Re: Cam checking, Landry, etc.

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

As the little green aliens inserted a searing hot probe into the sternum of
Doug Rasmussen <DougRasmussen@domain.elided>, a blood curdling scream was
heard...

>Ok, John L.  You're going to check your new factory-style cam to make sure
>it meets specs.  Now I'm curious.  Exactly how are you going to do this
>checking?
>
>Put the cam in the block, rig up some kind of solid tappet-sized rod and
>measure lift with a dial indicator as you rotate to the appropriate degree?
>  And repeat for each of the sixteen lobes?  That's the easiest way I can
>think to do it.

That's pretty close Doug.  You do install the cam and crank in the block along
with the timing gears.  You fasten a "degree wheel" to the front of the crank
and you make a wire pointer for it which is secured to the block next to the
crank.  A minimum 1" travel dial indicator is used along with a magnetic base
to measure the travel of the lifters directly, or via a lifter modified with a
pushrod in place in the block against the cam.

Degreeing the cam is not terribly difficult, just tedious enough so it's sort
of a pain and probably avoided by most rebuilders.  As I understand it, if
they check a cam at all, many people just check one cylinder and call it good
if that's in spec.  Anal folks like me will want to check all the cylinders of
course.  <grin>

The biggest hassle about it is that you have to find *exact* top dead center
for each cylinder being checked.  No eye balling is allowed.  You either have
to use a device called a piston stop in conjunction with the degree wheel or
use a more involved technique which involves reading the dial indicator and
averaging out errors on the degree wheel until they are eliminated and TDC is
found exactly.  Once TDC is found, then the rest of the procedure is just
reading the degree wheel at a certain lifter height (movement) and recording
the results.

Complete detailed procedures are covered in many engine building and hot rod
type books.

Take care,

John L.
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