<VV> "Checking" for cam and lifter wear

[Mark Durham]

Using a dial indicator is the easiest and least invasive method to
measure lobe wear, however, if you have lifters that leak down, you
may not get a good reading.

My engine had three cam lobes go bad before the engine suffered a
performance loss I noticed. There are too other ways to check lobe
wear. Pull the top and look with a good flashlight and mirror. Worn
lobes are flattter and wider across the top, have jagged edges that
will slice open your finger, and will be pitted.
Second, pull the lower shrouds, valve covers, rockers and push rods,
then the tubes. Remove each lifter one at a time and look at the
bottom. A nice wear in pattern should be evident. Corrosion and or a
line across the face means the lifter has stopped turning, the lobe is
worn, and disaster is imminent.
Do not mix the lifters up. Each lifter/cam lobe mates to each other in
a pattern unique to them.

If the wear is normal looking on all lifters, put the engine back
together and keep running the engine. Like apples in a barrel, it only
takes 1 to spoil things.

 Mark Durham

On Sun, Feb 27, 2011 at 6:10 AM,  <djtcz at comcast.net> wrote:
> Original message
> From: "Ray Rodriguez III" < vairguy at echoes.net >
> Subject: Re: <VV> a different oil conversation
> ........................
> Is there any easy way to check an engine to see if it has already sustained
> significant wear of the cam lobes without taking the engine apart beyond
> valve covers and oil pan removal? ..................
>
> The conclusion I draw from this is that the ZDDP is probably a lot more
> important to engines built with new parts, particularly hi-po custom builds.
> Those with stock engines and original GM cams are far less likely to ever
> have a problem and might not concern themselves with the ZDDP issue.
> ------------------------------
>
> Jeg's and others have 1 inch travel dial indicators and mag bases for fairly short money.
> Mag bases are not useful on aluminum blox-n-heads, so a hunk or bar of something ferrous must be afixed to the engine first.
>
>
>
> Position the indicator parallel to the valve stem, and contacting a flat surface on the retainer. The measurement will be net valve lift ( cam lift X actual rocker ratio (-) who-knows-what for a little lifter leakdown)
> I'd probably rotate the engine thru many revolutions looking for repeatability even though only 2 revs are required to capture a full lift event.
>
>
> I am not at all confident a well seasoned low performance OEM cam in good running condition will never, ever need a splash of ZDDP, etc, when the oil temp is a little high and the viscosity at the rubbing surface happens to be just a little too thin, or the oil splishes instead of splashes and the quantity delivered is a little low, or slightly misplaced. Some of the lifters share lobes, so on one bank the lifter/cam interfaces only gets oil that is still clinging to the cam lobe after it has already run close by or even through the other bank's valve opening event.
>
>
>
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