Date:         Wed, 19 Mar 2003 09:03:45 -0800
Reply-To:     laurasdog@WEIRDSTUFFWEMAKE.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Steve Delanty <laurasdog@WEIRDSTUFFWEMAKE.COM>
Subject:      Re: cam breakin'
In-Reply-To:  <000301c2ee23$d278e6c0$4f0afea9@pacbell.net>
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<snip>

pensioner mumbles:

>Perhaps, perhaps not.  The camfaces are hardened, polished surfaces.  The
>followers are hardened polished surfaces.  The lubrication method is splash.
>There is no "sealing" needed as there is in the ring/liner interface.
>Nikasil liners and piston rings knead close tolerances to function
>effectively as a seal.  Cam-follower interfaces only need enough lubrication
>to prevent galling and micro-welding.

Steve pokes at the keyboard:

Well, I agree that cam faces are hardened, but they certainly aren't very
polished
until they've been in service awhile.
There's a tremendous amount of force on the cam and lifter faces, and with new
parts the surfaces are still not seated to each other so there's a lot of
friction
and heat buildup for a few minutes until these parts get used to each other and
the microscopic "high bits" are rubbed off.
As you mentioned, these parts are only splash lubed, so you need to make sure
the RPMs are up a bit to ensure that there's LOTS of oil to wash away the
gritty
stuff and provide plenty of cooling until things are broke in some and the
friction
and amount of wear debris is reduced.

That's my take on it at least...  I'm certainly not the expert, but I have
rebuilt
quite a lot of engines and installed a bundle of cams, and almost without fail
there's instructions with the cam describing how to properly break in the cam.
Almost always it is to be done around 2000 RPM, and usually large bold
print advises to NOT let the engine idle for the first 20 minutes.
I'm just following directions man...  (-:

Send a bit of email to one of the cam manufacturers and ask 'em what's
up with the 2K RPM break in...  let us know what they say.

Steve