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Engine basics => Engine set up tips => Topic started by: Charles Hofacker on March 12, 2016, 12:09:31 PM
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I have two unrun Testors McCoy Series 21 engines: 1) .35 c/l and 2) .40 converted from r/c. I'm looking for the proper break in procedure. What "type" are they? ABC? or some thing else? I don't see a piston ring...
Thanks, CRH
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The McCoy 35 and 40 Series 21 engines had an aluminum piston with a single Dykes ring. I have the 35 R/C engine on a Kadet and it performs well. I don't think they need an extended breakin. Here's a link to Peter Chinn's review of the 40:
http://sceptreflight.net/Model%20Engine%20Tests/McCoy%2040%20Series%2021.html
Bob in NEPA
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Yeah, pretty much everything that Bob said. You don't see the ring because it's not where you think it is. A Dykes ring is right at the top of the piston and if the engines are new, it blends in. Break in is just a matter of putting enough fuel through it at an easy needle setting and minimal load until the exhaust comes out clean. Use all castor fuel or at least 1/2 castor and 25 to 29% total oil. Use a wood prop, 10-4 cut down to 9 inches or so. Run ir in a high four stroke setting, pinch the fuel line every now and then to clear it's throat. The exhaust will be black at first with metal, and will clear up quite a bit as the ring seats. It won't get crystal clear but I think you know what I mean and will see the difference from beginning to end. I've seen it in as few as 6 or 8 runs but may take more.
Good luck and have fun,
Dan McEntee
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These are excellent stunt engines. Though they look nothing like the old Red Heads, they run exactly like them but are much better made and longer lasting. I have quite a few of them from .19s thru .40s. I break them in just as Dan describes but do try to get about an hour of bench time. Do use at least 25% oil. If they are new when you get them use 50/50 castor/ synthetic. If it's already high mileage then use pure castor as that's likely what it was broken in and run with before. My new classic Skylark will sport a series 21 .40.
Dave