Ok so i used to have this control line trainer plane long ago. Well, the plane is now gone and all I have left is this little .049 cox engine (the kind without the built-in fuel tank). So, I figure I should put it to good use and either rig it up to my Accipiter Badius plane, or, attatch it to my Nitro Evader.

Here is my question, I know the motor calls for 15-25% nitro and at least 18% castor oil. Back then, this synthetic stuff wasn't around. I am wondering if my Traxxax 20% top fuel that I use for my nitro stadium truck will work on this engine? It still needs to be broken in too.. so will the fuel be ok?

Also, how long do these engines last? I was told they practically last forever. Thx.

Your little Cox has a steel cylinder with an iron piston, and a plain bearing crank. It will wear out in a hurry if you run it on synthetic oil. At least 20% castor is requijred. Using the right oil, it will truly last almost forever. Nitro at 25% is OK, I run that in mine. Your car fuel probably wont do - not enough (if any) castor oil.

The break in is almost immediate, run one or two tanks of fuel at a slightly rich setting and it's ready to go in anything you want.

Bill.

Hi!
Don't agree with you Bill ! modern synthetic oils work fine in all COX engines.
I have run a COX Black Widow for many years on 15% all synthetic oil and 15-25% nitro and it just love it.

Regards!
Jan K
Sweden

[b]Jan:

I thought you might come in here on that. There have been too many documented problems with the iron piston and steel sleeves running all synthetic to let your comment go. The varnish build up on the piston is an essential part of the sealing, with synthetic this seal will never be achieved.

And the plain bearing crank, with the bearing material being the crank case itself. Even K&B had to change the case on the Sportster 65 befause of people like you. The original design was fine when using castor oil, but people running synthetic oil were having crank bearing failures. In the later production K&B cast a bronze bearing into the case, using synthetic oils the bronze held up better. But better yet with castor oil.

Bill.

I agree with Bill. The Cox will be much happier and last much longer on castor. I'll bet that if you post this question on the 1/2a forum you will find still more castor proponents.

jess

Jan...
Count how many post you wrote about syntetics oil... sure more than other folk in RCU...

I agree with Bill

Jens Eirik

jan, please remember that the black widow has an anodized case that holds up much better as a bearing material than the bare aluminium of the product engines. running synthetic in them, including motul micro, results in a very sloppy crank in no time.




dave

Actually, most accounts I've read say that castor is needed to properly lube the ball socket at higher temps. Since Cox brand fuel uses castor, I do too. Perhaps a blend would be best...the castor for the ball socket, the synthetic to prevent (or slow) varnish buildup.

George

Jan...
Count how many post you wrote about syntetics oil... sure more than other folk in RCU...

I agree with Bill

Jens Eirik

[/quote]

Jens, as you may recall, Jan sells a certain synthetic. Perhaps that would account for a degree of bias

jess

Jess

He sell the synt. oil but the oil can not use in all modelengines, some engines need castoroil.

Interest to learn out how many modelengines are damaged/worned out after Jan recommented the synt. oil as replace for castoroil in new and old engines with other material than common modelengines with modern material such as ABC and ball bearing.

Better to care the engine and follow instruction about fuel with castoroil or synt.oil recommented by modelengine factory and modelengineer or the warranty will be void in case the engine are damaged or worn out in short period cause wrong oil.

Jens Eirik

Good point Jens. A iron/steel piston cylinder setup with lots of hours on it will sometimes get some of its compression from baked on castor on the piston. Apparently since most synthetics run so clean they will remove this varnish buildup and leave you with significantly lower compression. Duke Fox used to advertise that his Fox Superfuel (5% nitro, 29% castor) would put new life in an old engine (pre ABC era). If you have an old iron/steel with low compression, running 25% or so of all-castor fuel may improve performance.

Cox .049's run a bit hot and using all castor will usually necessitate cleaning varnish of the cylinder walls. This was often done with a gun cleaning solution containing nitro benzene. A wet brillo pad worked too.

I'm sure many already know this stuff, but some may not.

George