old but interesting Cox fuel oil debate

fredvon4 on Tue Feb 18, 2020 7:54 am

I got the link from

http://controlline.org.uk/phpBB2/viewtopic.php?t=15513&highlight=

https://www.rcgroups.com/forums/showthread.php?1325147-Cox-oil-testing-findings

Bernie has a few very interesting posts page 3 or 4

balogh on Tue Feb 18, 2020 11:08 am

Thanks Fred, very interesting read indeed...especially where Bernie chimed in and commented about the Estes and pre-Estes tolerances of the COX cylinder/piston combo.

@ Bernie, if you read this, I am wondering if finally you have managed to find a manufacturer for the 049 TD cylinder/piston sets with the pre-Estes OEM tolerances? I understand the TD cylinder/piston combos you sell are still the modifications of the double-slit exhaust Surestart cylinders?

The posts about the castor and synt oil experiments on COX engines is also very interesting. Even though the blackened piston top in a COX engine may suggest to some that the engine is misused at high temperature, in fact I always thought the high temperature of the piston top is the key to forming the protective varnish in the ball-joint cup.

My oldest TD051 with the black piston top had its balljoint set only once in its near 300 (!) hours of dependable run it performed in my RC Toucans.

old but interesting Cox fuel oil debate Blowby11

fredvon4 on Tue Feb 18, 2020 12:02 pm

I have severely abused TeeDee 049/051 on nose of combat planes with up to 50% Nitro and almost always oil with more castor than synth ...later on Ken Cooks writings I shifted to more synt ratio and less total oil %....down to 20~22%....over RPM breakage were always crank pin or shaft....neve poked a rod through piston top....never bent a rod......I don't think I have ever owned a cox 6x3 prop.....

most interesting screw up....launched at something way over 20K rpm and motor quit in three laps.....get plane...motor and piston ok...no cylinder or head to be found....finger tight I guess.....

I strongly disagree with OP that resetting is not needed and the slop is not a problem.....he seems to believe (despite his blown pistons) that rod end gap and hammering in use is not the cause for the wear....funny considering his pedigree.....I used wrong fuel oil mix in one of the outboard engines he is engineer on Low end Force 15 HP (generic Mercruiser) and shattered a piston way out on the lake.....grrrrrrr

balogh on Tue Feb 18, 2020 12:16 pm

Haha Fred I also lost one fingertight cylinder and head mid-air years ago.. Very Happy

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old but interesting Cox fuel oil debate

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