stunthanger.com
Engine basics => Engine set up tips => Topic started by: Harold Brewer on July 25, 2017, 10:16:57 AM
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I have been trying to break in a Fox 35, and have been having flooding problems. I am using the very last
Fox needle assembly (the one that has the fuel delivery coming into the needle valve at an angle). I also
noticed tha the venturi seems large. I started looking at my stash and found two that had venturi inserts. Were Fox 35's supplied with venturi inserts, or are the ones that I have, custom made (engines bought used).
Brew H^^
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No venturi inserts that I ever saw. Just a very small die cast hole.
If you want to try & see what happens when you go smaller, you could half the hole with a carved wood wedge. I think you will find that the power reduction is not as much was you expected.
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You may have a Fox Combat special or similar higher performance engine. I have never heard of an insert on a Fox.35 stunt engine. There is on the early .36 CS engines I believe. I have stuffed a stick into a venturi on occasion to get some extra fuel mileage out of a model with a too small tank. Maybe a picture would help us?
Type at you later,
Dan McEntee
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I have Fox .36x that has an insert, but its square.
Steve
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Harold,
The Fox 35 does not have any inserts. If your are having flooding problems you may have the tank mounted too high on test stand. If you are using a plastic tank it is usually ticker (1 1/4") than a standard 1" tin tank. For a test stand, set the tank so the center is say a 1/4" below the spraybar. Also don't try to run it too rich. For break-in you could use a 9x5 prop (to keep the load and heat under control), with 5% nitro, 25% oil fuel (could use 50/50 syn/castor or straight castor).
Best, DennisT