I have to jump in here because just yesterday afternoon I was adjusting the
valve lash after torquing down the engine.
Being inexperienced in mechanics, I followed the Haines in torquing down the
engine hot and then, adjusting the valves on a cool engine to
specifications.
To my surprise, the next thing I hear is that this could have maybe done on
a hot engine with maybe better accuracy. Somewhat surprised, I was now
questioning the specification for this procedure, but since nobody seemed to
know, I opted to stay with the known facts and play it safe. No sense in
playing around with unknowns and risking burning out a cylinder.
Let common sense prevail.
My 2 cents.
Liv
----- Original Message -----
From: "Michael D. Porter" <mporter@zianet.com>
To: "Bill Miller" <millerb@ivwnet.com>
Cc: <spitfires@autox.team.net>
Sent: Thursday, August 22, 2002 9:44 PM
Subject: Re: tappets
> Bill Miller wrote:
> >
> > I also set them while running. It is very easy, I never have once got
> > burnt. If you have ever had the valve cover off while the engine is
> > running, you will see that the spitfire engine does not spray oil, it
more
> > or less dribbles it up there.
> >
> > IMHO, running is the only way to correctly set the gap. You will never
get
> > the exact place on the lobe by rocking the car, in gear to get to the
"high"
> > spot. But you will running.
>
> Okay, Bill, what's the hot lash specification and for what engine? That
> was the original point. The guy asking didn't know if the published lash
> was hot or cold. It was that simple.
>
> Sorry, but this persistence in recommending checking the lash hot is
> going to ruin some engines, unless you and others are willing to specify
> the correct hot lash for the engine(s) in question. You and others are
> contributing to confusion unless you give a hot lash spec.
>
> I apologize if I seem to be insistent on this, but not a single poster
> recommending setting lash while hot has provided a spec for doing so,
> for any engine. If the cold spec is used when the engine is hot, the
> valve train is going to be damaged. Period. Without specific hot valve
> lash specifications, I consider recommendations to do so to be dangerous
> and ill-advised--and a disservice to the uninitiated on this list.
>
> Let me give an example. Twenty-five or so years ago, I spent a lot of my
> time rebuilding VW air-cooled engines, but wondered why the valve lash,
> cold, was only 0.006". So, I set the lash correctly, cold, then ran an
> engine up to operating temperature and checked the lash hot. It was
> 0.015" on the intakes and 0.016" on the exhausts. After a couple of
> tests, I could be fairly certain that those figures were correct when
> hot. However, if I had set both the intakes and the exhausts to 0.006"
> when hot, in the belief that setting valves to that spec, when hot, was
> best, I would have burned up every engine I built.
>
> My earlier point was that the suggestion to set valves hot was useless
> without a hot spec. That hot spec is _different_ than the cold spec, and
> further, if the cold spec is published, the ordinary user should set the
> valve lash when the engine is cold. Period. No argument, no niggling
> about details, or arguments about the "best way" without the data to
> support that view.
>
> There are a lot of people on this list who are not experienced mechanics
> and desire simple, straightforward advice about how to maintain their
> cars. In this case, simply how to set valve lash. This is an
> extraordinarily simple issue. Don't complicate it without providing
> _all_ the necessary correct information. If you recommend adjusting the
> lash hot, provide the correct specification. If you don't have that
> spec, just cease and desist. Other people's are at stake.
>
> Cheers.
>
> --
> Michael D. Porter
> Roswell, NM (yes, _that_ Roswell)
> [mailto:mporter@zianet.com]
>
> The gulf between content and substance continues to widen....
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