Cox Reed Valve FAQ
01-08-2006, 03:18 PM
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Cox Reed Valve FAQ
I'd like to start this thread as a FAQ to provide a single source of information on these engines, modifications and general care and use. This is a place for the old hands to put stuff that they think is helpful.
For the folks with questions this is the place to ask them. If you don't find it by the time you've read through the thread then it's high time that someone asked so ask away.
As much as possible I'd like to see this be longer and detailed posts about the various aspects but would also welcome the questions and answers to the common issues as long as they are not repeats. Hints and tricks also belong here. If some of you know of longer replies that were excellent by all means dig 'em up and quote them in here or provide links to the original thread along with a description of what the thread was about.
If you guys have questions or hints about how to run this thread please feel free. I'll remove the unrelated chatter later on but for now it can help to guide the thread. With luck I'd like to see this flesh out to about 4 to 5 pages of solid info and then grow slowly as the little things come up that we missed.
Hints on the type of material we need.
[ul][*] Engine type identification. Pictures are needed as well as a link to Martin Hepperle's excellent Cox resource. Cylinder variation guides, etc.[*] Care and feeding. How to disassemble, clean, care for and reassemble the engines along with tricks for the various special versions[*] Blueprinting or hopping up the engines. Conrod resetting, reed tricks, making new gaskets, polishing the crankcase rear seal, etc. [*] Starting and running hints, propeller options, Texaco'izing for non Texaco types, fuel choice, etc.[*] A guide to what sort of model size and performance expectations the Reedies can be used with. From 6oz racers to 30oz powered gliders.[*] Anything else Reedie Related that I missed.
[/ul]
As much as possible I encourage you guys to remember the fine stuff you wrote before and repost it either under your own name if you wrote it in the first place or as a quote attributed to the proper author. There's tons of fine stuff from the past that is often hard to find if you don't know the ideal search keywords to use. If and when you come across something then feel free to add it in and make this a great resource. I'd also welcome any new material and would ask that for some of the stuff that lots of pictures be taken to best illustrate the steps for those that have not worked much with the Cox products before.
Discuss away and don't be afraid of cluttering up the thread. I'll clean it up now and then to make it look spiffy and keep the older parts pared down to the meat and potatoes.
For the folks with questions this is the place to ask them. If you don't find it by the time you've read through the thread then it's high time that someone asked so ask away.
As much as possible I'd like to see this be longer and detailed posts about the various aspects but would also welcome the questions and answers to the common issues as long as they are not repeats. Hints and tricks also belong here. If some of you know of longer replies that were excellent by all means dig 'em up and quote them in here or provide links to the original thread along with a description of what the thread was about.
If you guys have questions or hints about how to run this thread please feel free. I'll remove the unrelated chatter later on but for now it can help to guide the thread. With luck I'd like to see this flesh out to about 4 to 5 pages of solid info and then grow slowly as the little things come up that we missed.
Hints on the type of material we need.
[ul][*] Engine type identification. Pictures are needed as well as a link to Martin Hepperle's excellent Cox resource. Cylinder variation guides, etc.[*] Care and feeding. How to disassemble, clean, care for and reassemble the engines along with tricks for the various special versions[*] Blueprinting or hopping up the engines. Conrod resetting, reed tricks, making new gaskets, polishing the crankcase rear seal, etc. [*] Starting and running hints, propeller options, Texaco'izing for non Texaco types, fuel choice, etc.[*] A guide to what sort of model size and performance expectations the Reedies can be used with. From 6oz racers to 30oz powered gliders.[*] Anything else Reedie Related that I missed.
[/ul]
As much as possible I encourage you guys to remember the fine stuff you wrote before and repost it either under your own name if you wrote it in the first place or as a quote attributed to the proper author. There's tons of fine stuff from the past that is often hard to find if you don't know the ideal search keywords to use. If and when you come across something then feel free to add it in and make this a great resource. I'd also welcome any new material and would ask that for some of the stuff that lots of pictures be taken to best illustrate the steps for those that have not worked much with the Cox products before.
Discuss away and don't be afraid of cluttering up the thread. I'll clean it up now and then to make it look spiffy and keep the older parts pared down to the meat and potatoes.
01-08-2006, 07:09 PM
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RE: Cox Reed Valve FAQ
I believe indoorff article fits here, so here is the link http://www.freewebs.com/doughtyhobbies/049tips.htm
Edit:
Hope we can make stikies out of these FAQ
Edit:
Hope we can make stikies out of these FAQ
01-08-2006, 10:46 PM
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RE: Cox Reed Valve FAQ
It is not my intention to be a wise guy, know it all or a guru. Questions have been raised and remarks made about Texaco - say what? It's time everybody got good at this. In my case it's 1/2 RC Texaco but it could be Free Flight and of course it need not be 1/2A at all. I love this event and the more guys that get with the program the better. Whether you fly competition or just sport fly for duration the same stuff applies.
S.A.M rules dictate what you may or may not use if you're going to compete in SAM events. Since I compete it these S.A.M. events, that good enough for me. Per S.A.M.:
"1/2 A Texaco engines must be Cox reed valve .049's with an integral fuel tank of not over 5.1 cc capacity. These must be basically "stock" engines as typified by the Texaco Jr., or Babe Bee designs. Other Cox reed valve engines such as the Black Widow, or Golden Bee designs are acceptable as long as the larger 8cc tanks are replaced by the 5.1 cc tank, such as found in Cox #1596 conversion kit, containing the smaller tank assembly. The only modifications allowed are: Moving the fuel pickup from the middle to the bottom of the tank, addition of a muffler, and/or addition of a needle valve extension."
This pretty much means no bladders, turbo chargers or CDI ignitions, just Cox stuff. You can put these engines together from bags or cans of parts but the Cox Texaco engine was a good starting point until the fuel capacity was changed (it used to be 8cc).
When I started playing with this event I purchased three new Cox Texaco engines. Two for runners and one for parts. In those days they cost $25.00 US each, this didn't break the bank at the time. They were really shiny and pretty - no junk. These were run/broken in with eight inch (8-4) props.
How were these engines different, I mean just because Cox anodized them a different color and called them Texaco's didn't mean anything, that was just petty marketing. As near as I can tell there is no difference in the crankcase. It was a straight taper type. Early Cox engines had a taper to the crank bearing, later engines had the reinforced straight section for our flush friends with electric starters. This means nothing if you use a starter spring. If you insist on grinding away at your crankcase with an electric starter the straight case would buy a little time before you trash the engine. You can use either type.
It was pretty clear that putting an eight-inch wood prop on would lower the RPM but not all that much. (Please note that 8-inch props come in different flavors, 8-3, 8-4, narrow and wide blade etc, you have to try some) It would load the engine down to about 9000-RPM but that's way to fast. Normal 1/2A fuel was too hot and sport RC fuel was too cold. I discovered the engines would run (kind of) on 10% nitro. I did alot of bench running just observing the engines during and after break in. It was apparent that I needed to retard the ignition if I wanted to swing these large heavy props. This is easy to do - drop the compression (which determines advance or retard). On a Cox reed valve this is done by adding or removing head gaskets. You get one with every glow head, save them you'll need them later.
Like all Cox reed valves these engines would come apart as they ran. Heads would come loose, tanks would come loose, cylinders would come loose, needle valves would unscrew etc. etc. In each case the engine would stop running long before the fuel ran out. I found I could glue these things together with silicon sealer/adhesive. This stuff would gum up the treads and stuff didn't come loose anymore. But, anytime I wanted I could still take stuff apart - pretty cool. Glue the head, cylinder and fuel tank to crankcase screws and pack the sealer into the screw head counter seats also.
Before I started using Silicon sealer, I noticed that every year I had to install a rebuild kit. I needed to do this because there is a small seal between the tank back and the tank that was leaking. This caused erratic engine runs. Replace the seal, the erratic runs stop and the engine runs consistently. Since the tank back no longer comes loose or rattles causing wear on this seal I've stopped tearing my hair out. This did bite me in the backside this year (4th year on the Model) - you decide. I changed it out.
Like all Cox reed valves, the engines were just as likely to start backwards as forwards unless I really spun the prop over to start it This is tough to do when it's mounted on a model. It didn't help that I removed the taper in the cylinder. I started using the ratchet spring starter; this allowed the engine to run in one direction only when it started. This was good but it was clear that the constant contact starter spring was robbing horsepower. I wanted that back. I now use a clip on (snap???) starter spring, not the constant contact ratchet type.
The cylinder had TWO intake ports like the Black Window - no SIP as near as I can tell. It was not a single port design like the Baby Bee. It used a rectangular type Mylar reed valve with the plastic gasket/retainer, this works well. The Tank was off the wall. It has a very small passage from the needle valve to the reed valve. This was smaller than the 5.1cc Baby Bee tank. This was where Cox did their throttling. I wouldn't worry about it, the Baby Bee tank with mylar reed valve works fine.
Cox used a five fin glow head on this engine, it looked cool but the three fin sport heads (the ones we're taking off of the Sure Starts) work just fine - save them. Why they put a five fin glow head on this engine I don't have a clue, somebody must have thought the engines would overheat. They don't. The real problem these engines have is they run cold and die. Retarding the ignition with head gaskets keeps them from overheating - so, you have to warm them back up. To do this I elected to go with the Cox muffler. This allows the engine to stay warm and it also throttles it down a bit. The really cool thing about the muffler is the engine purrs like a kitten. It turns the engine into a flying cartoon - excellent.
Since S.A.M. rules specify Cox reed valve engine, that's what we gotta use. The rules do not say whether it has to be new or worn out. I wear the piston and cylinder out with lapping compound - 800 mesh or finer. I want the piston to protrude from the cylinder about 1/16" with no noticeable drag. The downside is this lets the engine rev up, the upside is that when you lower the RPM with head gaskets you've recovered the lost fuel for the run. Every time the piston goes up and down you've just used up .049 chi of fuel mix, you might not have needed to do this if the model will fly with less RPM. The engine need not prop over in a snappy fashion; I'm using a starter spring to do that.
Reed valve needle valves are a traditional pain in the neck. They are too loose in the threaded needle valve seat and the springs don't hold them in place. At one time the firm (now gone) Kustom Kraftmanship offered a Texaco backplate with a needle valve extension. It also happened to have a collet-locking nut on it and fine threads. I got three Texaco units and one Black Widow backplate. These needles no longer turn in or out from engine vibration. It is unlikely that you can find one of these available now; you'll have to devise your own way of doing this. Silicon tubing and a washer is the first place I'd start. The fine thread is no big deal. Mine tank backs aren't for sale.
The fuel line Cox uses in the tanks is also an issue. It works ok for the first year, then you had to replace it. When they're new they work fine. After about a year they get stiff and they begin to straighten out drawing fuel from the center of the tank - not good. With the current price of rebuild kits, this gets expensive (did I mention I'm also a cheapskate). Use a piece of K&S aluminum tubing to make a new permanately curved fuel line that picks it's fuel from the back of the tank. KK used to sell these, toughen up and make your own. Your engine will now suck down all the fuel in the tank.
With my Texaco engines I have to fly the wing. Fortunately small old timers are pretty nice little wing flyers and gliders. If you're a 3D or SWR kind of guy you may not like this event - you can't fly to prop. This is a Radio Control venture; it's not a steerable freeflight. I once watched a guy latch a new model with his transmitter sitting on his table - the receiver was turned off. I've watched guys holding their transmitters launch their models - the receivers where turned off. A certain Moderator did this, we allowed the flight and he did take first with it. My personal starting drill is to turn the radio gear on, check the control surface functions and then proceed with starting the engine. If they are going to run they start right up, if they don't I stop and find out why.
I think the same issues exist with Cox Pee Wee's and the cure the same. A couple extra head gaskets and a seven inch prop - dreamy. I have an old Super Tiger 23 that I bought in Hong Kong back around '71. I finally began using it but noticed one very unpleasant aspect. It burned up a glow head with every engine run (usually 10%). I tried cold plugs but still no joy. I finally got mad (yea that always helps) an carved out a new 0.015" head gasket with some K&S stock and my trusty jewelers saw. The engine was over compressed with a single 0.015 gasket just right with two with 10% nitro. I had bugs in my teeth after that. I suspect that coming from Hong Kong, Super Tiger may have been thinking FAI fuel. The point of this tale is that there is nothing sacred about the compression ratio - feel free to change it. Cox engines made this easy to do and rember your milage may very.
Regards - Steve B.
Bruce feel free to edit this as you may see fit...
S.A.M rules dictate what you may or may not use if you're going to compete in SAM events. Since I compete it these S.A.M. events, that good enough for me. Per S.A.M.:
"1/2 A Texaco engines must be Cox reed valve .049's with an integral fuel tank of not over 5.1 cc capacity. These must be basically "stock" engines as typified by the Texaco Jr., or Babe Bee designs. Other Cox reed valve engines such as the Black Widow, or Golden Bee designs are acceptable as long as the larger 8cc tanks are replaced by the 5.1 cc tank, such as found in Cox #1596 conversion kit, containing the smaller tank assembly. The only modifications allowed are: Moving the fuel pickup from the middle to the bottom of the tank, addition of a muffler, and/or addition of a needle valve extension."
This pretty much means no bladders, turbo chargers or CDI ignitions, just Cox stuff. You can put these engines together from bags or cans of parts but the Cox Texaco engine was a good starting point until the fuel capacity was changed (it used to be 8cc).
When I started playing with this event I purchased three new Cox Texaco engines. Two for runners and one for parts. In those days they cost $25.00 US each, this didn't break the bank at the time. They were really shiny and pretty - no junk. These were run/broken in with eight inch (8-4) props.
How were these engines different, I mean just because Cox anodized them a different color and called them Texaco's didn't mean anything, that was just petty marketing. As near as I can tell there is no difference in the crankcase. It was a straight taper type. Early Cox engines had a taper to the crank bearing, later engines had the reinforced straight section for our flush friends with electric starters. This means nothing if you use a starter spring. If you insist on grinding away at your crankcase with an electric starter the straight case would buy a little time before you trash the engine. You can use either type.
It was pretty clear that putting an eight-inch wood prop on would lower the RPM but not all that much. (Please note that 8-inch props come in different flavors, 8-3, 8-4, narrow and wide blade etc, you have to try some) It would load the engine down to about 9000-RPM but that's way to fast. Normal 1/2A fuel was too hot and sport RC fuel was too cold. I discovered the engines would run (kind of) on 10% nitro. I did alot of bench running just observing the engines during and after break in. It was apparent that I needed to retard the ignition if I wanted to swing these large heavy props. This is easy to do - drop the compression (which determines advance or retard). On a Cox reed valve this is done by adding or removing head gaskets. You get one with every glow head, save them you'll need them later.
Like all Cox reed valves these engines would come apart as they ran. Heads would come loose, tanks would come loose, cylinders would come loose, needle valves would unscrew etc. etc. In each case the engine would stop running long before the fuel ran out. I found I could glue these things together with silicon sealer/adhesive. This stuff would gum up the treads and stuff didn't come loose anymore. But, anytime I wanted I could still take stuff apart - pretty cool. Glue the head, cylinder and fuel tank to crankcase screws and pack the sealer into the screw head counter seats also.
Before I started using Silicon sealer, I noticed that every year I had to install a rebuild kit. I needed to do this because there is a small seal between the tank back and the tank that was leaking. This caused erratic engine runs. Replace the seal, the erratic runs stop and the engine runs consistently. Since the tank back no longer comes loose or rattles causing wear on this seal I've stopped tearing my hair out. This did bite me in the backside this year (4th year on the Model) - you decide. I changed it out.
Like all Cox reed valves, the engines were just as likely to start backwards as forwards unless I really spun the prop over to start it This is tough to do when it's mounted on a model. It didn't help that I removed the taper in the cylinder. I started using the ratchet spring starter; this allowed the engine to run in one direction only when it started. This was good but it was clear that the constant contact starter spring was robbing horsepower. I wanted that back. I now use a clip on (snap???) starter spring, not the constant contact ratchet type.
The cylinder had TWO intake ports like the Black Window - no SIP as near as I can tell. It was not a single port design like the Baby Bee. It used a rectangular type Mylar reed valve with the plastic gasket/retainer, this works well. The Tank was off the wall. It has a very small passage from the needle valve to the reed valve. This was smaller than the 5.1cc Baby Bee tank. This was where Cox did their throttling. I wouldn't worry about it, the Baby Bee tank with mylar reed valve works fine.
Cox used a five fin glow head on this engine, it looked cool but the three fin sport heads (the ones we're taking off of the Sure Starts) work just fine - save them. Why they put a five fin glow head on this engine I don't have a clue, somebody must have thought the engines would overheat. They don't. The real problem these engines have is they run cold and die. Retarding the ignition with head gaskets keeps them from overheating - so, you have to warm them back up. To do this I elected to go with the Cox muffler. This allows the engine to stay warm and it also throttles it down a bit. The really cool thing about the muffler is the engine purrs like a kitten. It turns the engine into a flying cartoon - excellent.
Since S.A.M. rules specify Cox reed valve engine, that's what we gotta use. The rules do not say whether it has to be new or worn out. I wear the piston and cylinder out with lapping compound - 800 mesh or finer. I want the piston to protrude from the cylinder about 1/16" with no noticeable drag. The downside is this lets the engine rev up, the upside is that when you lower the RPM with head gaskets you've recovered the lost fuel for the run. Every time the piston goes up and down you've just used up .049 chi of fuel mix, you might not have needed to do this if the model will fly with less RPM. The engine need not prop over in a snappy fashion; I'm using a starter spring to do that.
Reed valve needle valves are a traditional pain in the neck. They are too loose in the threaded needle valve seat and the springs don't hold them in place. At one time the firm (now gone) Kustom Kraftmanship offered a Texaco backplate with a needle valve extension. It also happened to have a collet-locking nut on it and fine threads. I got three Texaco units and one Black Widow backplate. These needles no longer turn in or out from engine vibration. It is unlikely that you can find one of these available now; you'll have to devise your own way of doing this. Silicon tubing and a washer is the first place I'd start. The fine thread is no big deal. Mine tank backs aren't for sale.
The fuel line Cox uses in the tanks is also an issue. It works ok for the first year, then you had to replace it. When they're new they work fine. After about a year they get stiff and they begin to straighten out drawing fuel from the center of the tank - not good. With the current price of rebuild kits, this gets expensive (did I mention I'm also a cheapskate). Use a piece of K&S aluminum tubing to make a new permanately curved fuel line that picks it's fuel from the back of the tank. KK used to sell these, toughen up and make your own. Your engine will now suck down all the fuel in the tank.
With my Texaco engines I have to fly the wing. Fortunately small old timers are pretty nice little wing flyers and gliders. If you're a 3D or SWR kind of guy you may not like this event - you can't fly to prop. This is a Radio Control venture; it's not a steerable freeflight. I once watched a guy latch a new model with his transmitter sitting on his table - the receiver was turned off. I've watched guys holding their transmitters launch their models - the receivers where turned off. A certain Moderator did this, we allowed the flight and he did take first with it. My personal starting drill is to turn the radio gear on, check the control surface functions and then proceed with starting the engine. If they are going to run they start right up, if they don't I stop and find out why.
I think the same issues exist with Cox Pee Wee's and the cure the same. A couple extra head gaskets and a seven inch prop - dreamy. I have an old Super Tiger 23 that I bought in Hong Kong back around '71. I finally began using it but noticed one very unpleasant aspect. It burned up a glow head with every engine run (usually 10%). I tried cold plugs but still no joy. I finally got mad (yea that always helps) an carved out a new 0.015" head gasket with some K&S stock and my trusty jewelers saw. The engine was over compressed with a single 0.015 gasket just right with two with 10% nitro. I had bugs in my teeth after that. I suspect that coming from Hong Kong, Super Tiger may have been thinking FAI fuel. The point of this tale is that there is nothing sacred about the compression ratio - feel free to change it. Cox engines made this easy to do and rember your milage may very.
Regards - Steve B.
Bruce feel free to edit this as you may see fit...
01-09-2006, 10:27 AM
#6
RE: Cox Reed Valve FAQ
Steve,
Unless I missed it, you did not mention that the Texaco has a smallish intake to increase fuel draw at the lower RPMs. As to the five-fin head, some of the fellows in hotter climates may disagree with the Texaco not overheating.
My Texaco engine is a 'tweener. It has the plastic backplate and large metal tank. I believe they have since gone to a plastic tank.
For screws that keep working loose, you might try blue Lok-Tite. It lets you remove the screws easier than some other versions.
I'd like to try Texaco some day. Didn't know they went to the smaller tank.
George
Unless I missed it, you did not mention that the Texaco has a smallish intake to increase fuel draw at the lower RPMs. As to the five-fin head, some of the fellows in hotter climates may disagree with the Texaco not overheating.
My Texaco engine is a 'tweener. It has the plastic backplate and large metal tank. I believe they have since gone to a plastic tank.
For screws that keep working loose, you might try blue Lok-Tite. It lets you remove the screws easier than some other versions.
I'd like to try Texaco some day. Didn't know they went to the smaller tank.
George
01-09-2006, 09:41 PM
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RE: Cox Reed Valve FAQ
GCB: Many years ago I ran a shiny black and chrome chopped '49 Panhead up and down I-5. I know all about blue loctite and of course real Harley nectar: the Red flavor. I don't want to strip or break off tank screws or anything else. I use silicon adhesive/sealer.
Good question about the air intake. Back plates on the Cox reed valves come in a number of different flavors. The earliest were pot-metal with two vents, one on either side of the needle valve. I've never noticed any difference in these, but I've never looked either. Next came pot metal back plates that were made for their engines. Some have no vent at all; these were for the Golden Bees and Black Widows. Their tanks were vented and as a result the back plate didn't need vents. The intakes on these appear as large as 1/8" and some small as 3/32". I had two of these in my stash that are about 1/16". I don't know why this is. The next type of pot-metal back plates had a single tall vent and a short one at the surface. I can only guess these are a newer Baby Bee back plate.
Then, Cox started making their black plastic back plates. These are my favorite back plates because they are noticeably lighter than their pot metal counter parts. If you're trying to save some weight this is a good place to do it. I have specimens (junk in my parts box) from Black Widows (no vents), Baby Bee's and Texaco's. Again there are variations in the air intake openings from 1/8" or 3/32". The pot metal and plastic back plates have (relatively speaking) a course ill fitting needle valve that loves to screw in or out due to vibration when they are in the air.
The product backs plates are yet another type, very often have screens over the intake and vary often have a fine thread needle valve and seal (though not always). These are nice. The needle valve is easy to adjust and the seal locks them in place. They also have one other thing; they have a large air intake, and the closest thing to a venturi is the reduction at the needle valve seat, which is hard to see because of the screen and needle valve seat. Current sure starts (which do have the large air intake but have crappy needle valve and no seal) are the exception - sorry.
Is there any rhyme or reason for all of this (he asks rhetorically)? Not that I am aware of.
Having said all this the intake opening in the tank back isn't the venturi. The venturi is in the tank. It's the tapered tube that runs from its seat in the back plate to the reed valve opening.
If you are concerned about the air intake fit the tank against it and look at the actual venturi. It will be smaller than the air intake (except product engines) the venture in the tanks vary. The Black Widow starts out at about 3/32". The Baby Bee starts out about 3/32" and the Texaco starts out a bit smaller than 3/32". The exit port behind the reed valve varies also. So... if your going to using a Cox reed valve tank your stuck unless your very clever and paitent. You could use small taper pin reamers, you could JB Weld the hole up and come at it with taper pin reamers or... You could junk the hold mess and use a production back plate and external tank.
I suspect that as long as the air intake is larger than the venturi what ever you have at hand will work. Oh, one more thing, that stupid bronze screen can be poked out - it's just an air obstruction anyway.
HTH - Steve B.
PS Bruce as always feel free to edit or reorginize as you see fit.
Good question about the air intake. Back plates on the Cox reed valves come in a number of different flavors. The earliest were pot-metal with two vents, one on either side of the needle valve. I've never noticed any difference in these, but I've never looked either. Next came pot metal back plates that were made for their engines. Some have no vent at all; these were for the Golden Bees and Black Widows. Their tanks were vented and as a result the back plate didn't need vents. The intakes on these appear as large as 1/8" and some small as 3/32". I had two of these in my stash that are about 1/16". I don't know why this is. The next type of pot-metal back plates had a single tall vent and a short one at the surface. I can only guess these are a newer Baby Bee back plate.
Then, Cox started making their black plastic back plates. These are my favorite back plates because they are noticeably lighter than their pot metal counter parts. If you're trying to save some weight this is a good place to do it. I have specimens (junk in my parts box) from Black Widows (no vents), Baby Bee's and Texaco's. Again there are variations in the air intake openings from 1/8" or 3/32". The pot metal and plastic back plates have (relatively speaking) a course ill fitting needle valve that loves to screw in or out due to vibration when they are in the air.
The product backs plates are yet another type, very often have screens over the intake and vary often have a fine thread needle valve and seal (though not always). These are nice. The needle valve is easy to adjust and the seal locks them in place. They also have one other thing; they have a large air intake, and the closest thing to a venturi is the reduction at the needle valve seat, which is hard to see because of the screen and needle valve seat. Current sure starts (which do have the large air intake but have crappy needle valve and no seal) are the exception - sorry.
Is there any rhyme or reason for all of this (he asks rhetorically)? Not that I am aware of.
Having said all this the intake opening in the tank back isn't the venturi. The venturi is in the tank. It's the tapered tube that runs from its seat in the back plate to the reed valve opening.
If you are concerned about the air intake fit the tank against it and look at the actual venturi. It will be smaller than the air intake (except product engines) the venture in the tanks vary. The Black Widow starts out at about 3/32". The Baby Bee starts out about 3/32" and the Texaco starts out a bit smaller than 3/32". The exit port behind the reed valve varies also. So... if your going to using a Cox reed valve tank your stuck unless your very clever and paitent. You could use small taper pin reamers, you could JB Weld the hole up and come at it with taper pin reamers or... You could junk the hold mess and use a production back plate and external tank.
I suspect that as long as the air intake is larger than the venturi what ever you have at hand will work. Oh, one more thing, that stupid bronze screen can be poked out - it's just an air obstruction anyway.
HTH - Steve B.
PS Bruce as always feel free to edit or reorginize as you see fit.
01-09-2006, 11:14 PM
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RE: Cox Reed Valve FAQ
ORIGINAL: flybug
I believe indoorff article fits here, so here is the link http://www.nrg.to/doughtyhobbies/049tips.htm
Edit:
Hope we can make stikies out of these FAQ
I believe indoorff article fits here, so here is the link http://www.nrg.to/doughtyhobbies/049tips.htm
Edit:
Hope we can make stikies out of these FAQ
01-10-2006, 02:39 PM
#10
RE: Cox Reed Valve FAQ
On Martin H's site, in the Documents page, there is this link to a magazine report on the black widow, which is pretty close to being the sure start except for the differences[&:]
http://www.mh-aerotools.de/airfoils/...ugust_1974.pdf
http://www.mh-aerotools.de/airfoils/...ugust_1974.pdf
01-10-2006, 03:52 PM
#11
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RE: Cox Reed Valve FAQ
Kid, this is what I've got right now on the reedies. At home I've got some Surestart backplate measurements. I'll try to whip them up later. I'll put some CAD files on my site later also.
01-11-2006, 01:41 AM
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RE: Cox Reed Valve FAQ
While I have been somewhat verbose, the following is a photo collection of popular accessories (gotta have those). While alot of this stuff can't be ordered online, it can be found at swap meets or eBowow. You may have to pound on your buddies at the R/C field, that sort of thing.
Photo 1 is a Cox Pee Wee with a Cox muffler (yes these do work) along with a KK 020 back plate and needle valve.
Photo 2 is the same engine one the front of some kind of air plane with some kind of radio in it (until it's fixed it has a range of about ten feet.
Photo 3 is a Cox throttle ring and KK black plate on a certain engine.
and finally
Photo 4 is is of very good needle valves for Tee Dees. These were made by KK except the Blue one which is an Ace unit.
So, for your viewing pleasure:
Regards - Steve B.
Photo 1 is a Cox Pee Wee with a Cox muffler (yes these do work) along with a KK 020 back plate and needle valve.
Photo 2 is the same engine one the front of some kind of air plane with some kind of radio in it (until it's fixed it has a range of about ten feet.
Photo 3 is a Cox throttle ring and KK black plate on a certain engine.
and finally
Photo 4 is is of very good needle valves for Tee Dees. These were made by KK except the Blue one which is an Ace unit.
So, for your viewing pleasure:
Regards - Steve B.
01-11-2006, 02:01 AM
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RE: Cox Reed Valve FAQ
But wait...theres more.
Photo 1 is a Kavan fuel tank extention shown is for the Baby Bee. Seal these up with silcon sealer/adhesive.
Photo 2 is a crankcase plug for the 0.049/0.051 Tee Dee's. This may still be available from Texas Timers.
Photo 3 is of KK Timming gaskets. These were place under the cylinder to change the engine timing.
Enjoy - Steve B.
Photo 1 is a Kavan fuel tank extention shown is for the Baby Bee. Seal these up with silcon sealer/adhesive.
Photo 2 is a crankcase plug for the 0.049/0.051 Tee Dee's. This may still be available from Texas Timers.
Photo 3 is of KK Timming gaskets. These were place under the cylinder to change the engine timing.
Enjoy - Steve B.
01-11-2006, 01:12 PM
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RE: Cox Reed Valve FAQ
ptulmer- Thanx, very helpful for model planning stage.
Just got told the SureStart can't be used a s pusher because it lacks a thrust washer, but then the quality posters here at rcuniverse let me know I can retrofit a washer from a different motor on it. Perhaps this tip could have an indepth entry from the gurus here for others in my boat.
--edit- I see in the pic the crank has a spline for the driveplate, is that a hard press or can I get it of by hand. Etch a few radial oil lines in the face of the case, & cut a brass shim thrust washer. Then, the shim should go on and replace the driveplate? What does the propscrew tighten against... will it squeeze/bind the shim washer I install?
Just got told the SureStart can't be used a s pusher because it lacks a thrust washer, but then the quality posters here at rcuniverse let me know I can retrofit a washer from a different motor on it. Perhaps this tip could have an indepth entry from the gurus here for others in my boat.
--edit- I see in the pic the crank has a spline for the driveplate, is that a hard press or can I get it of by hand. Etch a few radial oil lines in the face of the case, & cut a brass shim thrust washer. Then, the shim should go on and replace the driveplate? What does the propscrew tighten against... will it squeeze/bind the shim washer I install?
01-11-2006, 03:20 PM
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RE: Cox Reed Valve FAQ
KE,
The crank is pressed onto the prop driver. No big deal to remove though, just screw on the prop bolt and give it a good couple hits with a hammer with the back of the case resting on a hard surface. I guess a piece of sheet brass would work for the thrust washer. I do believe the factory uses stainless steel. To put it all back together get the prop driver started back onto the crank by hand and mount a prop on it and tighten the prop screw and it will pull it all back together. The crank has a shoulder that the prop driver stops against.
LAter,
Tim
The crank is pressed onto the prop driver. No big deal to remove though, just screw on the prop bolt and give it a good couple hits with a hammer with the back of the case resting on a hard surface. I guess a piece of sheet brass would work for the thrust washer. I do believe the factory uses stainless steel. To put it all back together get the prop driver started back onto the crank by hand and mount a prop on it and tighten the prop screw and it will pull it all back together. The crank has a shoulder that the prop driver stops against.
LAter,
Tim
01-11-2006, 04:27 PM
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RE: Cox Reed Valve FAQ
This FAQ is paying off bigtime already.
I wonder why Cox decided to omit the thrust washer on SureStarts if it's just a SS or brass shim... it can't be for saving them $millions for a two cent peice of punched stock.
Thanx Tim
I wonder why Cox decided to omit the thrust washer on SureStarts if it's just a SS or brass shim... it can't be for saving them $millions for a two cent peice of punched stock.
Thanx Tim
01-12-2006, 08:48 AM
#17
RE: Cox Reed Valve FAQ
Also AFAIK, none of my Cox reedies have this.
You won't need this in a pusher configuration at first. Just check that the crankshaft can not be pushed into the reed assembly, and supply said washer before it does. It may have to wear some before you can even get a washer in there. And that may take many hours of running.
It probably isn't worth the effort. You can toss the engine and replace it for seven bucks.
Just my opinion. Your choice.
George
Edit: Removed first paragraph due to Tim's correction below. Altered next paragraph...I don't have a Killer Bee.
You won't need this in a pusher configuration at first. Just check that the crankshaft can not be pushed into the reed assembly, and supply said washer before it does. It may have to wear some before you can even get a washer in there. And that may take many hours of running.
It probably isn't worth the effort. You can toss the engine and replace it for seven bucks.
Just my opinion. Your choice.
George
Edit: Removed first paragraph due to Tim's correction below. Altered next paragraph...I don't have a Killer Bee.
01-12-2006, 09:00 AM
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RE: Cox Reed Valve FAQ
George,
The back of the prop rests on the prop driver. The thrust washer is a thin washer between it and the crankcase. The Killer Bee uses this.
LAter,
Tim
The back of the prop rests on the prop driver. The thrust washer is a thin washer between it and the crankcase. The Killer Bee uses this.
LAter,
Tim
01-12-2006, 09:33 AM
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RE: Cox Reed Valve FAQ
Ive been running a Cox product engine ( your guess) as a pusher for some time and its got no appreciable end float in the crank , BUT!!! it has the bronze prop driver, and black plastic backplate. I think these motors with the bronze propdriver were intended to be used as pushers ?
Stewart
Stewart
01-12-2006, 09:47 AM
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RE: Cox Reed Valve FAQ
SGC, I think the bronze thing is just from a certain time period. I have one that's about five years old. That about right for yours?
gcb, I don't know about the pusher config, but they wear relatively quick when using a starter. Like you said, after they wear down some, the washer fits nicely!
gcb, I don't know about the pusher config, but they wear relatively quick when using a starter. Like you said, after they wear down some, the washer fits nicely!
01-12-2006, 09:52 AM
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RE: Cox Reed Valve FAQ
Ye about 5-6 yrs ago i bought 1/2 doz out of a bucket of ex Cox warranty returns, there was nothing wrong that cleaning the needle/fuel inlet didnt cure.
Stewart
Stewart
01-15-2006, 04:18 PM
#23
RE: Cox Reed Valve FAQ
Thanks for the information on the Killer Bees thrust washer. I will look for it on the 1 I ordered with the Micro Bird. I use starters on everything now. My reflexes are just too slow.
01-15-2006, 05:50 PM
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RE: Cox Reed Valve FAQ
ORIGINAL: Tim Wiltse-RCU
KE,
The crank is pressed onto the prop driver.....just screw on the prop bolt and give it a good couple hits with a hammer.....
KE,
The crank is pressed onto the prop driver.....just screw on the prop bolt and give it a good couple hits with a hammer.....
Tim, Tim, Tim..... I'm shocked. You and I know that "a good couple hits with a hammer" means light taps that just move it enough to get it out but some folks may take this to mean "whack it like a 6 inch rail spike".....
I used to tap it off like you using a hammer but I found that I bent the odd prop screw and that the end would get peened down and not let the screwdriver in any more. Now I use a vise to push them off instead. I insert the prop screw all the way and then put the case and prop screw between the vise jaws using scraps of thin plywood or clean sheet aluminium as pads to prevent marking. Line it up so it's all in line and then push the crank out the back of the drive washer.
I re-install same as you do.
Some of the engines do not have much fore and aft play. For those it's going to be much harder to install a thrust washer. For the rest there's often a good 10 or 15 thou of play. You can test if the metal will fit by pulling the drive washer forward and inserting the chosen shim material. If you can slide it into the gap and there's still a degree of fore n' aft movement that you can feel then it's OK. I'd suggest something like 4 to 5 thou shim material. Even 3 thou would probably be fine. Any thinner and you risk the metal crumpling if something gets caught in there.
For the engines that are tight enough that you can't get the 5 thou shim in there and still have about 5 to 8 thou of play then you gotta get more serious.
A lathe would be the ideal solution to trim the case down by a few thou.
In a pinch you could use a drill press and a dremel end cutting burr to trim the case. In this method use the depth stop to ensure all the plunges are the same and take off only a very small little nibble at a time and then move the case about 1/32and take out another nibble to prevent the end burr grabbing and pulling it out of square. Just reduce the whole end by about the thickness of a couple of pieces of writing paper. That's about 6 thou the last time I checked.
You can even do it with a hand file. Pad and grab the case firmly but carefullly in a vise and take of a couple of strokes off the end with a fine tooth file. It would help if you put a scratch mark about 5 thou down on the outside and file down to that line. Use the crankshaft inserted from behind to check the progress for distance and rough squareness. Don't go too far and try to keep the cut end as square as possible. Now mark the filed end with a felt pen and push the crackshaft in from the nose end and turn it around a few times to scuff off the ink from the high spot(s) and remove. With a careful touch just file a one inch stroke off the shiny bits. Now re-ink and re scuff with the crank. Keep doing this until the high spots are cut down and you have an even scuff line over a good portion of the end face. Deburr lightly with the file on the outside and an xacto knife on the inside as you go to allow the crank to go in easily. As a final step I suggest a bit of 400 grit wet or dry with a hole punched in it and placed over the crank and use that to polish the end face a little and level out the worst of the remaining high points. Now wash it all up well with some hot and soapy water, dry, oil and assemble. The whole thing will take you about 20 to 30 minutes. Work slow and attentively and try to feel the seating of the file. It's fussy work but with the ink and some reasonable care similar to what you use already for general model building it's very doable. The key is to use the inking and scuffing to sneak up on the whole fit in very small steps. Especially when you start getting lots of shining points from the scuffing as that means you're REALLLY close to a great fit.
01-17-2006, 09:29 PM
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RE: Cox Reed Valve FAQ
Hey,
I recently bought a cox black widow. the cylinder is put on tightly but that is the problem. See, the cylinder is put on crooked, so that the exhaust ports are cocked sideways in relation to the crank case. I want to make them perpendicular to it. Thing is, I cant loosen the cylinder[&:] with the supplied wrenches. Guess i need to use something else, but what?
I recently bought a cox black widow. the cylinder is put on tightly but that is the problem. See, the cylinder is put on crooked, so that the exhaust ports are cocked sideways in relation to the crank case. I want to make them perpendicular to it. Thing is, I cant loosen the cylinder[&:] with the supplied wrenches. Guess i need to use something else, but what?