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Engine basics => Engine set up tips => Topic started by: scott v. on October 12, 2016, 03:28:22 PM

Title: fox 25 with bolt on venturi
Post by: scott v. on October 12, 2016, 03:28:22 PM

What prop do you use for flite streak with a Fox .25

Thanks, Scott

Title: Re: fox 25 with bolt on venturi
Post by: dennis lipsett on October 12, 2016, 04:29:44 PM

Quote from: scott v. on October 12, 2016, 03:28:22 PM

What prop do you use for flite streak with a Fox .25

Thanks, Scott

9-5 works well

Dennis

Title: Re: fox 25 with bolt on venturi
Post by: scott v. on October 13, 2016, 01:06:13 PM

Do you have any idea of what takeoff revs you have?  I was running a 9-6 and probably leaned out more than it should be - lap times were way too fast.  This motor is much more than the worn out McCoy .29 I had on it.

Title: Re: fox 25 with bolt on venturi
Post by: Steve Helmick on October 13, 2016, 05:25:32 PM

Be sure to run fuel with a good dose (22-25%) of oil, at least half that being castor.

I'd try a 9-4 APC, 10-4 APC, 9.5 x 4.5 APC, and a 10-4 Xoar, and see which works best. These are not 4-2-4 engines, but should run a decent "2-2-2" or "rich 2" run. Might need a few layers of nylon stocking material over the venturi to effectively choke down the venturi size. A bigger spraybar probably wouldn't hurt, either. 

The (hollow) nose of an ARF Flite Streak might fail due to the typical Fox vibrations, so be careful with that.  D>K Steve

Title: Re: fox 25 with bolt on venturi
Post by: M Spencer on October 13, 2016, 08:32:31 PM

Theres in fact TWo versions of the 25 , one from the 80s , maybe with the black prop driver , has wider crank timing , like the 1/4 thread shaft 19 .
silly picture . Needle @ 6 or 7 turns , according to fuel .
(http://stunthanger.com/smf/index.php?action=dlattach;topic=41828.0;attach=241748;image)
nuther silly picture Empasiseing NOSE DOUBLERS , this in fact runs prettty smooth . Setting props @ 90 deg. to Ea Other @ TDC .
knactually OSes in er in this shot , but the FOX 19 / 25s 'r going back in . Silly Me has Just Bought ANOTHER , youd think TEN would be enough .
(http://stunthanger.com/smf/index.php?action=dlattach;topic=41828.0;attach=241746;image)

You can here em whistling around HERE .https://www.youtube.com/watch?v=SFKjW0tBukk and spot the W Wind ,

Id axidently put some fuel in the nitro , Had to sprint for spanner & screwdiver to refix a prop kicked loose , on W wid , last up .
Definately 15 or 20 % Nitro on something like these gets easier settings , thus better air time .

The Piston Liner is unhardened Leaded Steel , Ive always used 27 % Oil in them .

The 25s I have WILL actually ' switch ' like up & down . Ive some old High A R 10 x 4 woods they like ,
or top flight 8 x 6s or 9 x 4s , Taipan 9x4s , but the Zinger 9 x 5s are as good .