Most engine people have had an engine with
rusted, damaged or missing valves that needed replacement. A
slow-running show engine can get by with a lot of problems, but
when a part is missing or unrepairable, the engine is shut down. If
you are lucky and have a common engine you can order a new valve,
but the price will be $20 to $35 each. If you have something rare,
the price is “contact us for details.” You can bet it’ll be over
$35. But there is another way to replace valves for engines of this
type.
Finding Valves
At the next swap meet you go to, just look in the junk parts
boxes. You should be able to get a handful of old, unidentified
valves for a quarter apiece or so. I look for valves with stems
around 3/8-inch, which is a good size for most of these
engines.
Photo 1 shows an original Nelson Bros. valve with a burnt spot
at the arrow. The other valves came from unknown engines. The one
on the left has a stem that is too small. The one on the right is
too large. The last one, as Goldilocks said, is just right.
“Just right” means the stem is the same diameter as the
original. The head is too large and the stem is too long but those
problems can be fixed. If you use the original valve as a pattern
and trace the size of the new valve with a Sharpie as shown in
Photo 2, you’ll see how much material has to be taken off.
Photo 3 shows the valve chucked up in an electric drill and
being ground down on a grinding wheel. A lathe is not needed, as
exact precision is not necessary. Just grind until the entire
Sharpie mark is gone and you will have the correct diameter as
Photo 4 shows. Of course the rim is too thick and there isn’t
enough face area. Just hold the drill at a 45-degree angle and
grind off enough for a proper face angle. It is better to use a
fine wheel than the coarse one I used, but it worked.
The stem is still too long and is hardened. Mark the proper
length and heat that spot red hot as in Photo 5. Cool slowly to
anneal. Now it can be cut with a hacksaw. Drill a 1/8-inch hole in
the tip for the cotter pin and your valve is finished.
A normal valve job with plenty of grinding compound will lap
everything in and you will have good compression for a good-running
engine – without spending the price of a dinner out for your whole
family (Photo 6).
If your engine’s valves are totally missing, you can determine
the proper stem size by slipping bolts of differing sizes in the
valve guides. Head diameter would be very slightly larger than the
diameter of the valve seat in the head. Stem length would be just
long enough to allow for a spring and keeper. Looking at other,
similar engines could indicate how far a valve should stick
out.
The last photo shows the Nelson Bros. Sattley head with old
repairs. Note the valve guide was brazed back on and the rocker arm
stud was broken off; it has a homemade valve and it still runs. If
you mess it up, just try again. It only costs pennies and a few
minutes of your time.
Contact engine enthusiast John Hamilton at: 910 W.
Marvin Ave., Waxahachie, Texas 75165;
a.p.hamilton@worldnet.att.net
