What fuel for .049

I seem to recall that Cox Glow Power was 10-15% nitro, and their racing fuel
was 30%? Anyone remember? I was at a hobby store today, and all they had was
20% fuel, labeled "for cars". Can I run that in an teedee 049? I don't need
max power, but I do need it to run good and reliably.
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Cox fuel was 25% Castor, 25% Nitromethane and 50% Methanol. Refer to other blends under :Fuel facts & FAQ + Fuel Tank installations: on my webpage and also refer to the main COX enthusiasts web page and download manuals Cox engine - "How to Get Best Performance" Cox manual. .pdf Cox engines
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or email me for some other Cox manuals not listed on that site.
Regards Alan T. Alan's Hobby Model & RC Web Links
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Be really careful with RC car fuel. Cox engines were designed to run on fuel with castor oil. Too many RC fuels today have low oil content and most of that synthetic. Cox engines use a ball and socket joint where the piston and connecting rod come together and just a few runs of synthetic oil fuels can ruin one. Sig sells castor based fuel and the 1/2A fuel sold by Tower has enough castor to work (but maybe not enough to keep your engine for years). Remember that Cox engines are out of production so parts are an issue. You might look at current production engines like the Brodak Mk I or Mk II. The Mk I made by CS and is a sport motor. The Mk II is made in Moldavia (sp?) and is a high performance motor. For what you can get selling a Cox engine on ebay you are well on your way to paying for a $49 Mk I or a $59 Mk II. Do a google search on Brodak they are one of the biggest suppliers of Control Line items in the US. Bob Furr
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.Bob Furr
Fox still makes a .35 for a reasonable price, though I'm not sure how long they will be around. I've heard nothing bad about Brodak, I've heard good about OS. I've thought a bit about this, and maybe it's time to leave the past behind? These old Cox engines are going for an arm and a leg on eBay right now. I have a teedee .049, a teedee .051, and 3 "sure start" cox .049 engines, all brand new. I just picked up an os .35, and if it's no good I'll take a chunk of my tax return and bite the bullet and buy a new one. Those old Cox engines may have been good, but they weren't *that* good. I'm not a collector - I want something that works, and Cox is gone and as you and others have said the prices on parts is going to go through the roof.
Did Brodak buy out Fox, or old Fox stock? I notice they are selling a lot of Fox engines on their website.
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Nope Fox is alive and well and still making engines in Fort Smith. The engines are really a sideline anymore as they are a full line machine shop and have manufacturing contracts for other products. They do offer a great discount if you have ANY old engine to trade. They will give you 50% off list on any of their glow engines. That makes their great Fox 25 or 40 about $60 which is more than competive with OS or Thunder Tiger. Just put that worn out old motor (any make or size) in the mail to them along with a check or your credit card number. Bob Furr
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I used to run .049s and .051s on 40% nitromethane, 20% oil fuel, and the oil was 2/3 Klotz, 1/3 castor. The engines had their own peculiar ways- the cylinder and pistons never wore out as long as you reset the ball-in-socket joint occasionally, the older production cranks had a too-thin web, and these would eventually break at high rpm. This was corrected around 1972 or so when Dale Kirn pointed out the weakness to Cox. Later cranks are heavier in the web. -Paul
Zootal wrote:
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Paul Ryan
You have the nitro percentages correct - 15% for the regular fuel, 30% for the racing fuel, and as far as I know the oil was 22% castor.
15% nitro is fine for .049's but you should consider it a minimum level for decent running habits (not for smaller though - 25% for .010's and .020's) . 10% "runs" in Cox .049's according to some people, but in my honest opinion it totally sucks and I've run a lot of these engines in my lifetime so far. They love 25-30% and burn that with about the same level of stress as a .40 on 10% so don't let the relatively high percentage sway your opinion. The oil content should be minimum 20% and a good percentage of that castor. If you cannot find a can of "1/2A fuel", Sig Champion 15% - 25% in the 20% oil variety is a very good choice. As bare minimum, and I say this with reservation, use 18% oil minimum, but this should be at least 50% castor. Many LHS's carry bottles of SIG castor oil, so if you can't fnd something decent off the shelf, buy some 15% or better yet 25% nitro fuel with 18% oil that uses a syn/cas blend, then add about 4 ounces of the castor to a gallon jug. Or proportionally less for smaller jugs.
Avoid car fuels like the plague. They often run ridiculously low oil percentages and high to all synthetic. You'll beat the crap out of that poor TD .049 with those fuels. The advice regarding the ball and socket small end joint and it's need for mucho lubrications is good advice.
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