Fox Carburetor Adapter for ASP .61 engines - RC Groups
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This thread is privately moderated by earlwb, who may elect to delete unwanted replies.
Jul 06, 2012, 09:21 PM
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earlwb's Avatar

Fox Carburetor Adapter for ASP .61 engines

One of our forum members "Gary Cee" was kind enough to make me a couple of Fox carburetor adapters for some other brand engines. I think he did a really excellent job as the adapter fit perfectly too. Thank you very much Gary Cee, I really appreciate it a lot too. This allows me to use the really good Fox carb on a engine that doesn't quite have as good of a carburetor on it. In this example it is a adapter for a ASP .61 engine. The OEM carb on the engine actually works OK, but the bore is too large. Thus you have to let the engine turn higher RPMs (smaller props) and use a more restrictive muffler, that provides extra back pressure for the fuel tank, in order to get good fuel draw out of the engine. Quite a few people ran afoul of the problem of a carb bore being a little too large for the engine when they used a Pitts muffler that had a lot less muffler back pressure for the pressurizing the fuel tank. They usually had to block off one of the exhaust outlets to increase the muffler pressure for the fuel tank, but even then it may have been somewhat marginal. But by using a carburetor with a little smaller bore to it, I can get good fuel draw for the engine, and it is much less sensitive to fuel tank location and also to needing extra muffler pressure. So I have more versatility and better all around performance with the engine. Besides the Fox carburetors are really good carburetors and well worth using on engines other than Fox engines too. The cost for a Fox carburetor isn't all that bad and quite attractive cost-wise when you compare the cost to some of the other brand name carbs as well. The flange design of the carb does work really well, in that it prevents warps from causing the carb to bind when you attach the carb using clamps or screws. But the flange makes it more difficult to adapt the carb to other brand engines though.

Comparing the larger bore of the ASP carb to the smaller bore of the Fox carb.
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Jul 07, 2012, 11:45 AM
Grumpa Tom
Kmot's Avatar
Very nice upgrade!
Jul 15, 2012, 10:25 AM
Registered User
earlwb's Avatar
Thanks, I have been messing around with some other things, so I haven't gotten around to running the engine yet. But I think it will be a nice improvement.

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