Notices
Glow Engines Discuss RC glow engines

Club FOX!

Old 08-19-2014, 08:11 AM
  #3576  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Originally Posted by Hobbsy
I remember that Dar Zeelon had a fit when I told him that my Fox .74 ABC had no pinch, he swore that it would never be any good. I think that pinch is way over rated. My LA's don't have much of it either.
Without getting into plating 101, I've not heard or felt first hand a "tight" nickel plated liner. Brass and aluminum liners, yes. Car engines are notoriously tight and they're all ABC. I think in regard to the Foxes; perhaps the pistons are lapped closer to an optimum fit like the common ABN variety. Of course Foxes are test run at the factory so it's somewhat deceiving as to how they felt when totally unrun. Pinch isn't everything, I agree to a point however. Dub Jett said on one of his FAQ pages in regard to break-in and running his engines stated something to the tune of "ABC and AAC engines run better and produce more power when they are tight, and by the time there is no "pinch" left (bump at top dead center) the engine is starting to lose some of its power."

So I'm of the bias that a very low/no run time engine with an ABC or AAC cylinder should be snug. Mine have a pinch but they're easily turned over without a prop; glow plug or not. I'm sure it will run fine and last a long time but likely won't produce the power it's capable of if it had a tighter fit. I'm not complaining mind you. Just adding my thoughts and understandings albeit more limited than others here.

To be fair, your LA engines are in a different class compared to a Fox, IMO.

Last edited by 1QwkSport2.5r; 08-19-2014 at 08:13 AM.
Old 08-19-2014, 10:10 AM
  #3577  
hsukaria
 
Join Date: Feb 2007
Location: Dearborn, MI
Posts: 3,216
Received 1 Like on 1 Post
Default

Regarding the Fox looks, you should check out their newest carb, it is a beauty (and functions perfectly). That might cure your carb needle issues too, Tim. I know it won't be vintage, but you will love the looks and performance with the new carb.

My Fox 74 ring engine also has super high compression that it feels like an ABC. When I flip the prop, you also have to move your finger out of the way or it will get smacked. The 74, according to the article by Clarence Lee that is always quoted around here, has higher compression than the Fox 60. That is why you have to run LOW nitro fuel (5% max) on it. That is even after getting the new head button plus 2 head shims.

I recently had to dump a nickel-plated engine because the liner peeled after an accidental lean run. Some dirt got in the fuel and clogged the carb (my fault of course). While the plane was flying, the carb got clogged and leaned out, causing the liner to peel. I couldn't cut the engine because it was on a plane that cannot dead-stick. There was still some pinch at TDC (less than originally), but as the engine warmed up, the compression is lost, and engine would quit. Normally, I would repair/replace the damaged part, but this brand of engine's spare parts are so expensive, that I decided to switch over to a used 4-stroke glow instead.
Old 08-19-2014, 10:16 AM
  #3578  
Hobbsy
My Feedback: (102)
 
Hobbsy's Avatar
 
Join Date: Dec 2001
Location: Colonial Beach, VA
Posts: 20,370
Likes: 0
Received 24 Likes on 24 Posts
Default

When I say little pinch, the Fox .74 and the LA's, a .46 and a .65 will gently push the sleeve up out of the block but very little finger pressure will hold it down. I know all that is subjective, I had a Zeus .61 that nothing short of having the head on would hold it down. So many variations of our toy stuff.
Old 08-19-2014, 10:20 AM
  #3579  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

H - the Fox parts factory doesn't have any spare parts. Been looking on the auction site for Fox carbs and am coming up empty. I need to .312" carbs for my Twin and I need one for my .46BBRC. The 50BB has an MkX .330" carb on it which might be a bit large for its rev range too.

The MkX carbs are good carbs, this old one has just seen better days. I'll mess with the detents and put some Teflon tape on the needles threads. Should clear up most of the touchy needle problem. The biggest problem with these carbs (MkX) is the coarse threads on the needles.
Old 08-19-2014, 11:12 AM
  #3580  
hsukaria
 
Join Date: Feb 2007
Location: Dearborn, MI
Posts: 3,216
Received 1 Like on 1 Post
Default

Originally Posted by 1QwkSport2.5r
H - the Fox parts factory doesn't have any spare parts. Been looking on the auction site for Fox carbs and am coming up empty. I need to .312" carbs for my Twin and I need one for my .46BBRC. The 50BB has an MkX .330" carb on it which might be a bit large for its rev range too.

The MkX carbs are good carbs, this old one has just seen better days. I'll mess with the detents and put some Teflon tape on the needles threads. Should clear up most of the touchy needle problem. The biggest problem with these carbs (MkX) is the coarse threads on the needles.

My only experience with Fox carbs is the new TN carb and the EZ carb. I like both a lot. The EZ carb has been sitting in a baggy for the last 3-4 years and froze up from the castor oil I suppose. But it is still good otherwise.

Bummer about the Fox Manuf. not producing more engines!!! I was going to rebuild an old classic pattern Phoenix 8 plane I bought used and put the Fox 74 in it with a Jett muffler. I wonder if I should just store the engine away for posterity instead.
Old 08-19-2014, 11:26 AM
  #3581  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Originally Posted by hsukaria
My only experience with Fox carbs is the new TN carb and the EZ carb. I like both a lot. The EZ carb has been sitting in a baggy for the last 3-4 years and froze up from the castor oil I suppose. But it is still good otherwise.

Bummer about the Fox Manuf. not producing more engines!!! I was going to rebuild an old classic pattern Phoenix 8 plane I bought used and put the Fox 74 in it with a Jett muffler. I wonder if I should just store the engine away for posterity instead.
Barring a bad crash, rings and bearings are readily available. Put a couple Bowman rings on the shelf as spares and run the snot out of it.

I've not used the new TN carb, and I have not ran the .46 with the EZ carb yet either. So my Fox experience is limited to the MkX carb which is an auto-mixture carburetor much like the newer TN carb. I'm not a fan of the butterfly Carburetors on my Twin at all.
Old 08-19-2014, 01:08 PM
  #3582  
hsukaria
 
Join Date: Feb 2007
Location: Dearborn, MI
Posts: 3,216
Received 1 Like on 1 Post
Default

Originally Posted by 1QwkSport2.5r
Barring a bad crash, rings and bearings are readily available. Put a couple Bowman rings on the shelf as spares and run the snot out of it.

I've not used the new TN carb, and I have not ran the .46 with the EZ carb yet either. So my Fox experience is limited to the MkX carb which is an auto-mixture carburetor much like the newer TN carb. I'm not a fan of the butterfly Carburetors on my Twin at all.
Yeah, I heard crazy stories about the butterfly carbs. You might have to cheat and put some Perry or OS carbs. (watch me get tossed out of this forum).

I received good help on the EZ carb from the guys in this forum when I first got the 74. The instructions say to start with the air bypass set in the middle. Some advocated to try with the air bypass completely shut and that way you only open the least amount of air bypass for idling. That helps with the fuel suction into the carb.

Last edited by hsukaria; 08-19-2014 at 01:22 PM.
Old 08-19-2014, 02:26 PM
  #3583  
Charley
My Feedback: (2)
 
Join Date: Dec 2001
Location: Kerrville, TX
Posts: 2,127
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by 1QwkSport2.5r
Ran the little lapped .40 for a bit today. I didn't have much time to run it but got it dialed in almost perfect in that time. I had to swap the original high speed needle back in; the end was too long (and narrower) and required being nearly seated to get it into the sweet spot. The old needle had a shorter and thicker tapered end. It idled happily at 2,500 for as long as I let it, but would tick over nicely at 2,100. It throttles pretty nice, though there is a little false needle setting I'm sorting out. Even with tubing on the needle, it still leaks a bit and allows the mixture to change if I bump it causing the rpm to drop (rich). I think the detent clips need to be tweaked and that should help. I'll run more props on it when I get time. It peaked at 13,750 on a 10x5 and FAI fuel today. Pretty consistent in peak revs given the swings in climate lately.
Great, glad you're getting there! I usually put tubing on both needles; the threads are pretty coarse, allowing air in and it helps to hold settings.

CR
Old 08-19-2014, 03:44 PM
  #3584  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Originally Posted by Charley
Great, glad you're getting there! I usually put tubing on both needles; the threads are pretty coarse, allowing air in and it helps to hold settings.

CR
Air doesn't leak in. Fuel leaks out at the needle valve. Remember the fuel system is pressurized.
Old 08-19-2014, 05:32 PM
  #3585  
earlwb
 
earlwb's Avatar
 
Join Date: Aug 2009
Location: Grapevine, TX
Posts: 5,993
Likes: 0
Received 3 Likes on 3 Posts
Default

+1, yes the fuel leaks out. The tubing helps to keep the needle centered better for ease of adjustment if the detents are loose.
Old 08-20-2014, 02:22 PM
  #3586  
Charley
My Feedback: (2)
 
Join Date: Dec 2001
Location: Kerrville, TX
Posts: 2,127
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by 1QwkSport2.5r
Air doesn't leak in. Fuel leaks out at the needle valve. Remember the fuel system is pressurized.
Either way, the tubing should stop it. I've never had a engine with just muffler pressure leak fuel at the needles.

What kind of pressurization are you running?

CR

Last edited by Charley; 08-20-2014 at 02:25 PM.
Old 08-20-2014, 02:49 PM
  #3587  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Originally Posted by Charley
Either way, the tubing should stop it. I've never had a engine with just muffler pressure leak fuel at the needles.

What kind of pressurization are you running?

CR
I run regular muffler pressure on all of my engines except one or two (no muffler). Some of my Super Tigre, both K&Bs, and my Enya .30 all leak a little fuel from the needle.. My ST S29 is probably the worst. They do not have O-rings in the needle holders or on the needles themselves like other companies do. At least not on the Carburetors I have.
Old 08-22-2014, 11:46 AM
  #3588  
hsukaria
 
Join Date: Feb 2007
Location: Dearborn, MI
Posts: 3,216
Received 1 Like on 1 Post
Default

Originally Posted by 1QwkSport2.5r
I run regular muffler pressure on all of my engines except one or two (no muffler). Some of my Super Tigre, both K&Bs, and my Enya .30 all leak a little fuel from the needle.. My ST S29 is probably the worst. They do not have O-rings in the needle holders or on the needles themselves like other companies do. At least not on the Carburetors I have.
For the engine that I just dumped for peeled cylinder liner, it had an o-ring on the HSN. This o-ring got sliced once when it somehow expanded and then got cut by the spraybar. Anyway, the engine ran terrible after that, but I suppose it must have been because the needle would rotate from the vibrations and lean out. The LHS had those o-rings in stock and was an easy fix.
Old 08-22-2014, 12:28 PM
  #3589  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Some manufacturers use o-rings on the needles and some don't. I assume the engines that don't were designed at point in time where most folks didn't use muffler pressure. Some of the mufflers that came with some of my engines were not tapped for pressure but had the location cast into the muffler for it to be added. The engines that I run without pressure need the needle opened 1-1.5 turns further open; fuel consumption is up slightly. My .60 4-stroke picks up several hundred rpm if pressure is used but I don't have a good fitting muffler for that engine.

Conversely, my RC car engines won't run (even idle!) without pressure. The carburetor on my .28 monster truck engine has a 9.2mm carb choke.
Old 08-22-2014, 12:37 PM
  #3590  
hsukaria
 
Join Date: Feb 2007
Location: Dearborn, MI
Posts: 3,216
Received 1 Like on 1 Post
Default

Originally Posted by 1QwkSport2.5r
Some manufacturers use o-rings on the needles and some don't. I assume the engines that don't were designed at point in time where most folks didn't use muffler pressure. Some of the mufflers that came with some of my engines were not tapped for pressure but had the location cast into the muffler for it to be added. The engines that I run without pressure need the needle opened 1-1.5 turns further open; fuel consumption is up slightly. My .60 4-stroke picks up several hundred rpm if pressure is used but I don't have a good fitting muffler for that engine.

Conversely, my RC car engines won't run (even idle!) without pressure. The carburetor on my .28 monster truck engine has a 9.2mm carb choke.
This also brings up the issue of old engines using crankcase pressure. You don't see that in new engines anymore. Is that because old engines didn't have mufflers, but sometimes needed a pressurized fuel system? My older Fox 74 Eagle IV has a bump cast into the backplate to allow for drilling a pressure nipple. Mine is pre-drilled almost all the way through. The newer Fox Eagles that I have seen just have the bump, but not pre-drilled since that mode of pressurization is not common anymore.
Old 08-22-2014, 02:09 PM
  #3591  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

If you use crankcase pressure, I think you need a regulator or check valve or something to prevent the negative pressure pulse from creating a momentary vacuum in the tank, I think?
Old 08-22-2014, 02:46 PM
  #3592  
Sport_Pilot
 
Sport_Pilot's Avatar
 
Join Date: Jan 2002
Location: Acworth, GA
Posts: 16,916
Likes: 0
Received 1 Like on 1 Post
Default

Originally Posted by 1QwkSport2.5r
If you use crankcase pressure, I think you need a regulator or check valve or something to prevent the negative pressure pulse from creating a momentary vacuum in the tank, I think?
Most were on the bottom under the crankshaft port. The port would be open only when the crankcase was under pressure. This produced a lot more pressure than muffler pressure. Most were used for control line and so for wide open throttle only the needle was required, no regulator.
Old 08-22-2014, 04:48 PM
  #3593  
Charley
My Feedback: (2)
 
Join Date: Dec 2001
Location: Kerrville, TX
Posts: 2,127
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by 1QwkSport2.5r
I run regular muffler pressure on all of my engines except one or two (no muffler). Some of my Super Tigre, both K&Bs, and my Enya .30 all leak a little fuel from the needle.. My ST S29 is probably the worst. They do not have O-rings in the needle holders or on the needles themselves like other companies do. At least not on the Carburetors I have.
You should check the O-rings if that's the truth. I have K&B, ST, YS, Saito, OS, etc, engines. They all have O-rings on the HS needles, at least. Caveat; dunno about the Chinese ST engines, all mine are Saturno.

CR
Old 08-22-2014, 04:59 PM
  #3594  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

The needles that leak on my engines don't have o-rings to start with, I'll pull some needles off and snap photos for the inquiring minds..
Old 08-23-2014, 05:21 AM
  #3595  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

Here's an Enya .15-IV TV with a leaky needle valve.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	55
Size:	2.10 MB
ID:	2024935  
Old 08-23-2014, 08:44 AM
  #3596  
Charley
My Feedback: (2)
 
Join Date: Dec 2001
Location: Kerrville, TX
Posts: 2,127
Likes: 0
Received 0 Likes on 0 Posts
Default

Put a new O-ring on it.

CR
Old 08-23-2014, 10:02 AM
  #3597  
Cougar429
Senior Member
My Feedback: (3)
 
Cougar429's Avatar
 
Join Date: Apr 2008
Location: Tecumseh, ON, CANADA
Posts: 1,229
Likes: 0
Received 1 Like on 1 Post
Default

Wow! Looking at those head screws would guess that one has been apart a few times.
Old 08-23-2014, 12:15 PM
  #3598  
Broken Wings
My Feedback: (20)
 
Broken Wings's Avatar
 
Join Date: Jan 2003
Location: Cocoa, FL
Posts: 2,090
Likes: 0
Received 5 Likes on 4 Posts
Default

Originally Posted by Cougar429
Wow! Looking at those head screws would guess that one has been apart a few times.
The wrong tool was used...

"Most people and companies outside of Japan have absolutely no idea what they are. With the similarity in appearance to the Frearson and the Phillips the screws are often damaged in removing and installing with the wrong tools. JIS tends not to camout like Philips. The JIS driver can be used on Phillips quite easily but not reciprocally. "

I've been called a "Feckless Fool" for waiting to obtain the correct screw driver to remove the backplate of my Fox Eagle 60 as the instructions call out the correct tool to use.

This was what I was trying to avoid....




http://www.instructables.com/id/When...rial-Standard/
Attached Thumbnails Click image for larger version

Name:	Enya Engine Screw Heads Distroyed.jpg
Views:	212
Size:	2.10 MB
ID:	2024997  

Last edited by Broken Wings; 08-23-2014 at 12:54 PM. Reason: added link
Old 08-23-2014, 12:30 PM
  #3599  
1QwkSport2.5r
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,409
Received 76 Likes on 69 Posts
Default

I know the wrong tool was used. The engine came to me like you see in the picture. Auction site special! Since the screws need to be replaced, I'll use socket head cap screws instead which are more common.
Old 08-23-2014, 12:34 PM
  #3600  
Cougar429
Senior Member
My Feedback: (3)
 
Cougar429's Avatar
 
Join Date: Apr 2008
Location: Tecumseh, ON, CANADA
Posts: 1,229
Likes: 0
Received 1 Like on 1 Post
Default

I almost always replace fasteners with allan head cap screws. Makes for a much simpler installation and consistent clamping torque. Ball end drivers make access less of a problem, as well.

I have also found most screw fasteners to be much softer material and easier to damage.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.