Fox 36x Engine

The squeak is only there when I turn it with the screw driver. I cannot get my finger in there to turn it. There is no noise generated when the crank is turned.

I gotta say, I really like the way the offset/crooked plug looks in these. Break away from symmetry! Viva La Revolution!

I do want this engine to last. I have big plans for it. Got a plane that will be here Thursday. Really excited!

RR

If I understand correctly, and it makes sense to me, that for engines with ball or roller bearings, you need some synthetic oil in the mix. It's a lot slipperier than castor. I would oil that bearing with some after run oil or something light and see if the squeak stops and it turns more freely. I use 10W Singer sewing machine oil in mine for ARO. Many people use ATF. That's pretty slick stuff.

I took it back apart and fiddled with it a bit. The noise stopped. I can turn it with my finger jammed in there but it is stiff. It may be from the low run time it has. It probably was run a couple times and then stored for some years. I am going to do some extensive running with it tomorrow. Gonna see how consistent it can be.

Did I mention it came with the original box, instructions, and an Enya nva? It also has the original venturi insert to allow it to run on suction.

RR

Okay. If the bearing is not completely free moving, I would highly recommend lubricating it with some light oil before cranking. Whatever you decide. Let us know how it runs.

Rolla, there were a few different versions of this engine. One thing that would help is a picture. Is the engine a ball raced engine or a needle bearing version? One thing to keep in mind with a Fox, the piston liner can go in anyway it's inserted and unless it's indexed, your not going to put it back in the same exact spot. This engine is not designed to run a prop larger than 9". My suggestion would be a 9x6 MA. You could even use a 9x7 trimmed to a 8.5 or a wide bladed 8x6 Taipan if you can find one. A common prop that was used was the Tornado white props. These older props however are more than likely destined for the trash can. IT WILL THROW A BLADE if you use a older nylon prop. This engine is iron piston steel liner and prefers at least 20% oil content. Due to the unavailability of parts, I would highly suggest castor and very little synthetics. As for nitro, I would use no more than 15%. It's not worth risking breaking the crank. The engine has the capability of doing 100mph and slightly above if tuned correctly. Larry Scarinzi was monumental in the design of that engine with Duke Fox. He was legendary with the Super Satan and Fox Blast fuel which was I believe 50% nitro. Larry made several engines based on the 36 design knows as the LS tuned Fox's. I spoke to Larry last weekend trying to bend his ear a bit. Larry is a funny guy and he's getting up there in age.

If the engine feels rough, it may be due to congealed castor in the balls. Run it, let it cool down and try again. When put away, the engine should be followed by a liberal dosing of oil like transmission fluid and turned over. This keeps the balls well lubed and cleaned. Back in the day pacifier tanks were used. These are pretty much a thing of the past and bladder tubing is used. No restrictor in the venturi. A medium wall tube should be used. I would say that your run is going to far superior using the bladder. This is a powerful engine. I would use caution if you never ran something like this. Let the person know who's holding the plane as well. If that plane surges you don't need the starting man to have the plane in his chest if it pulls forward on startup. Ken

The instructions say it has needle bearings. The model it will be going in needs a metal tank so that restrictor will have to stay for some time. I ran it with 25% Castor, 10% Nitro. This will eventually switch over to 29% Castor, 5% Nitro. I also remember to scratch a guide mark into the liner. I got it in nice and straight. I will upload a picture when I get home today.

RR

About to go run it again.

RR

Rolla, I certainly wouldn't use the 29% high castor oil. This could have a negative affect rather than positve. For one, the engine was designed for performance. You won't achieve that with that much oil. The other is that the metallurgy of engines from that period were sub par compared to a modern engine. The high percentage castor made up for the shortcomings of engine manufacturers. The .36X is a ball raced engine so it therefore wouldn't need all that oil. Having that much oil in the fuel could certainly take out the plug element due to over compression with all that oil. This has happened with several of my Fox combat specials. This engine although combat orientated, isn't like a combat special. These engines like a lot of prime to typically start. They will pop, backfire and run backwards. Something to watch as this can start a quick unwanted fire if not careful. This is especially true if your running crank pressure and the case gets flooded. The engine if working fine on your 25% is already more than enough oil for that engine. Ken

The problem with getting the 25% is cost. Sig only ships it in gallons with a large hazmat fee. To overcome this fee and make it cost worthy to buy fuel I would have to spend $90. I simply cannot afford this. I am also almost out of fuel. We lucked out and got our current gallon at the Muncie Hobby Shop which has since closed doors. Powermaster also makes a good CL brew, but they only do gallons. My LHS is not the best at re-selling fuels. They tend to hike it up pretty good. The 29% is my only other option. Unless I mix my own. But then I would have zero nitro.

RR

PS-It is weird how you say they typically take a lot of prime. Mine starts with almost none. Just get fuel to the venturi. Two flips and it is running. I do believe my nva needs cleaned. It was a bit extreme in its settings changes.

Rolla,

I wonder if GMA 10/22 would work ok? It's made by Powermaster and usually available locally. If any of your LH Shops stock Powermaster they will be able to get it. Less than $20 a gallon here in OK.

Ken recommended it for the plain old Fox .35, but I am not sure about the .36X

Guess what the GMA stands for?

Ron

Is it the guys name? George M. Aldrich. I do not know his middle name. I sent them an email asking some things about their fuel. Gonna see what they say.

RR

Piccies!!









Ugh. Engine leaked oil on the carpet. Gonna have to get that cleaned up!

I use Powermaster GMA in every older engine I own with the exceptions of Mccoy's. I never had a failure nor am aware of anyone who has. Others will tell you not to use the fuel, I say do as you desire. The first thing someone will tell you is that the synthetics are harmful to the castor varnish and it will break down what's left and make your engine useless. I say show me. I've been running GMA in all of my Fox.35's for the past 12 years full out as lean as they will run. The 36x is no different in terms of metallurgy as a "Stunt" .35. The Difference is in the power. These engines have the capability to run 100 mph plus with work done to them.

Keep in mind one thing, you can do more damage on a lean run using a tank than using a bladder. Just something to consider. Bladder keeps the fuel load consistent and the case cool due to the constant supply of fuel. As the bladder depletes, it leans towards mid flight and then richens to the end . A tank is going to keep leaning continuously. The .36x can break the crankshaft right at the opening is pushed too hard. This is generally the case if you use high nitro. One thing to keep an eye on is the case itself directly where the needles bearing are located. You want to make sure the needles don't seize or the crank is possibly rotating on the needles rather than with them. The case usually tells all as it will show discolorations on the exterior of the case.

These are my experiences with this fuel and I'm not suggesting you have to buy it. I'm just saying that your 25% castor fuel if working in that engine is fine to use. The engine will initially benefit from it. If your not accustomed on how to set the needle with these engines, it will also safeguard you in terms of added protection. Many times, these have to be launched quite rich. The engine has a ferocious appetite for air and fuel due to the large venturi. If running on bladder, you may even need to pinch the bladder prior to launch.

The other thing, the Enya needle valve is probably larger than the stock Fox. THis will rob some power but will reduce the choke area more than likely making the engine run on suction better than the stock Fox spraybar. These engines don't care too much for tanks. They will work, but they take some experimenting. They work far superior without restrictor and bladder. WHo knows, try it and it may just work fine. I've seen stranger things work. Ken

What is the oil percentage that you use? Is it their 23% mix?

11/22 which is 50/50 half synthetic half castor 22% total oil

I can only say try what you have. Keep one thing in mind with these old engines. They can be problematic at times. Even self destructive. Just something to always remember. For the most part they're durable but even the kindest care can result in a failure. Your example looks like it's been well taken care of. Finding parts is sometimes easier just to purchase a entire engine as the part availability has dried up with these. I see occasional cranks offered but very few rods or piston/liners.Ken

Hmmm, I thought it was 10/22 my mistake Rolla. I am about to pick some up myself.

Ron

I used to love powermaster in my O.S. Engines, 22% was perfect. Its been a couple years, but wasn't GMA fuel all caster, at 25 or 29%

Mark,

The GMA fuels come in a variety of flavors. The do have a GMA with 25 and 29% all castor like you remembered.

Ron

Being a diesel guy I have always worked with tons of castor. My PAW 15 uses 33% oil. I have always felt weird using synthetics. I mostly worry about over lean runs. With heavy castor it is not real serious. With high synthetics it could destroy it. I can tune fine but sometimes maidens go awry with fuel tank issues or weird engine quirks.

The kit for this engine is coming in tomorrow. It will be my first full fuse and wood combat model. It will also be my first combat model out of 1/2a.

If done right then I could see synthetics being great. But I do not always do it right. So, I am going to stick with castor for now.

RR

What kit did you buy? Or did you already mention it?

I just remembered! My first flights with my Skyray 35 it had a Fox 35 Two-Speed. It was missing the upper needle set but it is not necessary to run at all. We did not have any pure castor fuel so we used Sig 15% Nitro 20% Oil. Half Castor Half Synthetic. Most flights were rich as I was very light weight at the time and my feet would slide on the ground when it picked up speed. We had one lean run where the tubing got crushed between the tank and the back of the engine. It ran for several minutes at peak. It landed and I was shaking all over. I was really worried it would pull me over! The engine was fine though. No loss of compression. Ended up quite hot.

Someone had told me the Sig stuff would work and that 15% Nitro was the top amount for a Fox 35. I was also told that the Fox 35 need extra oil to aid with cooling due to the light construction it has.

Powermaster offers to blend fuel. I am gonna think up several batches to ask them about when they reply back. Including some 1/2a versions.

The kit I purchased was the Super Combat Streak. He offered to cut the Manx Cat but he did not know if he would be able to stand at the machine long enough due to some pain (He had an infection of the skin). He had the Streak kit cut so I went for it instead to avoid undue pain. I will have to order a BH-557 tank from Brodak for it. The 36x will go straight on it.

Kit: http://www.builtrightflyright.com/New_Web_Pgs/kits/CombatStreak/CombatStreak.htm

Tank: http://brodak.com/a-t-f-wide-wedge-uniflow-fuel-tank-3oz.html

This will also be my first uniflow tank

RR

The Combat Streak should be a blast! You may want to rethink the tank size. A stock .35 will use 3.5oz to do the pattern and Ken mentioned the 36X is thirsty. Of course if you only sport fly then it will probably be OK.

Ron