RE: Should I change cam followers?

[Hirsch <Catenary@domain.elided>]

Graham Hilder asked about a discussion on the Digest on
installing new cam followers. I remember this discussion
as I was part of it. Below is a summary of what was said.
(From Jan. '98, AD v. 5, 353 & 354.)

R Hirsch said:

>> The Crane Cams website at www.cranecams.com includes a FAQ on
camshafts. Here's an excerpt:

Q: Must New (Standard Design) Lifters Always be Installed on
a New Camshaft?

A: YES!! all standard hydraulic and mechanical new camshafts
must have new lifters installed. The face of these lifters
have a slight crown, and the mating lobe surface they ride
on has been ground with a slight taper. The purpose of this
is to create a "spinning" of the lifter as it rides on the
lobe. This is necessary to prevent the lifter and lobe from
premature wear. Therefore these parts will be mated to one
another during the initial break-in period. Used lifters
will not mate properly, causing the lobe to fail. <<

To which Tom Sahines responded:

>> In a recent post there was a reference to the changing
lifters when installing a cam and how the lifters had a
crown which cause them to rotate. The Alfa engine design
uses an overhead cam and a direct acting lifter. This is
the cup that rides in the bore of the head and pushes on
the adjuster pad which in turn pushes on the valve. The
Alfa lifter has been designed to be flat on top (no crown)
and does not turn like some other engines. When a valve job
or cam replacement is done it is imperitive that the cups be
checked for flatness. I do this by sanding them lightly. Place
a piece of 240 wet/dry sandpaper sprayed with WD-40 on a sheet
of glass (the glass is a very good flat surface). Then sand the
top of the cup by holding it against the sand paper using a
figure 8 pattern so that the sanding lines do not go all the
same way. If the cup is good you will see an even sanding mark
pattern across the top of the cup. If the cup is bad there will
be areas where there are no sanding marks. The bad cup should be
replaced with a new one or a good used cup. If the distortion is
minimal a good machine shop can surface grind the cup as well.

I have found that used cups that are flat or reground cups will
perform well with new cams and GOOD used cams. There is another
group of cams which are sold as reground cams. Some of these cams
have been welded to increse the material on the lobes so that when
they are ground the clearance between the cam and valve will remain
as stock otherwise you have to use very thick adjusting pads. For
these cams I always use new cups. Using old cups will result in
premature wear on the cam lobes.<<

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