burtcs

brED: the cylinder can be warmed up with a heat gun or propane torch (you're not trying to melt anything just get them hotter than you'd like to hold on to for more the two or three seconds). The heat will expand the crankcase a bit and you can remove the cyclinder. I pull the tank and prop bolt and GENTLY hold them in a vice to do this. DON'T worry about the exhaust ports not being perpendicular to the crankcase. It is an odd seciman when they are.

HTH - Steve B.

mclintock

My Feedback: (3)

What's the best method to kill the engine on a tank backed reedie when it starts backwards? I read in an old book once to toss a rag into the prop, but i've also read that doing that is not such a good thing for the engine.

I've been closing the needle valve to stop the engine when it cranks backwards, but I hate to do that, looses my 'place' with the needle and I worry about wearing the threads.

Usually i use the spring to start, but on my older pee wees, I don't have springs.. so I get a coin toss as to which way it winds up running.

gcb

Use the rag.

George

Edit: If your method of starting causes it to start backwards most times, flip it backwards using the "bounce" method. That is, flip it so that it does not completely turn over. If done correctly, it will fire off the prime and start it running in the correct direction. This also works to start non-reed engines.
What MAY be happening is that an over prime may cause it to misfire (fire early) and essentially give it a hard flip in the wrong direction. With a rotary or shaft induction it starves for fuel and stops. With a reed induction it happily runs.

Silvaire

My Feedback: (50)

I will present this as a observation, not as a recommended method:

If one has an engine with the standard TD type aluminum spinner, one can often just pinch the spinner between ones thumb and the side of one's index finger. This seems to only work well if the engine is running a bit rich and/or cold, and has not gotten too much RPM...

Generally, the big concern with any brute force method of shutting down the engine by stopping its rotation is not damage to the engine, but damage to the airframe. This is a concern when using a rag in the prop. Perhaps using the hollow end of a chicken stick on the spinner to stop the engine might be a bit safer for the operator than just using fingers. This method puts less stress on the equipment than a rapid stop from a rag. If we are talking about something fairly overbuilt like a trainer or most any kit built C/L model though, the rag in the prop likely won't harm anything.

Arlen

KidEpoxy

Just what is the thread on the SureStart prop screw.. they didn't do something silly like use a standard thread like 8-32 did they?

BMatthews

Good question-

All the 049's use the same prop screw size. It's a 5-40. Some are longer than the others to suit the little spinners or just basic screws but they are all 5-40 thread. They apparently picked this odd size because it works out that a 5-40 is a lovely fit into a 1/8 hole.

Unfortunetly this is an odd size these days for many. The best bet is to locate an industrial screw supplier and order up a box of 100 in 3/4 and 1 inch sizes and then divide the order between a few local modellers. The 1 inch is for use with the TeeDee and Black Widow style spinner cones. Doing a quick google I find that 5-40 is not common out there either. But the following online folks have them as of this posting date...

www.boltdepot.com - in allen cap style only. box of 100 for 3/4 is $5.85 and 1 inch is $19 .
www.fastener-express.com has the same allen cap sizes at about the same prices but only sells the longer size in lots of 10 for $2.84.
http://www.swapmeetdave.com/MachineScrews.htm has 7 boxes of 5-40 x 1 1/2 long cheap round heads that are a bit rusty but come with some nuts available for 0.50 each. (obviously shipping will be more than that)
www.grainger.com has standard round head screws. 3/4 - $3.63 and 1 inch - $8.04

KidEpoxy

gah, a #5 screw
sometimes I think guys are just trying to make things harder than they have to be.
Thanx for the speedy info... I love this thread

burtcs

Bruce et al: While poking around on the "Everything Diesel forum" I noticed someone inquired about Cox diesel conversions. This has been beat to death here but a very useful list of Cox parts emerged. I am shamelessly encluding the URL here. Well worth a look if you've ever wondered what a #9 cylinder came out of. Use the printer friendly version for a print out - hey I got mine 8).


http://www.clstunt.com/htdocs/dcforu...ID1/17842.html

HTH - Steve B.


[8D]

Silvaire

My Feedback: (50)

Another EXCELLENT source for hardware is McMaster Carr. http://www.mcmaster.com/

Of course they have 5-40 screws. In 3/4" length, they list 20 DIFFERENT items. (This includes various combinations of steel, stainless, brass, round heads, flat heads, socket heads, slotted, phillips, etc., etc.)

Prices are good too. For example: round head plated steel 3/4" 5-40 screws are $3.79 per 100, and stainless steel socket head 1" 5-40 screws are $10.44 per 50. If you want a stock looking screw but in stainless for use with a TD style spinner, the 1" round head screws are $9.83 per hundred.

I have had excellent service from this company, even when dealing with a problem on their part. Their selection is just short of unbelievable. To them, 5-40 threaded hardware is common stuff. While browsing their online catalog, I happened to see that they even carry 5/40 allthread (take your choice of brass, stainless, plated steel or plain steel). This is just another example of their substantial variety of hardware.

Arlen

calmat

My Feedback: (70)

Maybe this has been answered before but i want to know why some cox o49 engines have two large exhaust ports and some have 4 small slits. How does performance differ if it does.

magic612

Try The Nutty Company too - I used to live near them. They have all kinds of standard and odd sizes (including those 5-40's!)

http://www.nutty.com/

3/4" length - $5.40 / 100
1" length - $6.30 / 100

Lots of other lengths available, too.

mclintock

My Feedback: (3)

This link I swiped from the rcg version of this forum, but it's too good not to pass everywhere.

Castor oil- why? Well now you know:
http://modelenginenews.org/faq/index.html#qa5

Short answer, because instead of burning off during a lean run, it actually thickens in high temps, where synth would just burn off, leaving the metal bare when it needs it most! It's easier to clean off castor varnish than to put metal back on.

I put this here 'cause cox engines are more likely to be running with no throttle than a norvel, where if lean one could just throttle down and land.

gcb

Long version:
This is especially true of an iron piston/steel cylinder combo because as temperature rises, the fits get tighter, which causes even more heat until you get "thermal runaway" which can ruin an engine. Castor turning to varnish would cause the engine to slow down to some degree which lessens the extreme heat production. Most synthetics flash off at this point and allow the engine to wear out with metal to metal contact.

ABC engines provide for the cylinder to expand more than the piston which prevents thermal runaway. If the lube reaches its flash point more than normal wear will occur but usually not to such a large degree.

BTW, iron/steel setups allow a varnish buildup in the pores of the iron piston which will compensate for a lot of engine wear. If your engine is showing less compression, sometimes switching to all-castor fuel will buy you some compression as it runs. ABC does not do this because of the high silicon pistons.
Conversely, if your iron/steel engine has a lot of time on it and you switch from all-castor to part synthetic, you may find that your engine is worn out. Switching back to all-castor can restore at least some of the varnish seal.
One of the hottest parts of an engine is the top of the piston. In a Cox engine, directly under that hot spot is the ball socket. With over lean runs and all-synthetic lube you run the chance of the lube flashing off and leaving the ball socket unlubed. For this reason, fuel for Cox engines should contain some Castor oil.

In the other direction, when Cox fuel was all Castor we had to tear the engines down occasionally to remove varnish if we ran them hard. Some synthetic in the fuel prevents or lessens varnishing.

There are some synthetics that are touted to be just as good as Castor. Unfortunately, not all fuels use these types.

Bottom Line: Your engine, your choice.

Sorry if this seems like a lot of rambling. I've never met an engine I didn't like.

George

mclintock

My Feedback: (3)

Does that Norvel NVX 1/2a fuel need to have castor added? I have some of that, and after running an engine in the house, I noticed the taste in my mouth whilst breathing the smoke was different than the fuel I was running that I knew had castor, since I added it..

I bought the nvx for the express reason that I thought i'd not have to add castor, so I'd know what the percentage of nitro was.

Wayne C

penzoil claims that their automotive senthetics are less likely to burn off in high temp situations than natural oils. i have been under the impression that glow engines generally run cooler than many high performance auto engines. ????

ptulmer

My Feedback: (5)

Clint, I emailed Norvel that question one time. They didn't know. I don't have a copy of the email, but it was from someone at Sig. Justin? Anyway, the email stated flatly that Klotz is synthetic. Well, no it's not! It's a brand name that sells synthetic and castor. Another non-answer from someone who doesn't care. I would have expected better from them though.

Andrew

As Patrick said, KLOTZ is a lubricant company, not a product. When Wildcat Fuels out of Nicholasville, KY was mixing NORVELs NVX fuel, the oil content was a mixture of KLOTZ Techniplate and BeNOL. Techniplate (there are several blends) is one of KLOTZ's synthetic series lubes. BeNOL is their racing castor lube. I have no idea what oils are in the SIG NVX fuel or what the synthetic/castor ratio might be.

The tech sheets for KLOTZ are [link=http://www.klotzlube.com/technical1.asp]here.[/link] BeNOL (all castor) is BC-175. Original Techniplate is KL-200, ModeLube Techniplate is KL-310 and Super Techniplate is KL-100. Super Techniplate is an 80/20 synthetic/castor blend.

When looking at the tech sheets, notice the burn rating (how much carbon buildup), the film strength (how "sticky" the lube is) and the flash point. Castor has the highest flash point and doesn't burn out leaving you high and dry.

In addition the points George made concerning castor, since it does not burn easily, it is expelled as a liquid and carries a great amount of heat with it. When the other oils flash off, they contribute to heat buildup and high heat transfer is lost.

I use BeNOL as my castor additive if the commercial fuel has a low castor content.

KidEpoxy

How bad of a person am I if I don't use the fabled "Piston Reset Tool" on a new SureStart... I'd hate to have to spend $20 to get a tool for a $7 engine. I'm not looking to make an UberScreamer, just fly around on 15%nitro

combatpigg

My Feedback: (3)

A loose ball socket will cause erratic runs and eventually allow the engine to hammer itself to death, instead of lasting for decades, like many well kept COX engines can. The engine will never run like it could, as a smooth, tight unit. I didn't know that reset tools were $20 now! They will run with sloppy ball sockets, but the question is, for how long?

KidEpoxy

I was just ballpark guessing the $20 tool, figured the shipping in too

What about a homemade throttle for the SureStart, something to gatevalve the choketube with a link to an arm on the needle to lean up for the low air, rich up to normal WOT? Just a stab at this, but basic concept before geometry throw ratio calcs... possibly need to use the ghosted length on the needle arm to get less needle travel for the throttle travel

Remby

My Feedback: (3)

CALMAT;

I have heard / read that the slit type was a attempt to cut down on a fire risk. As far as running, it ran like the others that had the same config.. (IE bypass, flutes, etc.)

Alkso, I posted some time ago about a mod to the surestart, or other slit type cylinder to get sub induction. I still do this and it works very well for the reedies as well. Following is the post..

This is a description on how to get sub induction from a Cox, "slit exzaust" type of cylinder. These cylinders normally did away with induction for Muffler, & throttle adapters. However, a loss of 20-30% in power is a large cost, so if you have the need for more power, perhaps this will give some aid. This has been tested and works well, however I am sure this is not the only, or even the best method.

This requires a couple of hand tools, and a small nylon twist tie, and about 1/2 hour of time.. I have done this engine mod. on a few of mine, and it works very well. One engine with the mod has been in use now for over 20 hours and works fine. I first did this on a older, worn cylinder to see if it worked, and it gave that one new life and added that old style power. A couple words of caution to the young (or young at heart) are in order. First, if you have doubts, get some help, and/or try it on a older, used slit type cylinder to see what is the work involved. You could make the cylinder unusable if you damage the bore, or even injure yourself. So, if you are unsure, don't try it without help. The mod can not be undone, and will probally make mufflers/throttle sleaves run a bit less reliable, so should be done on engines that will run (Full tilt) until the fuel is gone. So, if this sounds good , give it a try.

First, the tools needed are...

(2) Hacksaw blades (both used without handle).
(1) Regular screwdriver, about 3/16" wide blade tip.
(1) Nylon twist tie.
(1) Cox slit type of cylinder.
Small amount of alchol for cleanup
Fine steel wool
light machine oil
couple of paper towls
black permament magic marker (optional)

1.- Test fit your Cylinder with it's piston, this gives a reference for how it should feel after the mod is completed. Now, working with the cylinder. The small cut is done to widen ONE of the lower slits (closest to crankcase). First, attach the nylon twist tie around the cylinder below the slits. Insert one hacksaw blade in one of the lower slits, only insert it upside down. This first blade is used as a guide. The second blade is placed on the cylinder, right against the other blade that is in the lower slit. Slide the nylon twist tie against the blades as a lower guide ,this helps prevent the blade from sliding around marking up the lower part of the cylinder. The cut is made right beside the lower slit, the idea is to widen the slit. Start cutting, holding the upside-down blade in the slit, let the cutting blade ride right against the upside down one in the lower slit. just let the blade do the work, and check often as it usally goes quite fast, even by hand. Wear eye protection , and gloves to help prevent cuts. Keep cutting until the new cut is as deep as the stock slit on both sides of this one slit. After you get this far, don't go any deeper as this step is now complete. Remove both blades, and the nylon tie.

2.- Next, take the flat screwdriver, and remove any extra steel from the enlarged slit. This must be done CARFULLY from the inside of the bore, go around the edges the new cut to clean off any extra bits of metal. Make sure NOT to hit/scrape the driver on the bore itself, just the slit's edges that must have thin hanging steel bits, the bits must be removed . After this is done, drop the cylinder in a plastic cup of alachol. Swirl it around to remove the debris. Remove it and dry it with the towels.

3.- After it is checked and confirmed clean, carfully test fit the piston. If it stops, or you feel any grit, carfully remove it and check for burrs, or bits of metal. Repeat step 2 , then recheck the piston fit, it should feel the same as it did prior to the mod. Keep doing this until it is no different than before you started.

4.- Now use the steel wool and go over the inside of the bore, this will find and remove any minor bits of metal, and is easy to do. Reclean in fresh alachol, then dry the cylinder. .

5.- The magic marker can be used now to cover any unwanted scratches on the cylinder, this is optional, but covers any scratches well.

6.- Now light oil, the reasemble the engine.

This mod is great for those without machine tools, being all hand tools are used just aboue anybody can do this , Work slowly and make sure to clean the cut area well . If done as described, you will get that older Cox cylinder power, a noticable bit of improvment to your favorite model. Again, this mod works and is reliable, but perhaps it's simple method is not the best for those interested in speed or racing, Then again ...

Hope others may find this as useful as I have...

Remby

mclintock

My Feedback: (3)

While you've got your hacksaw out, you can make a throttle for the sure start.

I'll add pictures later, but it's simple- cut a length of 1/2" copper pipe (the potable water kind, not the heater system kind, although the thinner heater type may work too) to the distance between the top of the crancase and the bottom of the lower fin on the sure start piston.

I cut mine about a mm longer then filed it to size by holding the little length of pipe against the cylinder to check the length, since the diameter of the 1/2 inch pipe is just a little too small to fit on the cylinder. Using the hacksaw, cut along the length of the copper piece, so you can spread it open to make it larger in diameter to fit the cylinder. De-burr the edges and clean the copper chips off the ring.

It grabs on the cylinder tight, I used the tail of a file to spread the ring when cramming the ring on. Now you can screw the cylinder back on to make sure of the length of the copper, it should be close but not pressing against the crancase when the cylinder is all the way on.

Now pull the ring off and heat up the soldering iron, find some 10 guage or therabouts copper solid wire, strip about two inches of the wire and pound it some with a hammer to flatten it. The idea is to make an arm for the servo wire, so the pounded wire-turned-bar should be wide enough for a small hole to be drilled near one end for a pushrod.

Tin the ring on either side of the hacksaw cut, then tin one end of your flattened wire. This will be soldered in place across the gap in the ring so that the copper pipe ring will be held open when in place on the cylinder, so when it gets lapped it will stop trying to spring shut.

That gap forms the moving window that opens and closes the exaust port. I drilled a hole for the other port opposite the gap.

The flattened wire must be soldered in place with the copper fitted to the cylinder. Then it's lap time. I have been using car rubbing compound, and that's going very slow, I wish I could find my valve grind compound, but it's been 20 years and three houses ago since I saw it. Hopefully I'll twist enough with some polish in there to loosen it enough that a servo can move it. Right now it would take a 1/8 buggy steering servo to turn the throttle!

I should have tried this without drilling a hole for the other exaust port, but too late..

The ring does not interfere with the plastic back plate, which I need to put back on and try. Note this isn't really a sure start, it's a product engine out of a p51 from the Ford administration.

The picture will help now.. I'll post then edit so I don't loose this epic.

This is just food for thought.. this took way longer than ten dollars worth of time, and the cox rings are still available on the cox site for about ten dollars, under the parts for medallions listing..

KidEpoxy

Clint- Nice [8D]
Makes a swell spot to solder on the exhaust pressure pickup tube too.
Or just place the pickup tube strategicly to get shuttered at low throttle to reduce the fuel push for low rpm

hmm, like I told Sneasle... I should try it before messing with it.
but I'm gonna need a whole bunch more SureStarts to use up a 10' copperpipe a 1/2" at a time

I'm thinking PaperClip for the arm... they can pound pretty flat. Then I dont have to ask the guy at Home Depot for just 2" of 10ga solid

mclintock

My Feedback: (3)

Look around the breaker panel at your house/apt or office building, there's usually some scraps of nm ('romex') wire laying around on the ground. That may be 12 awg I used, I can't remember. Coat hanger may work too, a paper clip may be not enough to drill a hole in and it has to be strong enough to keep the gap exactly the same even as the insides of the copper pipe are ground away some by lapping. Plus sometimes when you solder to a paper clip, the chrome plating separates from the wire and the joint fails.

I don't know if a pressure nipple would be worthwhile- the reedies draw fine- it's the Tee Dees that get all fussy unless the fuel pickup is just so.
But tee dee's have the pressure nipple on the side, and can be tapped for a pressure nipple in the center of the back plate.

I want to make another just to see if not having the hole for the second exaust port makes much difference.

GrahamC

I have been playing around with trying to get a better needle valve fit on the tanked reedies.

I took an old plastic back plate and "shaved" it down to reveal the inner structure of the needle valve and fuel feed. So far it looks pretty simple and I have taken measurements adn will post those numbers once I get myself a bit better organized. In the mean time here are a couple of photo's of the back plate and need valve assembly (with needle valve closed).

So far my experiment to drill out and tap the assembly 5-40. My idea so far is to tap a piece of brass rod 5-40 and fit into the back plate with some loctite. This brass rod will be drilled out (before fitting into the back plate) and threaded 2-56 for a gound 2-56 bolt to use as a needle valve or just drilled and lapped to a fine fit for a 1/16 needle valve with the needle valve fitted with a brass piece like the PAW type needle valve assemblies. Not a very good description, see photo 3

cheers, Graham in Embrun near Ottawa Canada