We are happy to have received another submission from Charles
Gray in the form of a continuation of an article he wrote last
year. In the July 2001 issue of Gas Engine Magazine, we presented
Charles’ article, Setting Up Your Oil Field Engine. The
article, intended for the novice oil field engine owner, offered
suggestions for gas and air settings that would make starting as
effortless as possible. It also included some information that
would be of interest to any oil field engine owner. Feedback from
readers was positive, making us feel the effort to provide this
information was worthwhile.
Two responses came from novice owners starting their engines for
the first time, and both of them stated they never thought starting
their engines could be so easy. We also heard from a fellow who
re-plumbed his hard-starting engine after reading that article,
expressing his surprise at how easily it now starts. This follow;
-up article answers a few questions that arose from Charles’
first article, and it also includes additional tips.
Air and Fuel Intake
The original article suggested that a gate valve be placed on
the air inlet to the engine to significantly reduce the inlet air
and provide a precise adjustment. Typical oil field engines have a
pipe-threaded 1-1/2-inch or 2-inch pipe at this location. If your
engine does not have a pipe thread you will have to improvise. Gate
valves can be purchased new at any plumbing supply house, or used
at flea markets and the like. You can also use pipe reducing
bushings and a smaller valve, if need be. The original article
suggested an initial opening of 1/8-inch as a starting point. We
now feel that a 1/16-inch opening is a better starting point.
The article also suggested that a valve with a diamond-shaped
opening or a needle valve be used to control gas flow. Gas valves
with a rectangular-shaped opening do not provide the precise
adjustment required, making starting difficult. Needle valves allow
better adjustment than diamond-shaped valves, and while the
diamond-shaped valves give a better appearance to the engine than
needle valves they are hard to find.
Small needle valves with 1/4-inch or 3/8-inch pipe threads
provide the best adjustment. A rectangular gas valve can be used
for the sake of appearance, with a small needle valve discreetly
located upstream for actual fuel control. Needle valves can often
be found at flea markets, and they can be purchased new from
various supply houses or one of the numerous suppliers advertising
here in GEM. They are available with the inlet and outlet in line
with each other or at a 90 degree offset.
Propane Tanks and OPDs
Any time your propane tanks are disconnected from your engine
you should make sure the safety plugs are reinstalled on the gas
outlet of the tanks. You should also install caps on the ends on
the propane hoses and cover the gas inlet on the engine. These caps
can be plastic plugs, metal caps or plain aluminum foil. The smell
of residual propane seems to attract spiders, and the spiders build
nests that block the flow of gas, making it difficult if not
impossible to start an engine later on.
Propane tanks must only be used in their originally intended
position. Do not transport, install or use a vertical tank in a
horizontal or upside down position. Propane is stored in the tanks
as a liquid and leaves the tank as a vapor. Using a vertical tank
in a horizontal position can allow liquid propane to enter your
fuel line, creating a hazardous condition.
As of April 1, 2002, portable propane tanks (40 pounds and
under) in the U.S. must have an Overfill Protection Device (OPD) to
be legally refilled. This is a requirement of the National Fire
Protection Association, and it means that any tank valves not made
to the new specifications are obsolete. The OPD valves have a
somewhat triangular-shaped handwheel on the shut-off with the
letters ‘OPD’ stamped on both the handwheel and the valve
body. They also have an internal flow-control device, which might
have the potential to cause problems with fuel flow. We don’t
know yet if this will be a problem, but you should be aware of this
if you are having trouble when trying to run off of one of the new
OPD-equipped propane tanks.
Running Speed
Depending on size, most oil field engines were originally
intended to run in the range of 140 rpm to 280 rpm, but most
collectors run them at around 100 rpm, or less. In order to produce
the smoothest running engine, as well as reduce shock on the
engine, it’s good to retard ignition timing when running this
slowly. With a Wico magneto spark ignition this can be accomplished
by adjusting the retard lever on the magneto.
Changing the timing on hot tube engines requires using either a
tube with a shorter internal length or a smaller inside diameter,
and this usually requires some experimentation with different hot
tubes. However, there is an easier way using your existing hot
tube, and that’s by simply dropping a short piece of loose
fitting steel pipe or tubing over the existing hot tube. Finding
the proper length will require some experimentation, but generally
it should be in the range of one to two inches. What this does is
to effectively move the hot spot up the hot tube, thereby retarding
the time of ignition. Keep in mind, however, that mild steel piping
used in hot-tube applications does not last long.
Pressure Regulators and Safety
The pressure regulators for propane fuel can be adjusted using
either a water manometer or a gauge that reads in
ounces-per-square-inch (not to be confused with gauges that read in
pounds-per-square-inch, or psi). The regulator for the hot tube
should be set at about 12 inches of water or seven
ounces-per-square-inch. The regulator for the engine fuel should be
in the range of seven to nine inches of water, or four to five
ounces-per-square-inch. These engine fuel pressures are valid only
if you are using a diamond valve or a needle valve.
The one thing that cannot be over emphasized is safety. Keep
spectators – especially children -at a safe distance from your
engine. If the engine is mounted on a trailer it is preferable to
have its mounting bolts go through the trailer frame, not just the
floor boards. If the engine sits on the ground, keep in mind the
ground may have soft spots. My preference is to bolt crossties
under the engine skids at the front and rear of the engine. They
must be removed when moving the engine, but they just about
eliminate any possibility of the engine tipping over while running.
Also, be careful when using any kind of unusual starting practices.
Those of you who follow the OFES on the Internet will recall the 10
HP Bessemer that upset while being started, destroying one flywheel
in the process. Remember, be careful out there.
This year the Oil Field Engine Society will have oil field
engines and equipment featured at the National Pike Steam, Gas and
Horse Association’s 22nd Annual Show in Brownsville, Pa., on
Aug. 9-11, and also at the White River Valley Antique
Association’s 18th Annual Show in Elnora, Ind., Sept. 6-8. As
with all OFES-sanctioned shows, these shows featuring oil field
engines have agreed to supply free camping for exhibitors and fuel
for their engines at the show. I encourage all OFES members to
support these shows.
As always, if you like a free membership in the OFES, please
contact me at the address below, or visit us on the Web at: www.
oilfieldengine. com
Contact the Oil Field Engine Society at: 1231 Banta’s
Creek Road, Eaton, OH 45320-9701, or e-mail at:
oilengine@voyager.net
‘Keep in mind/ however/ that mild steel piping used
in hot-tube applications does not last long.’
