buffumjr

As to increasing the stroke, I recently made a .36X con rod from scratch. I had wanted to include a bronze bushing in the lower end. No room for that. The .36X case does not have room for ANY increase of the stroke, unless there is a radical decrease in the crank pin size. That would not have been smart. There is only a hundredth or so clearance of the crankshaft to the lower case. They HAD to make the case a little bigger to accommodate that. I'm betting they used a modified .36X casting plug.

Oh, how I yearned for that when I was a kid! Ads said, "40xBB".

I now own a .40 BB R/C Schnuerle. I have yet to mount it to a plane. It's probably a lot stronger, but it's NOT the same.

earlwb

Fox was continuously changing and or improving the 36X engines. It would not be a surprise if there was a slightly larger crankcase that was used when he made the .40 engines. I can't tell anything about the 36X lineage as Fox had made numerous changes over the years to the engines. One of the MECOA people like Bill Mohrbach might kinow the answer though. He pretty much has one of every example Fox engine made, but maybe not every .36x engine variation made though.

buffumjr

One matter of concern is that Fox seems to be in trouble. The last time I talked to them, they were temporarily shut down "until the economy improved a bit". Scary stuff.

1QwkSport2.5r

It's been like that for a long time. Several years. They had some spare parts for some engines a few years back, but I'm sure their stock dried up quickly.

earlwb

They have a bunch of contracts to make things other than model engines. Some were government contracts too. With all the wars winding down, I assume some of those ended. But they were really getting into making parts for other companies though. Years ago when I visited the factory they were super busy making sockets for Sears Craftsman tools. I remember them making parachute rings for some government contract years ago too. They were making firearms parts as well. Even Winchester, Remington and the others outsource parts to be made for them. The bread and butter money making stuff is not with model engines but everything else. So the model engines was mainly a side business to everything else. Model engines was sort of a gap filler between the other jobs to keep the employees busy.

http://www.foxqualityaero.com

hsukaria

When I visited the Fox factory about 4 years ago, they were making parachute rings for the military. Neat stuff. They had huge boxes of rough castings for mufflers and carbs piled high. But those parts needed machining to be usable. I did not see any castings for other parts though. At the time they were trying to develop small gassers like the .50, .74, etc... But I never saw much come out of it.

Sport_Pilot

Even when they were selling engines they may not actually manufacture engines for a long time. They are mostly in business for contracted machine work.

earlwb

They actually staggered the engine production runs apart. They would plan for when they wanted to make a particular engine. Then for example, they would make 100 .60 engines. But it might be three to six months later then they would make 100 .35 engines, or later 100 .45 engines and so on. They don't just make all of the engines at one time. Thus over a period of a few years they would make all of the engines at different time intervals. Other model engine companies all do the same thing too. The actual numbers or quantities for a particular engine would vary too. It depended on what the market was doing and wanting and how may orders they had too.

Cougar429

My Feedback: (3)

One of those carb pics finally jogged some brain cells so I pulled out the box of spares.

Here is what I found. The two-needle carb I know. That other one looks like the newest version, but I'm wondering if someone modded it before I grabbed it and threw it in with the others. Seems to be missing pieces, such as a way to adjust HS.

Not sure what they were for and would have to dig out the other 60, (one mounted is sporting a Perry pump an carb). Bore size on both is 0.330".

1QwkSport2.5r

Looks like the one on the left is setup for a remote needle and has an airbleed. EZ-Just carb? The newest Fox carb is a two-needle design without airbleed. Carb on the right with fuel line attached looks like an MkX based on the main needle and holder.

Cougar429

My Feedback: (3)

Would either of these work with a pump? Asking as the dedicated Perry carb is a pain to adjust correctly.

1QwkSport2.5r

I don't know, maybe... I tried a Perry pump on a TT Pro .46/stock carb and it would load up horribly below WOT no matter how I adjusted the regulator. I think the real world answer is probably a demand regulator like a Cline or Iron Bay. Or if you can cut a Walbro carb apart that has the pump and regulator on the same side. Backplate or muffler pressure to tank, checkvalve to hold tank pressure and the regulator does the rest. Something I plan to try when I can afford a regulator.

Cougar429

My Feedback: (3)

The setup is in a G/P F-15 which is notoriously nose heavy. Moved the Rx and battery to the tail and fit the tank near the CofG, quite a ways back from the engine.

1QwkSport2.5r

I'd use the stock carb and get a cline regulator.

Lou Crane

Has anyone tried a muffler-tap tank pressurization, with a "too-large" tap hole?

Such a tap supposedly, long ago, reduced the tank-pumping pressure by allowing back-flow. That 1) obstructed flow to the tank as reverse flow opposed part of it, and 2) self-leveled average pressure to the tank at a lower value..

I've never dabbled with tests on these, and assume MANY, MANY details will arise...

1QwkSport2.5r

I should have asked, but you're moving the fuel tank and other components (and using a pump) only for balancing purposes, correct?

JPMacG

My Feedback: (2)

I have a Fox 74 with a stripped rear muffler thread. Any suggestions on how to repair it would be greatly appreciated. I worry that if I drill and tap for a larger thread I will risk breaking thru the cylinder wall

spaceworm

I am sure the stripped hole was SAE thread. Pick the closest next larger metric thread and rethread the hole with that metric tap. Worked for me. Good luck

Sincerely, Richard

hsukaria

I did something similar with another engine, but it was metric and I re-tapped it to the next bigger SAE size.

JPMacG

My Feedback: (2)

I think the original tap was 6-32. I'll go to the next larger size, either metric or 8-32. But I need to drill a bit deeper than the original hole. I want to have more threads, and also, I need some room for the tip of the tap.

It looks to me like if I drill deeper I will break out into the cooling fins, not into the cylinder. Can anyone confirm this?

spaceworm

[QUOTE=JPMacG;12081057]... I need some room for the tip of the tap. ...
QUOTE]

Start with a regular tap and finish with a PLUG tap that will thread almost to the bottom of the hole. Good luck

Sincerely, Richard

kamakazi

My Feedback: (1)

I drilled my fox .74 hole out and put a short threaded screw with nut and thread locker. works ok

the pope

Poor fox,that's gotta hurt ! Cheers the pope

JPMacG

My Feedback: (2)

I don't have a bottom tap, but this may be the excuse to get some.

Hobbsy

My Feedback: (102)

JP, you can easily make one by grinding the point off of one. Although that requires that you have two.
Farmer Dave