It appears that mine are the right color cores.
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http://i43.photobucket.com/albums/e3.../MK%20Cams.jpg

I have a cam here that has track marks on the lobe. It is an 8620 core. Now, this cam was mocked up in the block. Spun by hand with checker springs on two valves. I never noticed it until yesterday when I pulled it out of the box and looked at it. This cam wasn't spun (by hand) more than a dozen times when I was setting up the shaft rocker stands. How could this brand new cam have track marks on it? This is in a $4,000 block that was CNC machined to perfection with a $2,000 set of Jesel lifters and checker springs that I installed on the valves with my fingers= 0 spring pressure 0 rpm. What is gonna happen when I go and throw a big boy valve spring on and spin this thing 7,000 rpm?

On the inside or outside at SP?

The color on the cam cores is the copper plating. They plate the whole core. grind it, then harden. then regrind. Copper keeps the whole cam from hardening and breaking .

There is always going to be some marking , The cam is usually softer than the lifter wheel ( Jesel through hardens their wheels so the ID can be used as a bearing race for the needles) Now Jesel wheels are highly polished so on a less the optimum finish on the cam , it could be smoothing the finish on the cam. Like and english wheel on a body panel or a steel rolling mill. Be interesting to see the RA numbers on the lobe grinding. We always had our stuff REM finished.

after reading this post I am not feeling too good with my MK cams. I just got a heads and cams package specked from MK 2 months ago and numbers are not than much off of Tim's. thought I was doing the right thing going to MK spent to me was a lot of money building my 540's. my motors are almost finished and I may end up with a couple of 540 stones for the money I spent. that sucks. my grind # is XA242-390/247-385/112+4 core# 315629 actual on cam card reads 242.2 .664 247.1 .656 325 AFR heads

whats XA mean,,extra acceleration,,yikes and that 5° split sucks in a marine motor.I'd change that cam asap.

I like this cam for a sub 6000rpm 540. Very strong midrange and carry's the torque through the upper rpm so you can swing a decent sized wheel. Depending on exhaust peak hp should be between 5600 - 5800 with those heads.

http://www.lunatipower.com/Product.aspx?id=3153&gid=261

Perhaps another thread in the spring. Yours specs are very similar to ones out there running around all over and haven't necessarily had problems. I'd be questioning the hardening process and if he's still with CM etc. see if it's 8620 core. Also ask Bob if your gonna get more than 60 hours out of them?

You`d think after all these issues he`d go back to just copying stock grinds and changing them slightly.
Mistakes happen, trying new things isn`t a bad thing but realize the mistake, admit your mistakes, own it, make it right, learn from it, don`t repeat it, move on. That`s just good business.