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Engine basics => Engine set up tips => Topic started by: Russell Shaffer on June 29, 2006, 07:54:18 AM
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I have a Fox Rocket 35 from about 1962 that I am installing on a profile. I bench ran it and it does shake some. Has anyone tried using a rubber layer in the doublers to try and tame some of this? Any other ideas? Thanks
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Russell.
Very much doubt that a rubber layer built-in in the doublers would do a single thing. It sounds like a lot of effort for little likely return.
Some Fox engines softened up their vibration as they got time on them (slant plug 1970's 29 and 36, for example), or we just got used to them shaking...
Strong front end on the model would help...
Make blessed sure the prop is VERY well balanced.
Possibly adding a head gasket, or even two, might soften the combustion.
Don't run the engine "hard" - find a setting that is near, but not at, totally peaked out - or if you're looking for a smooth 4-cycle to get a 4-2 break, I don't know if this engine is timed/ported to make that easy.
Use a somewhat lighter prop load - say 9-6 or 10-5 instead of a 10-6. It may be happier in easy-wet-low 2-cycle all the way with a flatter pitch prop, even a 10- or 10.5-4.
If fuel has any effect, a 10%nitro, (at least) 25% CASTOR oil fuel may be kindest.
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Won't get any 4-2 breaks out of this thing. It is kind of a poor man's combat engine. Pretty strong, but smooth isn't in the description. I'll let you know what the rubber does, good or bad. It wasn't very hard to put it in, and if things are worse, I'll replace rubber with ply. Thanks
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I've flown it now, that was a big event, by the way. It's been a long time. The engine ran fine and didn't seem as rough as on my bench setup. Guess I'll have to remove the rubber layers and try it again so I have something to compare with.