Todd W. Sigety wrote:
>
> Jeff,
>
> Could it it be a bent push rod? Happened to my TR6.
>
> Todd Sigety
> 1970 TR6
> Alexandria, VA
>
> Jeff Johnson wrote:
> >
> > I'm stumped. My TR began to run badly as if it had a valve problem, so I
> > decided to check the valve lash yesterday. ( I thought maybe I had
> > broken a valve spring ) In running through the sequence, I noticed that
> > the # 8 valve did not travel as far as the others. The adjuster
> > appeared to be set the same as the others. After setting the valves, I
> > started the engine and watched the pathetic action of the #8 valve and
> > attempted to adjust it while running, but it killed the engine. Could I
> > have a bad lifter or a bad lobe on the cam? Anyone have an opinion as
> > to the problem?
> >
> > I'm not wild about yanking the head as it will probably be 2 months or
> > longer before I'll have the time and garage space to get into it.
I doubt it would be a bent pushrod unless you saw large amounts of
clearance at that valve before beginning the adjustment. Just the way
the geometry is.... But--checking that is simple--just compare #8
pushrod against other lengths.
Unfortunately, providing you saw no large clearance at that valve, it's
very likely that the lobe (and likely the lifter, as well) are worn. If
static clearance is normal when the lobe is down, that's the point of
least resistance, so there would be little wear on that point of the
lobe to change the cold clearance. And yet, if the lobe is worn, there
will be less lift.
You don't need to pull the head to determine this--simply make careful
measurements at either the heel of the rocker arm, or at the valve
spring retainer, for several of the same valve (#8 is cyl. 4 exhaust),
so check other exhaust valves against #8. Just remember to take
consistent measurements in the same place on each. Also remember that
the measurement will be different at the heel and the toe of the rocker
because of the rocker ratio.
One other possibility for this is a badly worn rocker or rocker
shaft--but you could likely see and hear excessive movement were this
the case. Worth checking, at any rate.
Cheers, Jeff.
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