Setting Up Oil Field Engines
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.
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.
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.
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.
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: email@example.com
'Keep in mind/ however/ that mild steel piping used in hot-tube applications does not last long.'