Me and a friend have also had issues with cams. Between us we have gone throught 5 cams including ford and kent. In the end im running a motorfactors copy for £100 with no problem and my friend is running a power engineering cam with doulble springs. No problems so far in the last 4000 miles.

I belive that the tappets are the weak link. The kent ones were braking up and some of the brand new motorfactor tappets were not turning.