[rexav8r]

First, I just got the car back from my mech and truely, it's never run better, since I've owned it !!

That said, I was a bit surprised at the sequence of events. My car (the '70E) has a rather fresh engine rebuild of approx 22K miles or so. I've done quite a bit of Auto-cross but I'm finally taking the plunge into DE this spring at Mid-Ohio, and I wanted the car to be mechanically fit.

I'm not that sure about the age of my MFI timing belt so I thought that along with an overall tune-up, since I had a new belt laying around I'd have it installed and the MFI timing reset along with the mixture which had gotten a bit rich.

I got a call from the shop the day after they started to let me know that my cams were pretty far out of time. In addition to setting the MFI timing they first would have to set the cam timing. Also a later (& larger) SC pulley had been installed along the way to facilitate cooling the engine. The car had been in Colorado for the previous 15 years with thin air. Unfortunately, the SC pulley is not indexed for a '70 motor.

Fortunately my shop had a "donor" 1970 S engine in back that they canned the correct pulley off of to reset the cam timing.

**Here's my question: What causes cams to come out of time? They can't really slip on the chains or can they. Is it simply a function of the valves losing their set position? Did the mech who did the previous cam setup screw it up ?