Cox 049 parts source?

I am trying to make my Cox Baby Bee .049 run really, really good for the Scientific/Walt Musciano event. From a secret source, I have heard that you may need to use a shim between the base of the cylinder and the crankcase to adjust the timing/height of piston. Shushh.... don't tell anyone. But, I need to obtain some of these cylider shims to do this. Where can I get the shims? It is not a stock part so Cox doesn't sell them. I have tried a couple of other sources and no luck so far. Burnis doesn't have them. Suggestions?Nick Vanmatre

LAST EDITED ON Dec-02-04 AT 02:35 PM (CST)
 
raising th cylinder will lower the compression ratio..not good...there is one thing you could do that would increase the performance regarding timing...but it takes a skilled hand and a sharp "burr-knife" to do it...also use a newer glowhead like the one thats used on the olympics...that glowhead should give u a noticeable increase in rpms...jim

What you are looking for is a Cox 09 head gasket. I'll check and see if I have one to spare. It may or may not help. One variable on Cox engines is the height of the part of the crankcase where the cylinder screws in. So, for a given engine, a shim may help, whereas for another it will do nothing, or hurt. This is also, in part, why some Cox engines need more head gaskets.

Jim,
I would appreciate the 09 head gasket, if you find it. Btw, I tried to email you and the ssw system say you don't exist. Well...it says you don't have a working email address. You might want to check your profile and see if there is an error. Thank you for the offer.
Nick Vanmatre

shimming the base of the cylinder is done to align the transfer ports to the crankcase. the exhaust ports should face fore and aft (parallel to the axis of the crankshaft). i lap the spigot on the case (the part of the case that the base of the cylinder seals against) to get the xfer ports aligned. use some 1000 grit emery cloth laid on a piece of glass and lightly lap the spigot in a figure eight pattern and check the fit every so often. when the ports are in the correct orientation, switch over to a whetstone (well oiled) to finish it off to a nice smooth finish. light pressure is the key. and patience. lots and lots of patience. a heavy hand will gouge the aluminium and introduce all sorts of air leak potentials. Precision Brand Products offers a neat hole punch device for making shims if you'd rather go that route...... www.precisionbrand.com it's called "tru-punch". it makes shim fabrication a pure joy, much the same way as the "drill doctor" makes drill bit sharpening enjoyable.

Sorry I have to disagree with you on the purpose of the cylinder shims Scooter. I bought several of the shim kits from Joe Klause when he was still in business and they came with instructions for use of the shims. Their purpose was to adjust the sub piston induction on the liners, he gave a set dimension that you were looking for so using the shim holder and assorted shims you adjusted until you reached this figure, which if memory serves me correctly was .010 gap. I also used the shims to align the ports as you suggested and unfortunately I found no performance gain from aligning the ports or setting the sub piston induction. So basicaly the shim set's were a waste of money.

For what its worth, my best-running Black Widow happens to have its exhaust ports facing front & back. Not my doing; just the luck of the draw. Is that why it runs better than the others? I dunno.
If you want your Babe Bee to run better, put a BW double-bypass cylinder on it. Oops, probably illegal. Never mind.
--Ray

I agree with minnesotamodeler, if you want your .049 to haul put a TeeDee piston and liner on it. Just be warned that once you start getting over the 20 - 21 k range these engines can be finicky. They're lot's of fun to play with but sometimes you just don't know what makes them go, you can build 4 engines exactly the same and swear that they feel identical and have a differance in rpm from 18k all the way to 22k, and if your going mouse racing you want to be over 20k and to be really competitive you want to be at 22k.

>I agree with minnesotamodeler, if you want your .049 to haul
>put a TeeDee piston and liner on it. Just be warned that
>once you start getting over the 20 - 21 k range these
>engines can be finicky. They're lot's of fun to play with
>but sometimes you just don't know what makes them go, you
>can build 4 engines exactly the same and swear that they
>feel identical and have a differance in rpm from 18k all the
>way to 22k, and if your going mouse racing you want to be
>over 20k and to be really competitive you want to be at 22k.

Yup, they're pretty erratic. I have three BWs; I swapped parts around and improved all three!! I guess their production tolerances are a little suspect. Buy a Norvel; it's cheaper.
--Ray

Ron,

I had a slightly different experience with the Klause shims. Instructions were to shim to get the piston top at TDC just level with the top of the land where the plug gaskets seat.

That, per instructions, set intended sleeve port timing. And, yes, of course there was considerable sub-piston porting...

I live at just about 5000' above sea level. That's not really 1/2A country. Talk about finicky when you've got so much air in your air down near sea level?

Anyhoo, carefully set up, used in small stunters - not top end racer or combat models - the KK shims seemed to help noticeably.

There is/was a combat guy (around LA?) who took over quite a bit of Joe's performance stuff when Joe retired.

If you really feel you need these shims check out ebay.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=19164&item=5939954608&rd=1

When you start racing the Cox reed just go ahead and pull all your hair out.

Don't bother with the shims they don't really do anything. The main thing that will make a Cox go fast is a good piston fit which very few of them have.

Some bolt on tricks that do work are the cut down 1702 plug, the K-tech reed and the DD crank with fully bushed case. Don't know if these are legal for your event.

>When you start racing the Cox reed just go ahead and pull
>all your hair out.
>
>Don't bother with the shims they don't really do anything.
>The main thing that will make a Cox go fast is a good piston
>fit which very few of them have.
>
>Some bolt on tricks that do work are the cut down 1702 plug,
>the K-tech reed and the DD crank with fully bushed case.
>Don't know if these are legal for your event.
>
>
>Giffy

Has anyone tried boring out the venturi tube and running pressure?
--Ray

i tried unsuccessfully to run a reed valve using a binky pacifier some years ago. it wasn't in a plane but rather in one of the cox dragsters, the funny car. my dad came up with the idea..all it did was braaap a time or two. we both got frustrated (he more so than i...i was probably about ten at the time) and gave up on it.

about the orientation of the xfer ports.......i was told that the transfer ports oriented in the rotational plane of the crankpin benefited from the slight boost that the spinning crankpin produces at that particular region. maybe i'll butcher up an old BW by installing draft taps at various points and determine the velocity of the charge. that sounds like a good saturday afternoon-wind blowing-raining-no yard work-no painting-my wife is calling me a "goober" type of project.

I've run a Cox Killer Bee on pressure. No real problem with it - just use a low pressure 1/2-A bladder (5/64 i.d. x 1/32 wall latex tube). Nice thing is you can unclip the bladder line, then just use the spring starter, and it starts right up.

>I've run a Cox Killer Bee on pressure. No real problem with
>it - just use a low pressure 1/2-A bladder (5/64 i.d. x 1/32
>wall latex tube). Nice thing is you can unclip the bladder
>line, then just use the spring starter, and it starts right
>up.

I think you missed my point: I have 2 BWs set up for pressure now, yes, they run on pressure no problem. My question is concerning venturi diameter: I have drilled the backplates out to the diameter of the venturi tubes, but have not tried drilling out the tubes themselves. I was just wondering if anyone else had tried opening up the venturi--I don't want to risk destroying one of my own engines experimenting with it.
--Ray

That was actually in response to "Scooterjay".

Nick:

Here are a couple of generic Cox engine tricks.

First, be sure to use the high performance glow heads, with the marks around the top.

Second, be sure the reed is right. Distortion or age can really change performance. Try a couple different ones and see if it helps.
Also, the mylar reeds will be consistant and should give close to optimum performance. Make sure ALL the surfaces are absolutely clean on the reed and the tank/spraybar setup.

Third, be sure the top of the rod (ball end) is properly set in the piston. There is a tool for that. Excessive looseness hurts performance and can be fatal to the engine if it lets go.

Fourth, the bolts that hold the tanks on just love to loosen up, affecting performance and leaking fuel. Check them very, very often.

Fifth, The tips of the needle valves love to break off in the backplate, spraybar setup. Also, crud can accumulate there. They may still run but not as well or consistantly. Be sure it is fully open and that the needle tip is smoothly shaped. They also sometimes leak air around the threads. A piece of silicone fuel line carefully fitted over the needle at the tank will cure that and help with needle wander.

Sixth, like the man said above, if you have several try methodically switching parts for the best combination. Like him, I used to do that and sometimes improve both engines. At least on the older ones, switching pistons to different sleeves sometimes did good (or bad) things. No harm in trying if done carefully. Strange thing, later on you might try it again with the same engines and improve them again.
Make sense? probably not, but these little beasts always have had a mind of their own.

No science here....just that us old duffers spent a lot of time wrestling with those silver cased jewels as kids. We may not have known "why", but we did usually figure out "how"!

Good luck,

i told him right off the glowhead will make the biggest difference....but you may not be allowed to use it if its an era thing...jim

Strictly speaking, shimming the Cox cylinder is not allowed in the Musciano Meet. "Only stock parts (as delivered on the engine at the time) are allowed, no hop up or high compression heads."

I read "stock parts" to mean no shims as far as Cox is concerned. Fox, however, shimmed some of its 1/2As at the factory.

The guys that really have good running, legal Coxes simply were patient, trying a bunch of different ones, mixing and matching parts, and so forth. And this especially is true of OK Cub .049s. I have seen a (precious) few that really were strong. The Philly guys, by the way, campaigned a Sky Fury K & B that was quite fast.

Actually, the only event that requires ultimate rpm is the Speed event. You don't really need it for Stunt, although the more capable planes indeed have better than average running motors on them. And Team Race is 90% pit work.

Also, re Cox ports, this time the two port variety (illegal for Musciano), I don't think it matters whether they are fore and aft, of course holding deck ht at a constant.

Aha.. so no Norvel or Galbreath heads either..

All the comments I've made pertain to setting the engine up for class I mouse race where there are no restrictions to what you can do to the engine other than it can't have an exhaust extension and the the tank must be integral. (no drilling a hole and plumbing in a larger external tank) There is quite a bit you can do for performance and most of it is in fitting the parts carefuly. You can drill out the venturi tube to .080 for a definate increase in rpm, you can turn down the outside of the venturi tube and remove metal from the inner surface of the backplate to extend your range, (you need at least 35 laps per tank) and then with the addition of the Tee Dee cylinder and piston plus the Tee Dee glow head you "might" have a competitive engine after an inordinate amount of fitting and fiddling. Oh and I forgot we would run from 40% to 65% nitro with 20% oil and we would use five of the copper head gaskets for a nice steady run without blowing plugs. Some engines you could get down to four gaskets but usually the engine would'nt run steady and life of the plug was like a turn at the roulette wheel. The prop of choice around here was the 5x4 black grish tornado cut down to about 4 3/4 or 4 7/8 dia.

Thanks to all for advice. I didn't know that the shims wouldn't be legal for the Musciano event, which is my primary target. I am still going to go ahead and get those shims off of ebay, since they are hard to find. I figure I can use the shims, and the advice, to try and get the best performance I can. I am also playing with the Killer Bees just to hop them us, so anything would go. Of course, easy running is a goal also. Again, you all provided lots of good help. Thanks to all.
Nick Vanmatre

Nick,
Send your crankshaft and piston to Tim Wiltse to have the piston lightened and the crankshaft balanced, cound also send your crankcase to have it anodized at the same time,for hardness,after setting your deck height as stated in an above post by sanding/machining the case to get the fore/aft setting of the ports and getting the piston to just break the top of the cylinder bore at the head gasket surface and preping the case/crankshaft as outlined by Larry Renger in an old thread here at Stuka Stunt.
I asked the question here on Stuka Stunt of the placement of the exhaust ports and was told that the fore/aft setting was thought to be best because the crankshaft would actully help throw the fuel charge into the intake ports. I don't know, but have been setting up all my Cox engines this way since and have had good luck.
I use the Teflon reed and after break-in, have seen an RPM increase over the copper or Mylar reeds. I get the Teflon reeds,cylinder timing shims, and balanced crankshafts from Davis Deisel,all heads and glo-plugs from Larry Driskill at "Kitting it together",and head shims are from Cox.
If you research old threads on Cox engines here, you can build a killer Cox engine from the advise of people that have spent a lot of time with trail and error. I spent over an hour on the phone with Tim(in Corona)Gallegos just talking the importance of deck height. Contact me by E-mail and I will give you his contact information.
Didn't know it at the time, but ran into the Grand Master of the Cox engine Dale Kirn and his son at a local Hobby Shop when I lived in Ca.,helped me with Prop slections. May be able to dig up his phone number as well.

Good Luck,

If you go out to the whittier narrows model site there is a good chance you'll run into Dale if there is a contest going on. Dale is a wealth of information and super approachable here is the link yo his website http://kirn.hypermart.net/

Shimming heads is not a problem for the Musciano Meet. Sometimes, head shimming is the difference between the engine running or not running, much less performance.

Joe Klaus's old company has the head shims. The name changed (I think) when he sold it. I can't think of the name (Custom Craftsmanship, or something) but will look it up. It might be on garf's jumbo CL website.

Curell

>Shimming heads is not a problem for the Musciano Meet.
>Sometimes, head shimming is the difference between the
>engine running or not running, much less performance.
>
>Joe Klaus's old company has the head shims. The name changed
>(I think) when he sold it. I can't think of the name (Custom
>Craftsmanship, or something) but will look it up. It might
>be on garf's jumbo CL website.
>
>Curell

I think the shims mentioned (at least originally) are those at the base of the cylinder, to adjust the height/port oreintation. One post suggested using an .09 head shim for this. Legal at Musciano? Maybe not.
--Ray

Ray: I may be wrong, but shimming a Cox cylinder doesn't seem to be within the Spirit Of The Rules, since they were not there in the first place. Using various numbers of head gaskets is allowed, since the engines involved here come with at least one from the factory.

>Ray: I may be wrong, but shimming a Cox cylinder doesn't
>seem to be within the Spirit Of The Rules, since they were
>not there in the first place. Using various numbers of head
>gaskets is allowed, since the engines involved here come
>with at least one from the factory.
>
>Currell

Yup, sounds right.
--Ray

I ran into Dale at Witter Narrows. He was setting up a ARF Nobler with his son. Two hours later, He was behind me in line at a local hobby shop while I was buying props. Helped me with prop selection and told me about the Kinghts of the Round Circle. Had I known who he was at the time, I would have been pumping him for Cox tips!! What a missed opportunity.

I looked, have no such thing in all my cox parts stash, not even in ny davis diesel drawer.
Am not going to use any of my engines or parts anymore, if anyone needs.
roger

The Orbiting Eagles club in Omaha has an annual class for middle school kids in the spring on building and flying CL models. We use coroplast flying wings and Cox engines. If any of you are no longer using the Cox engines and have engines or parts to give away we will take them. I spend a few weeks in March tearing down and rebuilding Cox engines to keep the costs down for the kids in the program.
Thanks in advance.

Bob Furr
15872 Farnam Street
Omaha NE 68118