NC30 - cam degreeing logic

[lukemillar]

Hey

I'm in the middle of installing some new camshafts (not a stock profile) and I wondering if anyone can confirm my gear-driven cam logic.

There are 40 teeth on an NC30 camshaft. So 360 degrees / 40 teeth = 9 degrees per tooth

Therefore, slipping a camshaft 1 tooth will result in an advance or retard of 9 degrees? Been scratching my head for hours on this as that is not what the numbers are telling me. I think it is to do with to profile of the cam being asymmetric (which I'm waiting to have confirmed), but would also be great if someone can tell me the maths is sound and I'm not being thick!

Cheers
Luke

[jetblack]

Surely 9 degrees is way too much? Don't you need adjustable cam gears so you can dial in 1 or 2 degrees?

[krisztian_andre]

I can definitely confirm that 360 / 40 is in fact 9

[lukemillar]

Surely 9 degrees is way too much? Don't you need adjustable cam gears so you can dial in 1 or 2 degrees?

Yes and no. I'm just trying to install these cams straight up, but need to confirm that I can't do that in their current state, so I'll need to get them slotted.

[999Gomerz]

It may not be 9 degrees. It would depend how many times the camshaft turns in relation to the crank. If the cam turns twicè for every 1crank turn then it wold be 4.5 degrees per tooth.

[lukemillar]

It's the other way round - the camshaft turns once for every 2 crank rotations.

I think I have found the issue- It is an asymmetric profile; I just need to alter where I am taking my measurements from.

[999Gomerz]

It's the other way round - the camshaft turns once for every 2 crank rotations.

I think I have found the issue- It is an asymmetric profile; I just need to alter where I am taking my measurements from.

Are you measuring at 1mm lift?

[lukemillar]

It's the other way round - the camshaft turns once for every 2 crank rotations.

I think I have found the issue- It is an asymmetric profile; I just need to alter where I am taking my measurements from.

Are you measuring at 1mm lift?

No, I was initially measuring 1mm either side of max lift to get the centreline. The lobe profile initial opening/closing is where I switched to e.g 1mm lift. However, with the cam holders being the way they are, getting a dial indicator in there is a real PITA! Anyway, I'm sorted now, I finally got some accurate and consistent numbers, which just confirmed what I suspected in the first place, which is I need to slot the cams.