| May/June 1982

44071 Clinton #A-4, Indio, California 92201

Early-day gas engines idling away at fairs and gas engine meetings are always an interesting sight. For those engines that are restored for display purposes where only a light work load or no work load at all is required, it if often an advantage to have the engine run slowly. This can often enhance the interest in the display and also make it easier to observe the mechanical operations of the engine. Although most early-day gas engines have some form of speed adjustment, certain minor modifications can be made to even further reduce the speed of the engine used mainly for display. This article will cover basic hints and modifications for hit-and-miss governed engines. These modifications are simple and do not affect the cosmetic appearance of the engine. Moreover, if it is ever determined to return the engine to its original working speed, the elimination of the modifications is equally simple.

Many of the governors on hit-and-miss gas engines have rather strong return springs on the governor weights to maintain the engine speed at something near 500 rpm. Replacing these original factory springs with lighter springs can substantially reduce the speed of the engine. It is relatively easy to replace these springs if the governor weights are mounted in an accessible location such as on a flywheel or on a camshaft gear. If the detent arm has a strong return spring, it may become necessary to replace this spring with a lighter spring or, in some instances, eliminate it completely. A strong spring forcing the detent arm away from the latched position may preclude slowing the engine even though there are lighter return springs on the governor weights. Many hardware stores carry an assortment of inexpensive light springs, making it possible for the engine restorer to find the right combination of springs to successfully reduce engine speed. Do-it-yourself spring winding kits are also available.

Once the engine speed has been reduced, the next step is to encourage the hit-and-miss engine to coast a little longer between firing cycles. When these engines were used for work and operating at their original RPM, the ignition was usually adjusted to fire at or slightly before top dead center. When the speed of the hit-and-miss engine has been substantially reduced, the engine will often run smoother and coast longer if the ignition fires at slightly past top dead center.

Some engines will have difficulty in drawing fuel up into the mixer or carburetor at lower speeds. This is usually because of the original style check valve at the bottom of the fuel line. These old style valves are often heavy and may even have a return spring forcing them in the closed position. This type of valve does not function easily at low speeds. One solution to this difficulty is to replace the original check valve with an extremely lightweight modern unit. (One example of a replacement valve is Briggs and Stratton part #296476, which can be used with ?' tubing.) These new valves function better than many of the heavier, older ones at lower speeds and will still work well if the engine is returned to its original speed. Some engines also have rather large fuel pipes leading to the mixer, and it is often advantageous to replace these with ?' tubing. This will also aid the mixer in drawing up fuel at lower speeds.

The suggestions mentioned here are both basic and relatively simple methods for reducing the speed of display engines. Undoubtedly, there are other methods to achieve the same end that other early-day engine advocates favor, and it would be interesting to hear about them.


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