News:


  • March 28, 2024, 05:22:08 PM

Login with username, password and session length

Author Topic: Fox 35 Hemi Kit  (Read 3336 times)

Offline Mark Mc

  • 24 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 718
Fox 35 Hemi Kit
« on: May 01, 2018, 06:37:45 PM »
A couple of weeks ago, as I was heading home from the field, I stopped in at the old hobby shop on that side of town.  It's a shop that's been open for something like 70 years, and when I stepped in I was shocked.  All the floor racks had been removed and boxes were everywhere.   one wall was bare and the remaining shelves were half empty.  I knew a new owner had bought the place, but this was dismaying.  I asked the guy behind the counter what they were planning on doing with the shop.  "More drones and ARFs."  *** SIGH ***

The large parts drawer cabinet that used to be behind the counter was on the floor, so I started digging through the drawers for things that I might someday need.  I bought every Cox part that they had (all of which were labeled at 1960's-1970's prices).  In the Fox drawer were a bunch of fuel nipples and such that I had no need of.  But there was a Fox 35 Hemi kit in the drawer.  I don't know what a Hemi kit is worth, but I splurged and bought it for $28 bucks.

Being a youn'un and not familiar with the ins and outs of the Fox 35, I tried a search of the forum to see what the pros and cans of the Hemi kit are for a 35.  I didn't find any discussions specifically about the Hemi kit, just mentions of it in other threads.  Some saying the kit is useful, some saying the kit adds nothing noticeable.  Can someone enlighten me about the usefulness of the kit?  Is the backplate the one they call a stuffer backplate?  Does the head do anything noticable on the engine?  I have a new 60th Anniversary Fox 35 engine.  Is there any reason to put the kit on the 60th engine?  Would it help on one of the two well-used Fox 35's I have?  How would I know which to put it on, if so?

Mark

Online kenneth cook

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1464
Re: Fox 35 Hemi Kit
« Reply #1 on: May 01, 2018, 07:18:44 PM »
              Mark, your going to get mixed opinions on this. If it's a Fox hemi kit, the stuffer backplate is a must. Reason being is that it's a machined backplate and not a casting. This means, the gasket seals better and the ears aren't being subjected to bending like the cast version. This doesn't mean that it won't bend, you just snug these down. I prefer Fel-Pro gasket material over the cork but that's my preference. The main importance is the fact that the rod doesn't always stay properly on the crank pin. The stuffer back plate is hard anodized in the event of a rub and it protrudes more into the case over the stock version assisting the rod.

             Some will say the hemi adds more power, I don't buy that statement. In fact it lowers the already low compression engine even further. I personally wouldn't use any head gaskets if you choose to use the hemi head, just lap the top of the steel liner.  The head was never fully finished when Marvin Denny designed it and he would finish it for you if you sent it to him. It makes the engine harder to start and I have done extensive back to back tests using the stock, Fox hemi, L&J head and found the stock to always work better. The stuffer backplate does seem to boost performance. Nothing indexes the button so you must be careful that the baffle of the piston doesn't strike the head. There's very little clearance.

             The problem with the Fox is that the crank can develop a lot of run out in the shaft bearing. Not always a bad thing with a old engine because a worn one runs the best. However, seeing you have a new 60th, that would be the engine I would put it on. The other problem is this, the Fox case is like a eggshell, the older ones are even worse. If you tighten one screw incorrectly, you will dial a bind into the liner that could really FUBAR your engine if ran. I would leave the old engines as is and not compromise the carbon/castor goo that's sealing the head.

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 9920
Re: Fox 35 Hemi Kit
« Reply #2 on: May 10, 2018, 05:01:23 PM »
 "Nothing indexes the button so you must be careful that the baffle of the piston doesn't strike the head. There's very little clearance."

The one I have has a split pin pressed into one part of the head and indexes to a hole in the other half. I can't recall which side has the pin pressed in, and which has the clearance hole right now. If your kit doesn't have the indexing pin, a little fussing with the button with piston at TDC and some scribe marks should get the button located safely.  D>K Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Balsa Butcher

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2357
  • High Desert Flier
Re: Fox 35 Hemi Kit
« Reply #3 on: May 11, 2018, 04:46:30 PM »
Only thing I have to add is back in the day when I was using Fox 35s more I had three different versions of the hemi-head. Of the three I liked the factory hemi-head the best. It ran the strongest 4x2 break. All of them ran better with the stuffer backplate. I'd say it is a "score!"  8)
Pete Cunha
Sacramento CA.
AMA 57499

Offline Onelife

  • 22 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 54
Re: Fox 35 Hemi Kit
« Reply #4 on: November 07, 2022, 11:34:12 AM »
Where can I fine the kit backplate and head ?

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6824
Re: Fox 35 Hemi Kit
« Reply #5 on: November 07, 2022, 11:47:24 AM »
Where can I fine the kit backplate and head ?

  You just have to luck into them. Watch the control line web sites and classifieds, and eBay also. They have not been made in years. Some enterprising young machinist could possibly make a spare buck or two by filling in this gap.

   Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Onelife

  • 22 supporter
  • Trade Count: (0)
  • Lieutenant
  • *
  • Posts: 54
Re: Fox 35 Hemi Kit
« Reply #6 on: January 14, 2023, 05:13:32 PM »
Hopefully someday I will run into one.  I would even like to see a picture of one   

Offline Allen Eshleman

  • Trade Count: (0)
  • Captain
  • *****
  • Posts: 809
Re: Fox 35 Hemi Kit
« Reply #7 on: January 16, 2023, 08:36:12 AM »
You could put a WTB (want to buy) on the Stunthanger Classifieds for the stuffer plate.

Offline Mark Mc

  • 24 supporter
  • Trade Count: (0)
  • Captain
  • *
  • Posts: 718
Re: Fox 35 Hemi Kit
« Reply #8 on: January 16, 2023, 12:39:34 PM »
HI Mark. If that hobby shop is that old, they may still have some real silk span in stock. Ask, it is impossible to find anymore and worth it to find some. Just saying. H^^

Ty, I moved from Portland a year ago, so I have no way of checking that old hobby shop.

Mark

edit:  I just checked the shop's website and they are out of business.  Ah, well.  I did not think they would survive when they decided to specialize in what could be simply ordered online.

Offline Peter in Fairfax, VA

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1101
Re: Fox 35 Hemi Kit
« Reply #9 on: January 23, 2023, 09:30:02 PM »
I am looking through Fox parts I plan to sell now.  I believe I have hemi heads from Fox:  two pieces, a button and a clamp, essentially.  Not sure what the stuffer backplates are like.  I'll look if I have a clue as to what to look for.

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6824
Re: Fox 35 Hemi Kit
« Reply #10 on: January 23, 2023, 09:56:45 PM »
I am looking through Fox parts I plan to sell now.  I believe I have hemi heads from Fox:  two pieces, a button and a clamp, essentially.  Not sure what the stuffer backplates are like.  I'll look if I have a clue as to what to look for.

  Hi Peter,
   That sounds like the Fox Hemi head. None of the others are two piece, that I know of. The stuffer back plate will have smooth, machined surfaces with sharp corners, unlike the stock rear cover that is a cast piece, with roundish and curved surfaces. The stuffer plate is usually anodized also and will have a blackish surface towards the crank shaft that is a Teflon coating for the rod journal and crank pin to run against when starting the engine. If none of that makes sense to you, send me your email address and I'll send you some pictures.
  Type at you  later,
    Dan McEntee
« Last Edit: January 25, 2023, 04:18:18 PM by Dan McEntee »
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Offline Peter in Fairfax, VA

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1101
Re: Fox 35 Hemi Kit
« Reply #11 on: January 24, 2023, 10:51:47 AM »
I have a bunch of Fox, Super Tigre, Cox, Rossi and O.S. I am going through now.  I'll look for the machined Fox .35 backplates.

Offline Steve Helmick

  • AMA Member and supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 9920
Re: Fox 35 Hemi Kit
« Reply #12 on: January 25, 2023, 12:40:10 PM »
I have a bunch of Fox, Super Tigre, Cox, Rossi and O.S. I am going through now.  I'll look for the machined Fox .35 backplates.

The backplate you are looking to ID is also hard anodized, so has a dark olive grey color. May be easier to spot.  D>K Steve
"The United States has become a place where professional athletes and entertainers are mistaken for people of importance." - Robert Heinlein

In 1944 18-20 year old's stormed beaches, and parachuted behind enemy lines to almost certain death.  In 2015 18-20 year old's need safe zones so people don't hurt their feelings.

Offline Peter in Fairfax, VA

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 1101
Re: Fox 35 Hemi Kit
« Reply #13 on: January 26, 2023, 07:13:15 PM »
I have three sets:  The black anodized machined backplate, the head button, the head clamp.  Will take me about ten days to determine price.

Peter

Offline Howard Rush

  • 22 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 7805
Re: Fox 35 Hemi Kit
« Reply #14 on: January 26, 2023, 08:23:56 PM »
If your engine is broken in, you’ll probably do more harm than good by unbolting the head and retightening the bolts, whether or not you upgrade the head.
The Jive Combat Team
Making combat and stunt great again

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6824
Re: Fox 35 Hemi Kit
« Reply #15 on: January 26, 2023, 10:32:06 PM »
If your engine is broken in, you’ll probably do more harm than good by unbolting the head and retightening the bolts, whether or not you upgrade the head.

    A long, long time ago, Gary Frost taught me that if I were to ever take a Fox .35 apart, the first thing to do was to take a 4-40 bottoming tap and chase all the threads, and I was amazed at how much metal came out of the holes. Duke was never one to throw out a worn tap until it was absolutely useless. New engines were to be considered as kits engines. Before turning them over, take them apart and remove any debris you may find, chase all the holes with a 4-40 bottoming tap and then re-assemble if no other types of work were going to be done. Back plate gasket was replaced with a gasket made from old playing cards. If you work slowly and pay attention to how much effort it takes to dis-assemble one, and then compare what it takes to reassemble, it is a significant difference in resistance in the threads. You can install the screws and run them down until they just stop,  then go back around and retorque them. Been doing all of my Fox .35's that way since I met Gary and he told me this back in the late 1970's, or early 80's.
  Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)


Advertise Here
Tags:
 


Advertise Here