I knew a while back that Cox produced several types of cylinders for the reed valve .049 over the years and 2 or three different types of crankshafts (the beefier ones for the Cox cars) and even 2 or 3 case variations (the early conical nose and the later straight nose) BUT WHAT ABOUT PISTONS? I thought all Cox .049 pistons were created equal. Imagine my surprise when I disassembled a .049 reedie Baja Buggy engine (the one with the worm gear and pull start) only to find that the piston first had a beefier connecting rod which was quite thicker at the crankshaft end and tapered down as you go up toward the piston (all my other Cox connecting rods are of uniform thickness) and while it has the usual ball and socket connection it's different from the usual piston which has the socket "shrunk" around the ball of the connecting rod in that the socket is secured in the underside of the piston with a tiny circlip and looks like it's removable!

yes it is removable but not very easily the couple that i have are also fitted with a beefier looking rod but they're aluminium not steel.

more info in a thread from long ago, http://www.rcuniverse.com/forum/m_76.../tm.htm#762848



dave

Zagnut, yes, you're right, the con-rod does appear to be aluminum versus steel. And you're also right in that it would probably be hard to remove since the circlip looks essentially like a miniature piston ring and doesn't seem to have any way to grab it to compress it.

Zagnut, I looked at the thread and the picture you posted and YUP that's the piston/rod I was talking about.

meowy,

Yup just when you think you have seen it all you will come across something weird Cox wise. Have you ever seen the brass cylinders and aluminum piston combo?

Later,
Tim

I have a Space Hopper I bought about 1961. It had a three piece piston with a circlip. The rod end fit was pretty loose so I took a piston out of my Cox parts stash and swapped it out. Runs very nice. Need to put it on an airplane.

Jim

Tim, interesting, nope, never seen one like that. You mean brass instead of leadsteelalloy thing? Any easy way to tell them apart?

I still have the one, but have never used it for flying because of it's age ( it still has a copper new look inside though ), and the aluminum rod is a concern . Is it somthing worth the "risk" of using for sport flying?


Remby