BOB MOORE

I recently got an Fox 1.20 twin from a buddys family( He Had Passaway) This engine is from the 70's. It has an C&H ignition . My question should I use more or less oil in this engine. I have run this engine and it really turns up. The fuel I have is for my Zenoah 23 and is 23% oil . I have used this fuel mixture for about 20 years BOB MOORE AMA 6559

Jezmo

Bob, it is my understanding that this is a bushed connecting rod engine. If I am correct then 16:1 is the lowest I would go on the oil ratio. I am running my ST51 glow on gasoline/spark ignition and anything less than that on oil and the rod starts suffering. If it's a needle bearing rod then you can go out to 40 or 50:1 without trouble as long as you use a modern high quality oil such as Pennzoil Air Cooled two stroke (The only dino oil I would personally use) or one of the high quality synthetics such as Redline two cycle racing, Motul 800, BelRay, etc.

Charley

My Feedback: (2)

Just out of curiosity, how do you know the rod starts suffering?

CR

Charley

My Feedback: (2)

Wow! That's a lot of oil. Or is 23% a typo?

CR

BOB MOORE

That should have read 23to one ratio > My old fingers sometimes to not follow what my brain means to say. BOB MOORE
And thanks for the reply .

Jezmo

Hi Charley,

I took it apart about every fifteen minutes of running and looked at the pin and bushing during the first 3 or 4 hours after conversion. After that initial run-time I have removed it and disassembled it about every 2 or 3 hrs of run time. During it's last ten hours or so I have only had it apart once but I have a good feel now for how much oil it needs to keep from eating itself. I spun one bushing trying to go 22:1 on the ratio (that didn't take long) and the max time I have put on it so far without breaking it is 30 hrs. I guess the short answer is "open it up and look at the rod to see of it is suffering".

BOB MOORE

Thanks for the info, I will keep a close check on the engine as I use it. A lot of people have trouble with Fox engines , but I have had good luck in past. I had a Fox .15 and a .45 that I ran for years. They worked good for me until they wore out. BOB

Jezmo

I know this does not apply to all Fox engines (certainly not the ringed ones) but most were designed for and needed an all castor oil based fuel. I ran Foxes for many years and had very good success with them. I still have some in my collection and they were all run on castor fuels. They are still usable engines however I don't run them any more and they are more reminders of all the years of fun I've had flying both control line and R/C. It's been a very good 45 years. I hope your twin treats you well. Good luck and happy flying.