O.K. while replacing the head gasket on my 95 850 which was a success by the way, I noticed that after you pull off the outer large black plastic cam belt cover you're left with the smaller inner cover that bolts to the cam-valve cover. This smaller cam belt cover has some timing marks in it above the intake cam. I have the chilton and Haynes manual and neither makes any mention of these marks and what they are for. I'm guessing maybe its a way to slightly alter the distribtor timing as the cam spockets have slots in them for adjustment. Can any body shed any light on this. Do you hook up a timing light or what?

erobb

 

I have seen them for Years and if I remember correctly they even have #'s by them.

But have never researched to see what for.
I always just use the Marks for the Line up.

 

Sounds to me like you're describing the adjustment for valve overlap ( vs. spark timing)
There is some performance to be gained by changing valve overlap, but you must know what you're doing....

 

When I was searching the forums some time ago there was a thread that mentioned adjusting the ignition timing for maximum power as well as maximum fuel economy, but didn't go into detail as to how it was done. Since the distributer cap is non movable in the sense that it screws directly to the head, the only way of adjusting the timing would be to loosen the cam sprocket bolts and move the cam one way or the other to advance or retard the timing within the slots on the spocket. I agree that it would change the valve timing as well. Still diging for answers, those marks are there for a reason.

erobb