cam specs dont match when degreed

yellow rose said
Think about what you are asking. PRH already gave a good explanation of it, but consider the matter.

The intake and exhaust lobes NEVER change position relative to each other. Sooooo...if your cam is ground on a 110 Lobe Seperation Angle, that means that no matter what you do, the angle between the intake and exhaust lobe on any given cylinder must add up to 110.

Soooo...if you install your cam on a 106 Intake Center Line, the exhaust center line MUST BE 114 (106 plus 114 equals 220 divided in half equals 110).

If you move the Intake Center Line to say...100 then because the lobe position on the cam is fixed, the exhaust center line MUST be 120 because the sum of the intake and exhaust center lines MUST equal 110, which is the Lobe Seperation Angle.

So let's say you decide you want to install the cam with a 114 Intake Center line. Why you would do that, I can't say, but we are doing math so...why not.

If the Intake Center line is now 114, because the lobe position is fixed, the exhaust center line MUST BE 106, because the sum of the two must equal 110.

So think about this until you get your head around it.

Go to mgispeedware.com and put all your cam numbers into the program and then change your intake center line and see what happens.

You can see graphically what you do when you move the intake center line around.

PRH said
People often get hung up on the “advance” or “retard” thing, and how it relates to the numbers.

If you remember what the c/l numbers are referring to, it should keep you straight.
It can sometimes be easier to think of it in terms of direction.
You are moving the cam clockwise or counter-clockwise relative to the crank.
Whichever direction you move one lobe...... the other goes with it.

Look at the(typical) degree wheel....... if you moved the cam from an int c/l of 106...... clockwise 3*, the new c/l is 103.

If the ex c/l was 114 when the intake c/l 106, and you moved the cam 3* clockwise.......if you look on the exhaust side of the tdc mark of the wheel........what is 3* clockwise on the degree wheel from 114?(it’s 117).

Yellow rose and PRH, I went over what you said and checked the website YR mentioned. I went through some of my notes and took a look at the degreeing wheel and it all makes sense now. Thank you for the help to make things click. I went over everything and I managed to get everything degreed exactly at 106 CL on the intake. So thank you for your help understanding how everything worked together helped me do everything the proper way and now I feel confident in the work I did.

Wyrmrider said
did the grinder make the master or is it a copy?
If the grinder made a copy master does he have any idea about the design of the original?
or how he original was degreed?
If you had a after ground print you could see if the point was exactly in the center of the lobe- between the timing points
what was the original?

It's the master from the grinder and they checked everything for me so I was pretty sure it was an Error on my end, just wanted to get some insight from people that have been building engines for longer than I have been alive.