flat tappet cam in magnum motor?

Bill Dedman said
But, the ones that failed had been in the cars for a couple of years, so were apparently broken in properly, since they'd had no problems up to that time.

Of course, they're not MOPARS, but the principle is the same; the ZDDP provides the high film-strength barrier that the lifter/cam interface needs for longivity.

G.M. quit selling that "Engine Oil Supplement" a while back, but according to "Pit Stop" in the latest HOT ROD, it's back, although now, with a different part number. Go figure...

I have no personal experience with cam failures, so all I can do is report what I've seen happen to these Buicks.... You can believe what you want, but based on their experience, I'd say that ZDDP is needed by any flat-tappet cam, for longivity.

Just my 2-cents.... and worth every bit of that (two cents... LOL!)

Bill, in Conway, Arkansas

I totally agree. ZDDP is needed for the life of the engine. Not just during break-in because the that cam and lifters are allways scrapeing together with much more friction than any other part of the engine.

An example is a buddy of mine put a comp XE268 in his 454 Chevy 2 yrs. ago. It ran fine for allmost 2 yrs. had over 7,000 miles put on it and recently it started loosing power and then lifters started clacking. He pulled the cam/lifters and 4 lobes were nearly flat. We can find no other reason that this happened other than he used oil with no zinc additive after the break-in period in which he did run ZDDP additive. BTW: The spring pressures were 105 seat and 280 open. Not much pressure there.