flat tappet cam in magnum motor?

Every Saturday morning, I go to breakfast with a group of Buick turbo guys, all of whom have 1986-'87, 3.8-liter Grand Nationals or T-Type Regals ("Grand Nationals" that are not black.)

Those cars came with flat-tappet, hydraulic cams. They also have notoriously bad engineering on their rocker shaft hold-downs, utilizing only four 5/16" bolts (they MAY even be quarter-inch; I'm not sure, but they're way too small for the job, in any case) to anchor the rocker shafts to the heads. That, alone, keeps them from running much valve spring pressure; but the weak crankshafts in those cars also keeps them from turning over 6,000 rpm, if they want reliability at all...

So, these engines have minimal valve spring pressure, and operate below 6,000 rpm.

Of the 9 or 10 guys who come to that breakfast, at least six of them have wiped out cam lobes since the government took zinc out of the oil. Several of them have changed over to roller tappet cams, and the others have installed new cams, and use G.M. Engine Oil Supplement (heavy ZDDP content) continuously, to try to not ruin another cam.

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