Unusual Cox 049 cylinder - Need help identifying

EDIT: sorry Bernie.. I see what you mean by the "boss" between the exh. ports and the fins..   Mine have that boss by the looks of my photos..

double-post

It doesn’t seem to have the flat cuts for the wrench on the top fin either

I have at least one double-slit exhaust cylinder without the wrench cuts, but I didn’t notice any other difference when I looked at it. Will see if I can find it.

The lack of the wrench flats made me think it’s some kind of an interim product, first batch of double slits or something. Afterwards they found that the flats are now needed, since the wrench won’t fit the new exhaust ports.

Now that I think about it, in my opinion, the ”boss” above the exhaust, would have been a better place for the wrench flats, than the very thin top fin.

KariFS wrote:Now that I think about it, in my opinion, the ”boss” above the exhaust, would have been a better place for the wrench flats, than the very thin top fin.

The larger diameter at the upper most fin area provides the greatest torque advantage, making it easier to wrench with a stamped sheet metal wrench.

What Kari says also makes sense IMHO except for cases when a muffler is added. Stock COX mufflers extend up to the lowest fin and hence would cover the wrench flats if cut into the "boss" as we call it in this thread.

For the wrench cuts made by COX  the top fin was thicker than on old stock e.g. thin wall cyliners with no stock cuts. I filed wrench cuts on several old stock thin wall cylinders where the top fin thickness was no different from the rest, and it still holds well i.e. not bent by the wrench...truth be told, I always apply some silicone laden oil like WD 40 on the cylinder base thread before engine reassembly so that castor will not be caked there, and cylinder removal is easy, the torque applied on the wrench not destroying the top fin area near the wrench cuts.

GallopingGhostler wrote:

KariFS wrote:Now that I think about it, in my opinion, the ”boss” above the exhaust, would have been a better place for the wrench flats, than the very thin top fin.

The larger diameter at the upper most fin area provides the greatest torque advantage, making it easier to wrench with a stamped sheet metal wrench.

True, but if the flats were on the thick bottom fin, one could fit a ”proper” wrench too, if desired, since there would not be other fins on the way.

But as Andras said, this would not work with the muffler.

I personally have messed up at least one cylinder and a wrench, trying to force the glowhead without applying heat. Oh well, that was 40 years ago, you live and learn

Always a good idea to oil the threads while assembling, this was not done at the factory, cost, time etc, but I too add some oil to all of the threads. I use the same oil that I use everywhere, i.e. air tool oil.

Edit. Found the one I was thinking about. Got it used with a bunch of other engines, no idea what kind of model (if any) it left the factory with. Dual slit cylinder without the wrench flats, but it does have the thick fin/boss after all. Bernie may have found something special



Edit 2. Found a genuine thick wall Tee Dee 051 cylinder with the same profile as Bernie’s mystery cylinder. The rest of my thick wall Tee Dees have the more usual arrangement.

Thanks Kari and to all others that have posted, but all those cylinders have that thicker lip or ring above the exhaust port; whereas the one I posted does not, it has a regular cooling fin instead.

Bernie, looks like you have a rare one. I think Roddie is right, probably an early short-lived production before further changes were made. Used up the stock, every engine sold is a profit.

Love the pristene condition and like new finish on the Babe Bee.

Interestingly, between the 3 lower cooling fins the diameter is necked down to thin cylinder levels.

Kari mentions of damaging the cylinder exterior by wrenching 40 years ago. Yes, I have ruined maybe a half dozen thin cylinders engines 10 years prior to Kari, a Pee Wee and Babe Bees, some product engines. The thin cylinders were easy to ruin without other precautions when inserting the Cox wrench into the exhaust port.

I still have a few thin cylinders, but those I ruined sport later piston cylinder sets.

GallopingGhostler wrote:Bernie, looks like you have a rare one. I think Roddie is right, probably an early short-lived production before further changes were made. Used up the stock, every engine sold is a profit.

Love the pristene condition and like new finish on the Babe Bee.

Interestingly, between the 3 lower cooling fins the diameter is necked down to thin cylinder levels.

It's actually a picture from someone on eBay asking if we had even seen such a cylinder, as is on his un-run Babe Bee. Since our answer was "no", I posted here and also advised that person that he could follow the thread on the forum himself.

No problem, Bernie, my bad. It is interesting, the trivial nuggets and advice / suggestions brought up by you, Matt, Jacob, András, Kari, Roddie, and all the rest in this forum. It seems we have a final compendium of Cox engine history and then a new exception appears.

There is never a dull moment in CEF.

The more I think about this, the more it looks like a production mistake. Given the millions of cylinders produced, they probably had special tools for their lathes, so that all the fins and other shapes were done on the top part of the cylinder on one go (as opposed to feeding a thin tool into each fin gap). Think of a "comb" shaped tool.

Pick up and install the old tool, and you'll get a cylinder like this. I have one that is probably from the same batch, it's a thick wall Tee Dee 051 cylinder, currently installed to my "051 KillerWannaBee" Never noticed it before this thread.



This cylinder was pulled from a Tee Dee that I converted to a non-SPI cylinder and a muffler. Also a Medallion carb... The idea was to make an engine that would be easier to start than a Tee Dee, could be used with a muffler, but would give more rpm than a Medallion with a muffler. Like most of my engines, it has never been tested. Given the possible "rarity" or oddity of the cylinder, I might re-assemble the engine back into its original form. I have a bunch of other Tee Dees to play with, but then I would have to re-name the "Wanna Bee" to 049

You're right George, never a dull moment

I checked the three slit cylinders I have and all have the boss above the exhaust….Whoever had the Bee with the unusual cylinder must have cared for it as it looks like its been polished a bit…. Maybe at least there’s some hints of its age by the other parts of the engine….

KariFS wrote:Given the possible "rarity" or oddity of the cylinder, I might re-assemble the engine back into its original form. I have a bunch of other Tee Dees to play with, but then I would have to re-name the "Wanna Bee" to 049

Before you do that, with the name "The Wanna Bee", you may have a possible winner for the Cox Engine of the Month Contest!

GallopingGhostler wrote:No problem, Bernie, my bad. It is interesting, the trivial nuggets and advice / suggestions brought up by you, Matt, Jacob, András, Kari, Roddie, and all the rest in this forum. It seems we have a final compendium of Cox engine history and then a new exception appears.

There is never a dull moment in CEF.

I posted a reply digging into the top fin not being milled for a wrench, and how Cox (poorly) suggested how to remove them...then deleted it about 2 minutes after posting it as I realized what Bernie really meant.

I do recall reading that at one point Cox used two milling machines for their cylinder production, their old setup that made the thin wall and later the stepped cylinders, and the new setup that made the later thick wall cylinders.

I went and looked at a couple of the interim screened exhaust port engines, and they all looked like this cylinder, without having double slits.  My speculation is that your engine, is an early double slit exhaust port engine.  According to the Cox Handbook, the screens started showing up in 1976 and the dual slit showed up in 1978.  I am going to guess that at some point they decided to save money and stopped milling that portion of the cylinder, either after prototyping it or sometime later in the process.  This was probably to save money or because they had some other manufacturing issue. Just my guess. It's an interesting cylinder.