know about this in as few separate topics as possible.