What exactly is "checking clearance"? I may be misunderstanding the term. As I understand it, it is the amount of lift on the cam at which angular crank measurements are recorded. In this case (based on Paul G's data) I should see the crank at 18 BTDC when the intake cam lobe is providing 0.010" of lift... and 58 ABDC when the closing intake lobe is providing 0.010" of lift.
I do not have my Excel data with me at work. However, I do remember looking at this and found for 0.010" of lift the crank was at about 19 and 57 degrees respectively which is close to Paul G's data and probably within measurement error for such low values of lift.
With max lift occurring where it should be (110 ATDC and BTDC for intake and exhaust respectively) I'm not sure where the 4 degree advance on the overlap point is coming from. It suggests that the duration is not what it should be or that one or both lobes are worn or not symmetrical. But how would I know or measure it more accurately? I may try moving the indicators to valves 1 & 2 and repeating the measurements tonight.
I also may put the old paint marked original pulleys and chain on this evening and look at where the crossover point is with those components. I doubt it will be much different but maybe I will gain a better understanding of what is going on.
You said: "For the setup I would use opening/closing points, if they = 110 lobe center."
Can you clarify what you mean?
Doug L.
--Previous Message--
: OK if you go by opening & closing
: points, at specified checking
: clearance, what is the LC?
: The number difference sounds like 4
: degrees advance in the grind. The
: difference between the lobe separation
: angle & lobe center is the
: advance/retard ground into the cam.
: For the setup I would use
: opening/closing points, if they = 110
: lobe center.
: Glen