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Engine basics => Engine set up tips => Topic started by: BillP on July 20, 2021, 01:08:12 PM
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I just called Brodaks to order a Big Art tongue muffler for a pre muffler era Fox 35. They have 40th and 50th anniversary versions and didn't know what fits the older Fox. I bought one from them yrs back and think its the 40th with the additional strap they sell. Anyone know the scoop on this? The nice lady also told me to visit StuntHanger to get the info ;D
Thanks
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Bill,
Does your FOX 35 have bolt taps molded into the case? This makes a difference. If it has taps you need to add support tubes between the taps and the muffler base. This keeps the case from twisting and causing binding. If it has no tabs you need to have a strap that goes around the back of the case and contacts the case on the sides of the bypass. This is similar to the way the early Enya engines mounted their mufflers. I would avoid using a hose strap type of mount as it will squeeze the case and cause the piston/cylinder to bind.
Best, DennisT
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This is the early Fox 35 without the "ears" for screws. The one I have already has a "springy" wire strap that clamps just tight enough to hold the tongue muffler on. I think it uses the same muffler as the one with ears but uses a clamp instead of screws. Thanks.
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The one I have already has a "springy" wire strap that clamps just tight enough to hold the tongue muffler on
Sounds interesting. Could you post a picture?
Thanks!
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I went to take a pic and found this one actually has a solid u shape strap like Brodak sells. It has a little spring to it but not what I was thinking. I must of had a senior moment and confused it with a past engine! Yep I feel real stupid but it is what it is. Anyway, after comparing everything the Fox case with ears uses the same Big Art tongue (40th anniversary) muff as the older case without ears. The only difference is the early case uses a strap. I didn't try the strap on the case with ears but it looks like it would fit if you used longer screws through the ears (or around broken ones) and then into the muff.
Thanks.
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(https://stunthanger.com/smf/profile/?area=showposts;u=117)
Youll find a piture of Bob Giesekes set up , here :http://library.modelaviation.com/ma/1976/12/control-line-aerobatics
(http://"http://library.modelaviation.com/sites/default/files/css/css_xE-rWrJf-fncB6ztZfd2huxqgxu4WO-qwma6Xer30m4.css")
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Sounds to me that you have one of the older Fox .35 versions (without the muffler ears). No problem mounting a tongue muffler (Big Art or RSM both work fine). It appears that you have one of the manufactured cylinder straps so just install it one the back of the cylinder so the bends match up with the indents on the cylinder then run 4-40 x 1-1/4" socket head bolts through the strap and screw them into the tongue muffler. Just tighten things up until the muffler will not move on the exhaust port. Do not over tighten as the Fox has a very thin crankcase and you DO NOT want to distort it.
For those who do not have a manufactured strap just use a piece of 1/16 x 1/4 brass (K&S). Wrap it around the back of the engine to get the curve then bend each end to create the ear pieces. Drill a 1/8" hole in the ear piece. You've got a muffler strap.
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Been flying a Big Art tongue muff with home made k&s strap on McCoy 40 RH several yrs. Worked fine but it came loose last week and got lost in the grass. Looking back, I kind of like the steel strap better, it seems to hold a little tension on the screws like a lock washer and stays tight with light torque.
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If you like to make stuff, and can get hold of some of that steel strapping material that they use for banding stuff to pallets, you can make a pretty good strap out of that stuff. You can cut it with good tin snips, and you can form and shape the ends a bit for some strength, Punches are handy for making the holes but drills will work on this material.
Type at you later,
Dan McEntee
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I would be mighty tempted to hack a bracket out of 3/8" aluminum plate and fit it over the bypass area with just a wee bit of clearance...then nest it onto the engine with some JB Weld. If the engine has been run and not prepared for epoxy adhesion, I'm pretty sure the JB Weld would only stick to the bracket, but a bit of heat would make it pop off, regardless.
RSM's tongue muffler is almost certainly the lightest you'll find anywhere, and ***the price is right***. LL~ Steve
PS: I'm not a fan of tongue mufflers...or Fox .35 Stunts, for that matter.
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When you add a muffler on the FOX 35 you need to watch the temp. On mine I needed to reduce the prop from a 10x6 to 9 1/2 x6. Depending on the ambient temp/humidity the load of the bigger prop and muffler can cause pre-ignition. You will hear a crackling in the engine note. On real hot days I have gone down to a 9x6 and actually had lap time go down cause the engine was running smoother. Others have gone to a colder plug or added head gaskets, but for me the prop change was simplest.
Best, DennisT