I can imagine after market cams ground wrong but not factory ones which all fail in time, My point is that to turn rotary motion to reciprocating we created two friction ramps, the old timers got it right with forged steel which dont wear. They then changed to nodular cast without introducing positive lubrication, the best hardening on cast is only .010" deep they all wear, ask Ford Chev Holden etc owners. Maybe drilling cam from either end with small holes in base circle and pressure fed by cam jounals would help. Now i have your attention Paul i am fitting Nissan exhaust valves ⎲mm] to my spare b20e head. The Nissan collets fit the Volvo caps perfectly, just cut to length and machine single groove using volvo springs at the preferred height. with porting it should make more power for road use without going radical with revs. Check them out if you have,nt already. The only way the contact point can be varied is to change the crowned radius on the lifter, i am sure you have explored this and make it work for you with a lot of dead cams along the way.