jayd3

Great discussions
I have learn a lot
Still wonder why the cox engines of the 80s-90s were crap? I'm convinced it was not the change to a mylar reed as many thought.

I would like to see a discussion on glowheads Cox made a standard for reed engines and a TD glowhead, and now there are several different glow plug adapters available??
Am I correct that the TD head marked with a circile of straight serrations were (I don't believe they have been made for years) higher compression ?

Thread Lockers
I am well acquainted the thread lockers being discussed having used them all for many years : the Red, Green, yellow are all very similar just having different break free strengths and temperature ranges; high heat will basically liquify these,
The blue is different from the others in that it does Not break free but will continue to resist for the complete coated thread. I have seen small soft screws with ruined heads and even broken off because of the blue's never breaking free.
I would not use the blue unless I could not find another that worked for me. I would have though silicone sealer would be to thick but if it works with out getting in things you don't want it in why not ? Shellac based sealers Permatex Aviation Grade 1 &2 my favorite for general use on gaskets can't be used because they are dissolved by alcohol.

Jay

aspeed

I think the mylar reed is a upgrade. I have heard at some point the original piston material was no longer available. This probably led to the rougher finish on the newer ones, or maybe just pushing the parts through faster could be the problem too. The red Locktite is the permanent one I think. That is all I use. If I need something removed, I don't use any thread lock. I think heat will remove it, although I always have got them out without heat. I only use the swirl mark TD heads. The dished BBee heads are not worth the trouble IMHO unless you need an idle or less power for some reason. I should edit this, I use the Merlin plugs too.

binns aero

I run GCBM Glowplugboy Rocket Power 24 ( 24% nitro,17% Castor) great runs about 50 flights,back plate came loose one time, thats it.

jayd3

I've seem lots of converter heads so you can use a regular 1/4 -32 glow plug but which one is good? and what and where is Merlin ?
I got a conversion head a few years ago but the only way I could get good compression was with a long std. plug and even then it seemed to give low compression.
One trick I'm going to try that a guy uses with OK Cubs is sealing the glow head threads; he uses silicone sealer, I think maybe a high grade Teflon containing pipe dope may be even better as it is intended to be a thread sealer, where silicone sealer is a surface sealer., will need to check the temp rating of the product selected but I know there are ones for high temp high pressure applications like steam.

Jay

aspeed

http://merlinglowplugs.com/Aircraft.html I get the 2019 A It included the clamp ring, and you get 3 plugs. Al Kelly is the owner and near Chicago. Nice guy, I always get my plugs when I see him at the Toledo show, to save shipping. A conversion head will cost more, and you still need to buy plugs. Some Nelson or Turbo plug conversions are fine, but the Merlins work fine, and are cheap too. The Cox TD plugs are good too, but may be more than $5 depending on your source. I use the Merlins, and make heads for odd size motors. The conversion heads were popular when the Cox company looked like it was finished, but now things are better.

Mr Cox

None of the conversion heads are any good, it is as simple as that.
(they can be reworked if you have a lathe, but will never perform as well as the heads with integrated glow wire)

Merlin inserts are possibly the easiest source nowadays. They are high compression ratios though so you will need a few extra head-shims.

jayd3

Thanks for the link
This Merlin knows their stuff and is not just throwing there plug at you and saying one size fits all.
More nitro, higher compression is going to make more heat just like it does in full scale engines so you need the plug for the fuel and engine.

Jay

Andrew

Here's a link to a major supplier of COX products, plugs included.

http://coxengines.ca/top-end/

gmeyers

Just ran across this. I strongly disagree - I own 6 or 7 of the 80's, 90's. (as well as some 60's, 70's) era Cox engines and I see no slump in quality or performance. The piston/cylinder assembly's work on the old or new engines with little or no difference in performance or in my case durability. Actually it is amazing that you can take a part made in the 1990's and it fits perfectly on an engine made in the 60's - that's a level of precision that's hard to find in most pre CNC industries Also while I like Merlin plugs I like Nelsons even better. They seem to improve performance in all my engines and are easier make adapters for with good results .one change that may have caused a difference in performance in the 80's and 90's vintage engines would have been the fuel - most fuel manufacturers went to synthetic oils because of the advent of ABC technology while the mehanite/steel pistons/cylinders of some manufacturers including Cox demand some real castor to prevent undue wear and gaulding of the parts.

GallopingGhostler

The quality in Cox engines started to slip when Estes Industries, the model rocket kit and engine manufacturer acquired Cox in 1994. They did not know how to match pistons to cylinders. Cox had a special set of employees trained to match piston and cylinders for perfect fit. Anyway, I am told some engines were a little tight, others had hardly any compression. Also they were mixing and matching performance engines with sport engine parts making them compromised performance engines. By 2004 they were selling product engines, the Sure Starts in their surplus sales outlet at $7 per pop, After, the engine division folded. Folks like Cox International, Ex Model Engines and a few others purchased the remain engines and parts stock.

There were some less successful engines toward the end of the Cox pre-Estes era. I bought their .049 R/C Bee in the early 1980's, really liked the engine. It made my Sterling Minnie Mambo on Ace R/C Pulse really fun with Ace KRD quick blip sequential throttle and was more powerful than the Babe Bee even with muffler on. I wore out a piston and liner with so many flights, I replaced the set with new. Die cast crankcase was still good, not excessively worn. But that engine was short lived. It was later replaced with the Dragonfly with greater fuel capacity.

I also bought their .074 Queen Bee back in the late 1980's. It was short lived, although as powerful as the .049 Tee Dee but with a decent throttle, was heavy and awkward to mount. I wondered why they didn't simply come up with a lighter weight .074 Sure Start styled crankcase and back with muffled exhaust throttle. Heavy is never good for a plane engine.

gmeyers

I took a queen bee .074 and removed the piston and cylinder then I made a bushing for the connecting rod of a TD .09 to fit the crankpin of the .074 and put the .09 piston and cylinder on the .074 threads are the same. So I had myself an .09 queen bee. - frankly it ran pretty good - great throttle response and sorta good power but not quite up to TD .09 power but much better than the .074. Still was a rear intake, reed valve and the weight remained a consideration. Had to use the .09 glow head because the queen bee's high compression head didn't work .

gmeyers

One thing I do remember about Thimble Drome and Cox was that a piston made in a production run from the 1960's would fit a cylinder made in the 70's or 80's and visa versa - that was a level of production consistency that is difficult to match.

GallopingGhostler

Yes, gmeyers, I remembered a little of your post in another thread, thought it rather ingenious that you came up with a decent "reed valve Medallion" .09 engine. I thought it interesting that Cox took a .09 cylinder and didn't bore it as much, leaving a heavier cylinder with thicker walls. There was need for a Cox to compete with the .061 Schneurles. Had they come up with a cheaper solution, which I envisioned as a .074 Sure Start with a very lightweight exhaust throttle like their .09 Medallions, a short nose for lighter weight, I think they may have had a successful formula with a reasonably cheap to manufacture engine.

Sure, the machined aluminum muffler was a nice touch but it was heavy, too, and more expensive to manufacture than their already tried and true exhaust throttle muffler. It was Cox low cost reed valve engines that put them in the number one position back in the 1960's, other manufacturers could not compete.

I'm wondering if one factors in all the crazy changes to business laws in California and high cost of employee living just made it too difficult to do business and compete. But then, Fox in Fort Smith, Arkansas was struggling too. I think that foreign manufactured engines being imported for much less cost due to their lower wages and lack of environmental laws spelled the death knell to our model engine industry. The last decade before Fox went out of business, the engine manufacturing was a side business, main was manufacturing parts for other concerns. Plus, interest in model airplane flying has been dwindling.

aspeed

In the 1980s things really changed with the CNC machining. I know where I worked that anything that was the least bit repetative was much faster to run on a CNC. I think it was said that one CNC replaced 14 conventional machines. I would sometimes run 3 at a time as well. That really brought the prices down, and the old Cox production machines were a bit outdated. They would have been competative, still but the old designs would limit them to bar machines, like the round cylinders and poor muffler designs which were needed later on.

GallopingGhostler

True. In a similar vein, Leroy Cox had come up with machining methods that would put his Cox engines above all others using the latest technology available at the time. What I think really killed Cox was importation of foreign engines that were priced cheaper than theirs. Their Conquest line of Schneurle ported engines were to propel them into the 21st Century, but they never took off IMO because of the competitive disadvantage due to lack of tariff enforcement. They, Fox, K&B have all passed on. This goes the same for even the US radio control equipment industry. Tom Runge at Ace R/C mentioned they could not compete because RF decks and components were cheaper to produce in Japan. They, EK Logictrol. Orbit, Kraft, and etc. vanished by the 1990's.

aspeed

Yes the Conquest was the best Cox ever. I only have one, and am afraid to use it, as Mecoa does not seem to support it. Grr. I think the decision was made to end Cox around the same time the Conquest was designed. Electronics were another technology that went crazy. My wife made mini calculators when they first came out. They were like $60 at the time, and pretty useless really $60 was a lot when you made $1.50 an hour.. Things have really changed since then. I still wonder how some of the brushless motors and ESCs are made so well, and cheap.

fredvon4

gmeyers...did you read from first page in 2006??
mid 06 and 07 were a hoot

gmeyers

I read some from both but missed any 'hoots' - what am I missing ??

GREG DOE

Aspeed, I think Ron Young may still support the Conquest .15? What may be of interest is the history of that engine. At one point Cox, and K&B were owned by Leisure Dynamics. The exec's at Leisure decided it was a better fit for K&B to build the Conquest .15, and let Cox focus on the smaller engines. K&B was later bought back by John Brodbeck ( with backing from a silent partner), and continued production of the Conquest .15 re-badge as a K&B.

aspeed

I retired the Conquest now. I really like the ASP blue head .15 now. I have had great results with a new turbo head. Better than the Conquest oddly enough as Chinese stuff goes. They are getting hard to find now too. I like to have three examples of motors now, especially as manufacturers seem to be going extinct. I only have two blue head ASPs so far. I can use them no prob. I suppose when the Conquest went to K&B it may have been related to the K&B casting facilities.The thread from the 2006 era has some old names in like Combatpigg and a few others.Just to keep somewhat on topic, my Queen Bee .074 idles really well now with the mod that I read somewhere. You drill a 1/16" hole in the carb body at a certain point, there is a drawing floating around somewhere. I made the hole a bit smaller than specified, and it idles quite low and steady. It didn't before the air bleed hole.