Yes. The tank it too wide for the amount of fuel draw you have, or at least you will have a big change in the setting from beginning to end. I would suggest a narrower tank, or a narrower inboard tank.

    Brett

Inboard tank (in case you didn't know) means put the tank opposite the engine.  That way centrifugal force will tent to fling fuel toward the engine, rather than away.

Not only does the fuel get to the engine easier, but it makes for some self-regulation of speed, because the faster you go the richer the engine gets, which slows you down.

Best of all, you'll be able to run a 4- or 5-ounce tank, which (I'm pretty sure) you'll need if you want to fly the full pattern with that Fox.

              Chris, I'm not knit picking but I do see some little issues. Absolutely make sure your gear wire isn't touching the tank. It will chew right through the tank or sacrifice the solder joint on the end cap. It's a good practice to shim the rear of the tank out approx 1/8". This will prevent surging at the end of the flight and created a nice clean cut not to mention provide adequate fuel draw in the event the plane is not flying tangent to the circle due to yawing. In this case it will also get your tank off of the gear wire.  In addition, the single strap can loosen allowing the tank to pivot fore and aft. This isn't a big deal initially, but it can over time and vibration loosen up. if it tilts it will change the tank height even though the tank isn't theoretically moving up and down. I prefer to glue a piece of 1/8" ply on the front of the tank with epoxy. Why, in the event of a crash even one where you get caught and the bird gets a little flighty at the end the tank is susceptible to puncture. The screw on the back of the Fox's case cover will punch a hole right through the tank. The tank can slide forward and the ply is like a safety barrier. None of what I'm mentioning prevents a test flight.

           What prop is that? It appears to be a Master Airscrew. Master Airscrews work, unfortunately the newer GF series are very thin bladed for today's modern engines. Many fly your plane and combo with a 10x6, I for one don't care for the larger props and generally use a Master Airscrew 9.5x6, while it doesn't sound like much of a difference it delivers good drive and load for the Fox and not a overload. The 10x6 can over load the Fox on the Ring when your really trying to get the speed up and maneuvering. A 9x6 works well equally. However, the APC 10x5 can really tame a shaky Fox and offer good rpm's and workability. I contribute that to a harmonic balancer effect. The weight of the prop can take a shaky front end and place it in a rpm zone that doesn't cause it to shake so much. Every plane and engine is different so it's a good practice to try all of the above. I see the mention of uniflow tanks and my experience hasn't been good with using it on profile sport planes like your flying with a Fox .35. Vibrations can seriously compromise how the system works due to fuel foaming which is why we all were agreeing for you to support your tank better. All of this could be meaningful or it may not mean anything. This is all trial and error. I've found a squirt of Armor All in the fuel can be most beneficial as this can also stop foaming problems. The main concern here is that you have NO air leaks and your 100% certain you have the proper fuel delivery. At this point we can all assist you in working from there. While I know I might sound as if I'm going in all directions, there's so many little factors that can dictate how your engine runs. Vibration, fuel, prop, leaks, etc. 


   One thing you didn't show in your pic is the tubing over the needle valve fix I recommended. This is very critical. I would do that equally and test it out and get back to us and report your experience. Good luck, Ken