Chimaera cam wear

[Tonychimaera]

Hi, please see the attached photo of my standard cam on a 38000mile Chimaera, not sure whether looks ok or not, any advise welcome. Cheers

[Sir Paolo]

The rotary action of the lifters does create a wear pattern that looks like there isn’t even wear across the cam lobes.

There should be a more evidence of contact on the tips of the lobes, than the heel of the cam.

It’s difficult to see from the photo, but I don’t think you’ve anything to worry about.

It would be worth checking the lifters spin in the bores.

[Steve_D]

Of the 3 lobes in your view centre and right hand are showing the back of the lobe which does no work so often looks a bit strange. (Imagine an egg with a rounded end and a pointy end. The pointy end of your cam is the bit doing the work the rounded end does nothing).

You need to be looking at the pointy bit. Keep turning the engine over by hand to look at the point of each lobe. (try and look directly along the engine so you can see the lobe side on). You will find plenty that have a really well defined point. Keep this image in your mind as you continue to look at them all. I'm betting you will find at least 3 that you can clearly see are not as good as the others. You may even find one or more that are difficult to tell which is the pointy bit and which the roundy bit.

The technical bit is that a camshaft is relatively soft which allows it to resist twisting etc. After it is machined it is 'Case Hardened' which only hardens a thin layer at the surface. This hardness resists wear.
What then happens is wear takes place over time but as soon as the wear goes through the case hardening further wear takes place quite quickly.
This is why most of your cam will look good but the worn lobes look really bad.

Steve

[Tonychimaera]

Thanks very much for that, I’ll have a real good look.

[rev-erend]

Some nice pictures of wear here

http://www.v8wizard.com/Camshaft_wear.php

http://www.v8wizard.com/How_to_identify_worn_cams_...