I have acquired a fox .35 with a hemi-head, stuffer back plate and an ABC piston and liner. My question is what i should use for fuel? Thank you    Nick

Terrence is right if you live in the States, if not having fuel shipped over the boarder can be a pain so I use Omega 10% with 12 oz. of castor added.

I use any fuel that has a castor/synthetic blend around 22%.   Get mine from Arizona,  Mark Smith alias Excaliber Fuels.  I think he is in Phoenix area and attends VSC each year.

Unfortunately, an ABC plain bearing engine is sort of an enigma, because the piston/cylinder works very well on eighteen to twenty percent synthetic, but that plain bearing likes closer to twenty percent lube, and probably some Castor.

I'm sure no expert, but I would use lots of oil to protect the plain bearing, but with synthetic to keep down the carbon build up. Since the crank runs cooler than the rest of the engine, I'd probably err on the side of too much Castor at say ten percent, and the rest synthetic to bring the total to twenty, or twenty-two percent lube.

Hopefully, someone who really knows what they are talking about will either agree, or argue with my theory (since I don't own any plain bearing, ABC engines). 

Bill

I have acquired a fox .35 with a hemi-head, stuffer back plate and an ABC piston and liner. My question is what i should use for fuel? Thank you    Nick

Hi Lester
Below is a copy of my fuel article pinned at the top of this forum, I would suggest you read the whole things, however short answer is if I was you I would use a 25% total oil fuel with 1/2 castor 1/2 synth. This will keep the ABC part happy and not gum it up but will have plenty of oil for the small bushing in the case and the unbushed AL. rod.


I would like to tell you there is one Stunt fuel formula to run in all motors, I said I would like to tell you that…unfortunately this is not the case, and will never be as long as we have such a wide range of motors and running styles.  What I will tell you is a good formula for the most common types of engines.  Make sure you pick a fuel supplier who will give you consistent fuel day to day ,and will blend fuel for your motor needs or has fuel to match your needs.  Stay away from any supplier who will not tell you the oil percentage, or who say one type works for all motors. I see this  much to  often also, It is unfortunate, but a lot of fuel manufactures will try to fool you about the oil and nitro percentage. One trick is to measure the oil by weight and all other ingredients by volume. Doing so, they can claim that the fuel is  for example 18 % oil , when in reality it is only 14.9 % oil content. Using weight one for 1 ingredient and volume on the others does not  equal 100 % . Other things are changing oil types, going to cheaper Nitro’s, and adding in other types of Nitro parrafins.

   So what percentage do you try? For motors like Fox .35s, OS Max 35s or the old McCoy’s and K&B’s, use a fuel with 26 to 28% oil content; preferably half castor and half synthetic, up to 75% castor  is OK. These  motors have very small bearing surfaces, and are subject to much wear and heat, most are all plain bushing motors and most have unbushed rods. They need a lot of  oil  to help cool the engines. Since these motors run hot, they need  extra oil to keep them lubed,clean, and to carry out heat . If you have one of these that is  in very good  shape but, is  just starting to get some brown or black varnish plating on it, the synthetic mix will clean it  up for you, resulting in increased life.  Do not use the synthetic  blend in an old motor that has a lot of time on it with all castor fuels; the synthetic will remove the castor varnish off the piston and sleeve and will in some cases, leave you with the worn-out motor that had to start with.  Also always try to NOT use  prop shaft extensions with these engine, as it adds a  lot of  wear on the crankshaft bearing.

Randy