bogateer

In my neverending quest for spare parts I was perusing the Airfield2000 site and found that the cylinder/piston combos for the Babe Bees, TDs, and Texacos all have different part numbers. What is the difference between them? Along the same lines...how does the Texaco differ from the other Cox engines? Does anyone know where I can just get the pistons without having to buy the cylinders (and are the pistons different amongst the different engines?)? Last...why is the top of the piston coated with what appears to be copper?

Thanks,

Rob

Jim Thomerson

The pistons are copper coated and then finish ground on the sides, then nitrated for hardness. The copper keeps the top and the underneath from being nitrated. If there are differences among the pistons, I am not aware of them. The cylinders are not hardened and wear faster than the pistons. I think you are better off to get sets, as any individual cylinder you have may be well worn.

The Babe Bee cylinder has a single bypass port and the TD has two with some extra fluting. Don't know what a Texaco looks like.

lukesp

Rob,

I have been told in the past that the pistons were copper plated, case hardened and then ground to final size. The copper was to prevent the case hardening from reaching the piston top (which would make it too brittle and cause cracking) and the inside of the piston, which should also remain soft. Presumably the pistons are made from free turning mild steel or leaded steel. That way the case hardening is where it should be, on the wear surface of the piston. It makes sense because case hardening only goes skin deep, 1/64th's of an inch at the most. The cylinders are (again, presumably) made from free turning mild or leaded steel, untreated.

How true this is I don't know, it sounds good though. If anyone here has worked for Cox then I am sure they could confirm this, or dismiss it as BS.

Luke.

edit: Cross post with Jim.

rainedave

My Feedback: (1)

I posted this in another thread, but since we're talking pistons I think it's ok to show these pics again.

The one on the left has much thinner walls (although the picture doesn't show it too well) and the top is different. I have no idea what it came out of. The one on the right is from a brand new SS. You can clearly see the copper.

iglowhead

My Feedback: (192)

The Cox Texaco was designed for Texaco 1/2a free flight events where the right power/fuel economy combination can be the difference between winning and loosing. This design runs at a lower RPM (9100-9600) turning a 7-3.5 prop with duration of run time from one 8cc tank of fuel being about 5 minutes. It has the high velocity .062 venturi plastic backplate (with fill nipple), red anodized long tank (without fuel fill and overflow nipples), a black anodized case. It also has a free flowing reed holder (not the wire retainer). Some were issued with the tall five fin head some were not. It has the cylinder with the twin narrow slot exhaust ports.
Tom

"if it ain't scary, it ain't powerful enough"

ffkiwi

Not surprising that TD, Babe Bee and Texaco cylinders have different part numbers because they are all different. For that matter Cox actually produced about 10-12 (the experts disagree) different variations on the 049/051 cylinder theme. Obviously TD's-regardless of age are fully ported-two tranfers flutes and and open exhausts. Babe Bees were originally one transfer flute but two open exhaust ports (ditto Golden Bees) -both had subpiston induction.Latterly Babe Bees had the slit type exhausts. QZ's had twin transfers open exhausts, but no SPI-coz they were intended for silenced use from the word go. I don't know what the Dragonfly used-probably the QZ type since it had a muffler/throttle as std.Texacos as has already been stated are/were intended for max economy slogging on 8x4 props at around 7000 rpm and 7x3-1/2 at ca. 9,000-hence exhaust porting restricted and a heatsink head to cope with the heat load. The pistons were pretty much interchangable until the Killer Bee came on the scene with the lighter piston. (which still ought to be capable of retrofitting to earlier types) TD's and KBs supposedly had a tapered bore as well. Then there were the variations with ground external barrels to take exhaust throttles, plus a couple of weirdo mesh types used in cars-which I suspect were full depth exhaust ports, and probably preceded the twin slit type
The copper plating was simply applied to keep the piston crown soft enough to be peened around the little end to form the cup for the ball, while the remainder of the piston was hardened. I can think of no especial reason for the top of the piston to be plated-unless there was some thought that this rendered it less likely to carbon or varnish up....