Yeah, I should have known better. The springs, it
turns out, were new (checked my receipts). So, the
only thing reused on the engine was the valves.
Rocker assembly is new. The cam isn't all that
radical, which was why we stuck with the old valves.
They do (and the other 5 still do) look new. Oh well,
false economy strikes again. And something happened
to trigger this. I was running on the edge before
that, I guess.
Gotta get me one of them Clarici "bang the pistons out
with a stump and run for years" engines next time.
--- cfchrist <cfchrist@earthlink.net> wrote:
> ron i cant remember if you said that you had used
> some nice used valves?
> if so i think you might encounter a problem there.
> reguardless of what they
> might look like they have an established wear
> pattern from old guides with a
> standard lift cam. with a difrent lift cam this
> puts the valve traveling
> further into the guide than it was previously. so
> at 1 piont you have the
> valve stem going down into the guide for it's first
> time at the top of each
> lobe. the rest of the travel is already the same as
> it would be on a stock
> cam with little exception.
>
> combining exhaust heat(expansion) with the
> posibility of close tolerances at
> guides ,exhaust valves live in a pretty severe
> climate. this could cause
> sticking and binding after it is warmed up. we
> often made exhaust guides a
> little looser than spec. called for. also took a
> die grinder and sheared
> off the protruding end of guide in the exhaust ports
> only! better flow,
> and less guide to worry about siezing on the valve
> stem.
>
> now stiffer valve springs relates to more pressure
> on the rocker shaft on
> the bottom side of shaft. excessive tolerance
> between shaft and rockers
> results in poor top end oiling. stock rockers are
> ok with a mild engine as
> long as they were ok to start with. care must be
> exercised when doing
> modification due to a trickle down effect. 1 thing
> was changed and 3
> things were changed from an established prior wear
> pattern to something
> diffrent. i hope that this might be of assistance
> with reguards to your
> problem.
>
> chuck
> still hunting for clue musk(he-he)
>
>
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