Fuel For A Fox .35 ABC

I have acquired a Fox Stunt .35 ABC from a forum member, and wonder what fuel mixture it needs? I was told a while back by someone who has one, that the Fox still needs a lot of oil even if it is an ABC. How about the old standard mixture with 29% castor?

Treat your ABC Fox 35 as if it were a standard Fox 35. Especially when it comes to fuel.

ABC Fox 35s require 22% lube with 11% castor and 11% synthetic. I have 5 of these engines and that is what makes them sing. I use 5 or 10% nitro depending on the run time that I need.

You can survive with a little less oil. 25 % is as low as I would go, but you can go with a little more synthetic and less castor. One thing you need to remember is that Castor oil doesn't burn nor flash off as easily as the synthetic and so carries out a lot of heat. Since the old Fox is not noted for an excessive amount of cooling fin area, you need all the cooling you can get.

Bigiron

Bigiron,

Lack of cooling area is what I was told is the reason for using a lot of oil in these engines, even if they are ABC.

Be careful on this. The Fox 35 has a meehanite iron piston and steel sleeve. This requires a lot of oil. Experts, such as GMA recommend 28% all castor oil for the Fox 35S. The newer ABC piston/sleeves for the Fox 35 means that a lesser castor oil/synthetic mix is OK.

Anytime you have a lapped piston/sleeve such as Torp, McCoy, Fox, you need lots of castor. Otherwise, these motors will not last long. Castor oil tends to build up varnish, but this can be elimated by taking the motor apart and using very fine steel wool on the cylinder.
'Tis a pain, but that's life!

I would agree with Marvin's 25% oil. On an ABC, some synthetic is desirable to keep the deposits from forming. Powermaster 10/22 mixed half and half with 5/29 is what I've run for several years without any problems.

I run 10%Nitro, 12%Castor, 12%Klotz in my ABC Fox 35. This is the same blend I start with when running OS plain bearing ABN type engines.

Fred

I ran 22% 50 50 castor syn, in my ABC for about 3 gallons and the wrist pin bosses in the piston became worn pretty bad. There just is not much thickness in the piston and the aluminum just will not hold up like cast iron. My 2 cents.

I've been competing with that engine and fuel combination since 1996. I've had zero problems. Crist Rigotti and Alan Hahn have both observed the engine's performance over the 8 years. Perhaps they will comment.

I believe the piston in Fox's ABC setup is made from a fairly hard aluminum/silicon alloy. I'm surprised it would wear fast with 24% oil.

Fred

>I've been competing with that engine and fuel combination
>since 1996. I've had zero problems. Crist Rigotti and Alan
>Hahn have both observed the engine's performance over the 8
>years. Perhaps they will comment.
>
>I believe the piston in Fox's ABC setup is made from a
>fairly hard aluminum/silicon alloy. I'm surprised it would
>wear fast with 24% oil.
>
>Fred

Over the last several years I have watched Fred fly his Mustang with the Fox in it and I agree it does perform very well under a variety of weather condidtions. Good engine.