I am in the process of camming an otherwise stock 6.2 for a customer. I have found through many hours of research that merc used the ramjet cam in many of there 90s-2000s 6.2 motors so ordered one. So I searched online for a overlap calculator and found a very nice one here (no affiliation) and here (again - no affiliation) - the numbers add up on both.
https://mgispeedware.com/camshaft-calculator (this one is great cos you can enter 4 profiles and compare!)
http://wallaceracing.com/overlap-calc.php - Wallace Racing (very basic)
So I compared these two cams for my example:
- Ramjet cam (PN 14097395) - great cam option for the 6.2, tremendous torque, works on stock heads, great price and OEM made
- Comp XM270HR requires machining, springs, more expensive.
Please excuse my lack of expertise if I have missed anything critical or come across misleading but I really think some overlap numbers would really help us in cam selection options - would be wonderful if vizard could/would chime in on this
Here are my results:
Comp XM270HR: -3 degrees overlap
GM Ramjet cam: -19 degrees overlap