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Issue link: http://gcmdigital.gcsaa.org/i/302556
34 GOLF COURSE MANAGEMENT 05.14 Last month's column covered two of the seven major factors involved in fnding a proper new-era small engine to replace a worn out old-technology engine: chassis impact and power rating. Once you've decided what power to get in a replacement small engine, there are sev - eral physical dimension issues that have to be resolved. Envelope. Start by measuring your old en - gine. Save time and headaches by using a met- ric ruler. A typical new engine dimension "envelope" is published as length × width × height; for example, 12.481 inches (317 mm) × 16.4174 inches (417 mm) × 15.9845 inches (406 mm). Unless your brain has superior mathemat - ical powers, stick with metrics. Be sure to add some extra air space around the envelope for clearance and access to service points. Remove the shroud to expose the center of the crankshaft — this is the starting point for the most critical "envelope" dimensions. Get an idea of what dimensions you'll need by vis - iting www.smallenginesuppliers.com . You'll fnd oodles of engine drawings for seven dif - ferent engine brands. While dimensions are often a chal - lenge with horizontal-crank one-cylin- der engines, there's usually less hassle with vertical-crank engines. The new verticals are usually a little longer from crank center to top — the OHV pieces naturally make the cylinder head taller. Since machine designers left room to get at the fathead's top-mounted spark plug, there's usually room to spare. You'll fnd that verticals offer some variety in the placement of the exhaust and intake sys - tems, making it much easier to fnd a replace- ment. Rerouting of control cables is often the only vertical-shaft challenge. Cranks aft matc . The crankshaft length, diameter and shape is the dimension that poses the greatest challenge. When you're lucky, the crank is just a "standard" round shaft with a keyway. The diameter starts at 5 / 8 inch for the smallest engines, then rises to 1 inch. You can usually fnd adapters to increase crank diam - eter on eBay or from a large industrial or elec- tric-motor supply house. Our failing 5-hp Briggs has a 1-inch crank, thicker than the (shop) Scott R. Nesbitt ORPguy@windstream.net standard ¾-inch for that size of engine. We found the adapter we needed. It came with a "stepped" key that would ft the 3 ⁄16-inch crankshaft keyway as well as the ¼ inch re - quired by the rotor on our chipper-shredder. Also shown is a ½-to-1-inch adapter for an - other project. If your crank is not standard and/ or straight, start with the parts list for your specifc model of engine. Use the type num - ber to fnd the crankshaft part number. Use your local small-engine merchant or the www.smallenginesuppliers.com site to locate your engine's crankshaft drawings. Chances are the crankshaft itself will be obso - lete. But if there's joy in the world, you can fnd a new engine with a crank that matches ex - actly. You have very little wiggle room, espe- cially for tapered crankshafts used in electri- cal generators. Mounting mat Once you have located a candidate with the right crankshaft, zoom back to your dimension drawings and verify that it has the proper mounting points — through-holes in the base or tapped mount - ing holes in the crank-face of the engine. Our replacement engine had only four holes in each location, and they match the old pattern. Many replacement engines will have 8, 10 or 12 bolt patterns in the crank-face. There are often more holes on the sides to mount electric starters and other accessories. Service access and repair parts. The engine in the photo has oil drain and fll on two sides, came with a long-tube wrench to get at the spark plug and has a simple sponge air flter. Routine service should be easy. But parts are an open question. The maker is Chongquing Rato Power Manufactur - ing Corp. of China. The engine cost less than $110, including freight. The crank adapter cost $20. Can that engine really do the job? What if it needs a carburetor kit? At the end of this series, we'll report on our experience. Until then, we'll take a look at why and how small engines have changed so much in the last decade. Scott R. Nesbitt is a freelance writer and former GCSAA staff member. He lives in Cleveland, Ga. Replacing orphan engines: Part II Top: Measure your old and new engines with a metric ruler and save the headaches of converting inch measurements into decimals and back to fractions. Bottom: An adapter increasing the crank- shaft diameter to 1 inch requires a specially machined "step" key with two dimensions. Photos by Scott Nesbitt 034-035_May14_Shop.indd 34 4/16/14 2:44 PM