double or reversible
engine, however, is somewhat more difficult to handle in setting the
valve. Not that the valve itself is any different from a plain engine,
but from the fact that the link may confuse you, and while the link may
be in position to run the engine one way you may be endeavoring to set
the valve to run it the other way.

The proper way to proceed with this kind of an engine is to bring the
reverse lever to a position to run the engine forward, then proceed to
set your valve the same as on a plain engine. When you have it at the
proper place, tighten just enough to keep from slipping, then bring your
reverse lever to the reverse position and bring your engine to the
center. If it shows the same lead for the reverse motion you are then
ready to tighten your eccentrics securely, and they should be marked as
before.

You may imagine that you will have this to do often. Well don't be
scared about it. You may run an engine a long time, and never have to
set a valve. I have heard these windy engineers (you have seen them),
say that they had to go and set Mr. A's or Mr. B's valve, when the facts
were, if they did anything, it was simply to bring the eccentrics back
to their original position. They happened to know that most all engines
are plainly marked at the factory, and all there was to do was to bring
the eccentrics back to these marks and fasten them, and the valve was
set. The slipping of the eccentrics is about the only cause for a valve
working badly. You should therefore keep all grease and dirt away from
these marks; keep the set screws well tightened, and notice them
frequently to see that they do not slip. Should they slip a I/I6 part
of an inch, a well educated ear can detect it in the exhaust. Should
they slip a part of a turn as they will some times, the engine may stop
instantly, or it may cut a few peculiar circles for a minute or two, but
don't get excited, look to the eccentrics at once for the trouble.

Your engine may however act very queer some time, and you may find the
eccentrics in their proper place. Then you must go into the steam chest
for the trouble. The valves in different engines are fastened on valve
rod in different ways. Some are held in place by jam nuts; a nut may
have worked loose, causing lost motion on the valve. This will make
your engine work badly. Other engines hold their valve by a clamp and
pin. This pin may work out, and when it does, your engine wi