News:


  • June 15, 2024, 01:39:11 PM

Login with username, password and session length

Author Topic: Fox 19  (Read 954 times)

Offline Bill Smith

  • 21 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 256
Fox 19
« on: April 22, 2008, 07:50:46 PM »
OK I've got a super clown and I put a old fox 19 on it. To get right to it, there is plenty of power but a REAL bad fox burp and it doesn't like being inverted (moving the tank was no help). I haven't torn into it yet but I'm thinking of filling up part of the intake port.
Any suggestions will be helpful.

Offline Just One-eye

  • Another Old Fart
  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 198
Re: Fox 19
« Reply #1 on: April 22, 2008, 08:54:35 PM »
The only Fox engine of mine, out of maybe three dozen the past 55 years or so, that ever "burped" some was a newish 35 stunt (newer than most of my pre-1970 oldies, anyway).  The 3-bolt 19 and its 25 size sibling not only never burped (and I've had quite a few of those, at least three of each, probably more, when they were still being made), they offered better power to weight than the 29 and 35 did.  The old 35s didn't burp unless matched to a bad tank, and the 19 and the 25 definitely quality as old.  Fox stopped making those before 1970 (the 25 was out of production before 1965). 

I think you have a bad tank.  Classic style 4-2-4 engines do not like a great many "profile" tank designs that newer engines run fine with (including OS Max-S 35s, Max-H 40s, and Johnson "S" engines, to name another trio).

Offline Bob Zambelli

  • 21 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 850
Re: Fox 19
« Reply #2 on: April 23, 2008, 09:34:46 AM »
I'm with J.O.e. on this one.

Although I have not run a Fox 19 in many years, I have never experienced the burp with my stunt 35s.

It could be because of my tank setup - I NEVER run uniflow on any engines.
All my tanks are the traditional metal VECO type wedge and vented the same - to the inboard front upper corner.

Two stroke, four stroke, profile upright, with or without muffler pressure, same setup.

The only time I broke tradition was on my SAITO 30 powered Argus. On that, I had to go to my Eagle Hopper design but still, no uniflow.

Also, I run the stock needle valves on all my Fox engines.

Bob Z.

Offline dave siegler

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1134
  • sport flier
    • Circlemasters Flying club
Re: Fox 19
« Reply #3 on: April 23, 2008, 09:59:18 AM »
OK I've got a super clown and I put a old fox 19 on it. To get right to it, there is plenty of power but a REAL bad fox burp and it doesn't like being inverted (moving the tank was no help). I haven't torn into it yet but I'm thinking of filling up part of the intake port.
Any suggestions will be helpful.

Is it the 3 bold, the 4 bolt or the newer one? 
Dave Siegler
NE9N extra class
AMA 720731
EAA 1231299 UAS Certificate Number FA39HY9ML7  Member of the Milwaukee Circlemasters. A Gold Leader Club for over 25 years!  http://www.circlemasters.com/

Offline RandySmith

  • Administrator
  • Trade Count: (0)
  • Admiral
  • *****
  • Posts: 13747
  • Welcome to the Stunt Hanger.
    • Aero Products
Re: Fox 19
« Reply #4 on: April 23, 2008, 10:29:03 AM »
OK I've got a super clown and I put a old fox 19 on it. To get right to it, there is plenty of power but a REAL bad fox burp and it doesn't like being inverted (moving the tank was no help). I haven't torn into it yet but I'm thinking of filling up part of the intake port.
Any suggestions will be helpful.


HI Bill

I ran many older FOX 19s and FOX 25s without any "burp" problem on profiles or upright.  A few questions,
what type of tank?
How far is the tank from the motor?
are you running this engine very lean or very rich?
have you changed glow plugs?
what fuel are you using?
what prop are you turning?

It maybe beneficial  to go back out and try this again with the tank as close to the engine as you can get it, and a new hot glow plug, I would not take the motor apart for modifying untill I found the problem.

Randy

Offline L0U CRANE

  • AMA Member
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1076
Re: Fox 19
« Reply #5 on: April 23, 2008, 11:08:43 AM »
Bill,

I'll presume your Fox 19 is the 4-bolt backplate, bolt-on venturii type?

This one likes to rev, and does so very happily. At good RPM, it draws fuel well. If your prop is too much load, it might not get 'on its step.'

(Reason for my guess: The old 3-bolt backplate Fox 19s are very rare, now. The newer Fox 25BB Schnuerle came about as a stretch from a 19BB Schneurle, that but isn't in production. ..was only produced a few years...)

So, try 15% nitro (or more) with total oil around 25%, all or mostly castor. Around 9-4, 8-6 props should let it unload.
\BEST\LOU

Offline Bill Smith

  • 21 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 256
Re: Fox 19
« Reply #6 on: April 23, 2008, 04:53:46 PM »
Its is an older 3 bolt and is running a perfect 1 3/4 oz wedge tank and a zingler 8x6 wood prop so I don't think I loading it. Now i should have stated (sometimes thinking is tough) that it is an RC engine converted to a venturi. the diameter of the venturi is 15/64. with a tiger needle. I would think that this combo would not allow for great air flow and the draw should be fairly strong. Compression seems very good and I have tried two tanks but the 2-4 is wide and it burps when i pull outsides and sometimes dies inverted. I have yet to tear it down, maybe I have a leak in the backplate gasket or the venturi, but it  does have an o-ring.

Offline Ray

  • Trade Count: (0)
  • Lieutenant
  • ***
  • Posts: 99
Re: Fox 19
« Reply #7 on: April 23, 2008, 05:42:41 PM »
The Kap-Pak & Perfect tanks were not particularly good when new (as old as they all are now, chances are both you've tried have splits in the plumbing inside).  Get one of the recently produced clones of a Veco tank, 2 Ounce through 2 1/2 size, from Brodak, Eric Rule, or SIG.

Offline Bill Smith

  • 21 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 256
Re: Fox 19
« Reply #8 on: April 24, 2008, 07:26:20 PM »
OK my very good friend Gerry has come up with a brand new old stock CL Fox .19 case. I have swapped every thing out, checked for leaks and mounted it and a NEW tank on the plane. Now all I need is time and weather to try them out.

Offline Bill Smith

  • 21 supporter
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 256
Re: Fox 19
« Reply #9 on: May 01, 2008, 04:19:14 PM »
Just got out and tried it today and yes it works fine now I don't know what helped more the new tank or the new case but no burp and no stall.  I think I can see a crack in the old case, which might explain the wide 2x4 and burp but the inverted problem may have been the tank I haven't opened it up yet to find out yet.
Thanks to all who tried to help (I need all I can get).


Advertise Here
Tags:
 


Advertise Here