re: Scary noise when tightening cam cover nuts

["John Hertzman" <johnhertzman@domain.elided>]

There was a substantial thread on cam-cover cracks on the digest in November
1998 (probably similar a few other times too) and I was surprised this morning
that none of the several good people who responded today to Jon Pike's scary
noise hit any, let alone all, of the salient points discussed back then by an
illustrious group of sages (Simon Favre, Paul Rollins, Les Singh, Joel Hailey,
Lawrence Gowin, Steve Schaeffer, etc, and I won't name the well-known victim
who broke two camcovers to initiate that thread).

First, there are two different kinds of gaskets (not washers) used under the
cam-cover securing screws, aluminum (or aluminium) ones #105.02.01.582.00 that
go under the rear two fasteners, and the fiber ones #1306.12.028 which go
under the other four. Second, the semicircular rubber plugs at the rear of the
head are sufficiently oversize to maintain a good seal, and if either
installed incorrectly or old new stock which has age-hardened relative to what
it was thirty years ago they may stand proud of the mating surface, becoming a
fulcrum for the cam-cover which may bend until it cracks. Third, some people
casually applied the torque values for the cam-caps-to-head nuts to the
cam-cover securing screws. Fourth, some, accustomed to tightening head nuts,
wrongly tighten the center fasteners first. Fifth, click-type torque-wrenches
are often unreliable in the lower end of their range, and Real Pros have
theirs checked periodically by their Snap-On rep who has the checking
equipment.

So, the drill seems to be: buy an uncracked cover from APE; squish the
half-moon plugs down; fit the aluminum and fiber gaskets in the right places,
aluminum at the rear; run the fasteners down finger-tight and then ease them
all down progressively, starting at the rear (contrary to instinct born of
head-nut tightening sequences) to not more than five to seven foot-pounds.

If anybody knows better, please add; I am just summarizing old digest lore,
not speaking from other wisdom. Just looked in an old factory manual and a
couple of aftermarket ones and found nothing, which says something about the
value of our digest and the accumulated and shared knowledge of you good
people. Thanks -

John H.
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