degreeing a slant camshaft with no cam card

Here is where I am at so far along with a few questions. When you have the time.

Quote: If you map out the cam, you see that the Intake valve opens at 6° before TDC and closes at 42° after BDC. There is 180° of rotation to get from TDC to BDC. So you take the intake open and intake close specs and add 180 to it to get the duration.

6 + 180 + 42 = 228°..........End quote

I am clear on this, and too add to it I am clear that valve duration is obviously how long the valve is open and yes this is the same spec that they give below of intake valve duration, you have shown me how they came to this conclusion.

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Quote: Now to find the centerline of the intake valve, divide the duration in half and subtract the intake valve open point.

228/2 = 114°


Now subtract the intake valve open point:

114-6 = 108°


This is 108° AFTER TDC. End quote..............

You say now to find the centerline of the intake valve.....would another way of putting it be now to find the center of the intake lobe?

You say this is 108 after TDC......why would we not start the degree count from the 6 degrees BTDC since that is where the valve starts opening? I understand that you say to withdraw the 6 degrees intake valve point but unclear why the intake valve/or is it lobe centerline would be at the 72 degrees BBDC location as apposed to the 78 BBDC position on the degree wheel?

Thanks