Re: Pushrods

[jlandry@domain.elided (John A. Landry)]

In a brilliant stroke of genius, rikofwa@domain.elided (RIK D DESJARDIN) blurted
out:

>    Now knowing what I know about the lifters, that they must have been
>the primary cause of the noise.  Should I put it back together to see how
>it runs using the stock pushrods or the special order pushrods?

Rik,

It's my understanding that many hydraulic lifters... specifically IH
hydraulic lifters, are not supposed to be flat on the bottom.  They are
supposed to be ground very *slightly* tapered toward the center.  What you
have is basically a domed surface on the bottom lifter face.  The taper is
so slight, that it might not even be noticeable at first glance.  Laying a
straight edge on the lifter face will make the taper easily apparent.

Likewise, the faces of the cam lobes are supposed to be ground at a taper
across the entire surface.  What I mean is that one side of the lobe will
taper evenly across the face to the other side.

These two designs (the lifter and the cam lobe) work together so that the
lifter constantly turns as it operates.  The lifter face never is in
complete contact with the entire surface of the cam lobe... only a portion.
This uneven contact (caused by the grind) causes the lifter to rotate.

Could it be that the cam and lifters you purchased are not ground this way?
Could the lifter faces be perfectly flat along with the cam lobes?  If the
lifter didn't rotate like it should, then I could see a groove wearing into
the lifter face pretty quick.  All of the load would be concentrated on one
spot on the lifter face.

Couple the lack of a rotating lifter with heavier than normal valve spring
loading (due to a higher lift cam), and it's not surprising what your going
through.  I'd definitely check this angle out with some experts... maybe
the cam or lifter manufacturer or dealer.  I'm sure Delta Camshaft in
Tacoma, WA has the experience to offer some suggestions.  They can be
reached at 253-383-4152.

Just my thoughts.

Regards,

John
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