News:




  • November 20, 2017, 10:20:51 AM

Login with username, password and session length

Author Topic: Fox .35 Timing  (Read 1216 times)

Online George Albo

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 281
Fox .35 Timing
« on: August 21, 2017, 03:10:37 PM »
I have recently become interested in the work that Larry Foster and Lew Woolard had done to the Fox .35. I read that Lew Woolard changed the timing on the Fox. Anywaus, does anyone have any information on wfat Lew did, and why? 
Don't sweat the petty things.   Don't pet the sweaty things / :)


Online George Truett

  • 2016 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 86
Re: Fox .35 Timing
« Reply #1 on: August 21, 2017, 03:31:29 PM »
Lew is most well known for his 40s, I know he did 35s as well but I don't know what he did.  Here's the info on his 40 if that's any use to you but a very different beast than the old 35.

Online George Truett

  • 2016 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 86
Re: Fox .35 Timing
« Reply #2 on: August 21, 2017, 03:55:23 PM »
Page 1

Online George Albo

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 281
Re: Fox .35 Timing
« Reply #3 on: August 21, 2017, 08:01:02 PM »
Don't sweat the petty things.   Don't pet the sweaty things / :)

Offline Reptoid

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 157
Re: Fox .35 Timing
« Reply #4 on: August 22, 2017, 05:35:54 PM »
Those mods are for the fox 40 BB, a very different engine than a fox 35 stunt. Just so you're aware
Regards,
       Don
       AMA # 3882

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 7928
Re: Fox .35 Timing
« Reply #5 on: August 22, 2017, 06:00:11 PM »
I have recently become interested in the work that Larry Foster and Lew Woolard had done to the Fox .35. I read that Lew Woolard changed the timing on the Fox. Anywaus, does anyone have any information on wfat Lew did, and why?

  I think Lew was reworking Fox 40 compacts. I don't think there is any reason at all to change the timing on a Fox 35, all the erzatz mods made to other engines like the 40FP are usually intended to replicate the Fox 35 performance.

   There aren't very many useful performance modifications to be made. Aside from the obvious burp fix, increasing the compression is about the only useful modification I know of. Adding nitro is by far the easiest way to increase the performance!

    Just about everything else was geared towards durability or reducing vibration, not improved performance.

    Brett

Online George Albo

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 281
Re: Fox .35 Timing
« Reply #6 on: August 23, 2017, 07:57:08 PM »
  I think Lew was reworking Fox 40 compacts. I don't think there is any reason at all to change the timing on a Fox 35, all the erzatz mods made to other engines like the 40FP are usually intended to replicate the Fox 35 performance.

   There aren't very many useful performance modifications to be made. Aside from the obvious burp fix, increasing the compression is about the only useful modification I know of. Adding nitro is by far the easiest way to increase the performance!

    Just about everything else was geared towards durability or reducing vibration, not improved performance.

    Brett

I have been looking around, reading and acquainting myself with work to extend serviceability of a slew of Fox 35's I have, I got the idea that Lew Woolard had done some retiming from a comment I found mentioned here: https://www.coxengineforum.com/t5556-lew-woolard-fox-35?highlight=lew+woolard

----------------------------
I have since received a reply from the original poster:

George,

That's a pretty simple answer. The timing is not cut at all on the .35. The factory timing was already good for the 4-2-4 stunt run.

If you can get a hold of a stuffer backplate, a California blue magic hemi head and an ST .51 NVA then you pretty much have a Lew Woolard engine. You can have the stock Fox Hemi head cut to match a Blue Magic.

Hope this helps,
Cribbs74
-----------------

Thanks,
George Albo
« Last Edit: August 23, 2017, 09:45:56 PM by George Albo »
Don't sweat the petty things.   Don't pet the sweaty things / :)

Offline Dennis Toth

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1895
Re: Fox .35 Timing
« Reply #7 on: August 29, 2017, 05:52:12 PM »
What are the particulars of the California Blue Magic Head? Who sells it?

I myself like the stock head, HiZoot crank (Randy Smith) and the Randy Smith Fox style NVA (this has the center turned down to match the standard Fox spraybar and give good power without needing to bore out the venture. With the stock head you can use higher % oil (27 - 28) and not overcompress (old diesel trick). I like to run 25% oil Sig 7% nitro (mix equal 5% and 10%) with1% Aero One additive (Randy Smith).

One think I have found that running a muffler on the Fox you need to run a smaller diameter prop (I run a RSM 9x6) to allow a lower heat load. Also if you are going to use Aluminum motor mount pads make up 1/32" plywood crush pads to go between the engine mount lugs and the AL pads. The Fox 29/35 stunt engines have a slight die relief angle so you need to let it have something to get solid with. If you try to pull it down hard on the AL pads without the crush pads it will distort the case and cause binding of the piston/cylinder and give very weird runs. Other option is to have the mounts machined flat.

Best,    DennisT
« Last Edit: September 13, 2017, 05:30:23 PM by Dennis Toth »

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 308
Re: Fox .35 Timing
« Reply #8 on: August 29, 2017, 11:22:32 PM »
The Blue Magic head was what was written down on Lews notes that came with the engine. For all I know it may be just what Lew called it. It has a pronounced hemi combustion chamber and an angled plug like the Fox .15X

When I wrote that post originally I was working off of assumptions. So I just assumed the timing had been cut. Like I mentioned before, if you can find a stock Fox Hemi kit you can have the head milled to correct the defect that Marvin Denny noted, and Fox never heeded.

Lew charged $35 for the .35 plus parts and $40 for the .40 plus parts. Pretty good deal!


Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 7928
Re: Fox .35 Timing
« Reply #9 on: August 30, 2017, 08:29:42 AM »
The Blue Magic head was what was written down on Lews notes that came with the engine. For all I know it may be just what Lew called it. It has a pronounced hemi combustion chamber and an angled plug like the Fox .15X


    It was marketed as the Blue Magic head for a long time back in the early 90's when Tom Muggleton came up with the idea (and had at least 3 different versions).   I vaguely recall that the Blue Magic was either a Muggleton Stage 3 or a close copy, but that could be wrong.  Eric Rule would know/remember for sure.

     The only performance improvement you can make by reasonable mechanical modifications/tweaks is by *increasing* the compression, which suggests the different heads. The improvement will be to permit it to hold a 4-stroke to higher RPM, and increase the effect of the break, which with the stock engine is *extremely gentle* no matter what it sounds like. It's the opposite of a conventional stunt engine, where if you hear something, it really changes a lot. This, the change is largely about the exhaust note changing - the difference between a 4 stroke and a 20stroke is negligible.

   You can blueprint it much like Larry Foster did, but all that does is ensure that it runs properly stock. Almost everything done to it was to improve reliability/durability, not to improve the performance.

    The easiest performance enhancement is still added nitro, that solves several issues at once, although not the most important one, the burp. Fortunately, we know how to fix that now and it's dirt cheap, easy, and there's no reason not to fix it. 

    Brett

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 308
Re: Fox .35 Timing
« Reply #10 on: September 03, 2017, 08:50:48 AM »
    It was marketed as the Blue Magic head for a long time back in the early 90's when Tom Muggleton came up with the idea (and had at least 3 different versions).   I vaguely recall that the Blue Magic was either a Muggleton Stage 3 or a close copy, but that could be wrong.  Eric Rule would know/remember for sure.

     The only performance improvement you can make by reasonable mechanical modifications/tweaks is by *increasing* the compression, which suggests the different heads. The improvement will be to permit it to hold a 4-stroke to higher RPM, and increase the effect of the break, which with the stock engine is *extremely gentle* no matter what it sounds like. It's the opposite of a conventional stunt engine, where if you hear something, it really changes a lot. This, the change is largely about the exhaust note changing - the difference between a 4 stroke and a 20stroke is negligible.

   You can blueprint it much like Larry Foster did, but all that does is ensure that it runs properly stock. Almost everything done to it was to improve reliability/durability, not to improve the performance.

    The easiest performance enhancement is still added nitro, that solves several issues at once, although not the most important one, the burp. Fortunately, we know how to fix that now and it's dirt cheap, easy, and there's no reason not to fix it. 

    Brett


I can think of a couple, laziness and lack of concern.  ;) However, of the 1/2 dozen I own only one has ever had a really pronounced burp. It is a 1954 case with that huge bypass. Maybe one day I will throw a stick in it and see what it does. It doesn't cut out though.


Online Fredvon4

  • 2017
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1241
  • Central Texas
Re: Fox .35 Timing
« Reply #11 on: September 03, 2017, 01:37:10 PM »
I too evaluated the severity of the dreaded Fox .35 burp and decided I did not want to fuss with opening an other wise good engine to make some modification..

Call it lazy, or more to the point frugal...

Everybody got me on track with right fuel and prop... hell, I only ran 3 6oz tanks for bench (break in?) and set that sucker on my 29 oz Ring master and fly it a lot... I do NOT and can NOT fly a Pampa pattern... so the maneuvers that might cause a BURP are not in my kit of triks

I agree that Brett's advice to place the plug is just a sound prophylactic practice... I can not see where it will hurt any thing

BUT if you want to fly a Fox .35 and not fuss with gaskets, leaks, and making a plug of the correct size and any of the self doubt..screw it...get good fuel, good glow plug, proper prop, and go fly the snot out of it...

YOU will know if it Burps and YOU will know if that disturbed you enough to add the proven Burp mod



"A good scare teaches more than good advice"

Fred von Gortler IV

Online Brett Buck

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 7928
Re: Fox .35 Timing
« Reply #12 on: September 03, 2017, 01:52:02 PM »

BUT if you want to fly a Fox .35 and not fuss with gaskets, leaks, and making a plug of the correct size and any of the self doubt..screw it...get good fuel, good glow plug, proper prop, and go fly the snot out of it...

YOU will know if it Burps and YOU will know if that disturbed you enough to add the proven Burp mod

   Maybe you can, but I have seen absolutely endless examples of severe burps and even quits that ended in crashes, and when the pilot comes off the circle, claim it doesn't happen and the engine runs great. Or that "that is just part of learning to fly", or "it is supposed to do that, it's the magic of Fox".

     One nitwit ran up to me at the 2015 NATs after a Fox flight and yelled to challenge my comments - "see how well that ran!!!" This in a Galloping Comedian - with an UPRIGHT ENGINE. 
   
So don't make any rash assumptions about how people can tell when it's wrong (Fox Burps or anything else) and will take steps to fix it. In many cases, they will not recognize the problem, say it's normal, or defend it and call you a communist for suggesting that anything could be done.

    For the record, it is NOT supposed to almost quit or actually on hard outside corners and that is not what a "4-2 break" means. It's supposed to break into a 2-stroke in or shortly after the corner and is should work the same way on insides and outsides - not severely misfire and take 1/2 second (or about the length of the descending leg of the outside square loop) to recover.

     Brett

Offline Ron Cribbs

  • Trade Count: (0)
  • Commander
  • ****
  • Posts: 308
Re: Fox .35 Timing
« Reply #13 on: September 03, 2017, 05:35:48 PM »
Hey Brett,

No doubt with your experience you have seen a lot. I agree that it won't hurt anything to do it. While my flying skills are not steller I can get through a recognizable pattern. Enough to induce the burp. I could be just lucky in that I have never had a flame out. I was speaking of my own experience. Others may vary, I assume it is a real problem as it comes up quite a bit.

Certainly not discounting the idea entirely. Like I said I do have one that burps more than I would like. I'll do the mod and see what happens with it.

Ron

Offline Matt Spencer

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 2573
Re: Fox .35 Timing
« Reply #14 on: September 04, 2017, 01:05:43 AM »
You Guys are TO FAR NORTH .  ;D

The Further South you go , the Better they Run . :!



If You LIVE UP NORTH , you need a OS 35 . ;)



 :-X
Somebody who didnt know , would think the vee verr vee verr engine run was off / sour - incorrect . It should run even all the time , shouldnt it .  >:D

Offline Dennis Toth

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1895
Re: Fox .35 Timing
« Reply #15 on: September 13, 2017, 06:16:02 PM »
Depending on what level of competition you compete in the Fox is a good stunt engine if you understand its limits. Stock it likes upright or inverted engine positions. Since most of us run mufflers this puts stress on the Fox 35. It holds heat which causes erratic runs if you try to run it like they did open face on a 10x6 wide blade prop. With the muffler, you need to drop the diameter. I have been using the down tilt Fox muffler on my El Diablo with a 9x6.7 RMS prop (I heat pitch the wood prop up from a 6" pitch just like you do to an APC or CF prop). With the muffler the Fox will pull a 42 - ~47" span ship that weighs in around 32 - 38 oz ish just fine.

It won't be that great in a front row finished Nobler with the muffler. It likes 26 - 28% oil and moderate nitro (I have had good success with 7%). Also it likes maple mounts or it you use the Aluminum pads put the 1/32" crush pad between the engine lug and the Al mount pad and it is fine. Last, if you change the head bolts from the stock Philips bolts for socket heads and you are using the stock head you need to turn down the bolt head diameter to match (or even a few thou less) the stock bolts. Not doing this will cause the head to distort as you tighten it down and cause binding and erratic running (I also like to run one drill size drill through the bolt hold just to give a little space). It's a good stunt engine within limits.

Best,   DennisT

Online George Albo

  • 2017
  • Trade Count: (0)
  • Commander
  • *
  • Posts: 281
Re: Fox .35 Timing
« Reply #16 on: September 14, 2017, 05:18:50 PM »
Depending on what level of competition you compete in the Fox is a good stunt engine if you understand its limits. Stock it likes upright or inverted engine positions. Since most of us run mufflers this puts stress on the Fox 35. It holds heat which causes erratic runs if you try to run it like they did open face on a 10x6 wide blade prop. With the muffler, you need to drop the diameter. I have been using the down tilt Fox muffler on my El Diablo with a 9x6.7 RMS prop (I heat pitch the wood prop up from a 6" pitch just like you do to an APC or CF prop). With the muffler the Fox will pull a 42 - ~47" span ship that weighs in around 32 - 38 oz ish just fine.

It won't be that great in a front row finished Nobler with the muffler. It likes 26 - 28% oil and moderate nitro (I have had good success with 7%). Also it likes maple mounts or it you use the Aluminum pads put the 1/32" crush pad between the engine lug and the Al mount pad and it is fine. Last, if you change the head bolts from the stock Philips bolts for socket heads and you are using the stock head you need to turn down the bolt head diameter to match (or even a few thou less) the stock bolts. Not doing this will cause the head to distort as you tighten it down and cause binding and erratic running (I also like to run one drill size drill through the bolt hold just to give a little space). It's a good stunt engine within limits.

Best,   DennisT

Thanks for the insights. I'm attached to my Fox 35's since I ran my first on about 40 years ago.
George Albo
Don't sweat the petty things.   Don't pet the sweaty things / :)

Offline Dennis Toth

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1895
Re: Fox .35 Timing
« Reply #17 on: September 15, 2017, 06:24:28 PM »
George,
Sounds like you and me have been in the hobby about the same amount of years. I too like the Fox 35 especially for OTS, it just makes me happy, nuff said.

Best,    DennisT


Tags: