Which other brand engines can use our Cox head conversions?

Cox International Thu Jan 12, 2012 10:33 am

Just curious as to whether these products:

http://coxengines.ca/product.php?productid=116&cat=27&page=1

http://coxengines.ca/product.php?productid=362&cat=27&page=1

http://coxengines.ca/product.php?productid=450&cat=27&page=1

Will work with other engines.

We know they work on Novel but how about the AP Wasp 061 (Norvel copy?) or any other engines?

**RknRusty** Thu Jan 12, 2012 10:55 am

Cox International wrote:Just curious as to whether these products:

http://coxengines.ca/product.php?productid=116&cat=27&page=1

http://coxengines.ca/product.php?productid=362&cat=27&page=1

http://coxengines.ca/product.php?productid=450&cat=27&page=1

Will work with other engines.

We know they work on Novel but how about the AP Wasp 061 (Norvel copy?) or any other engines?

I can only answer with a question. Since I was given a Galbreath head with a Nelson plug, I've been wanting to switch to all adapters. The head and plug I have combine to look like the shape of a Tee Dee combustion chamber. I was wondering if yours, like in your second two links, have the same compression as the Galbreath/Nelson. And are they the same as a Cox high compression head? Also the one in your first link looks like a Cox standard combustion chamber. Is that the same compression as the regular heads? I've read that some adapters have a gap where the plug screws in causing lower compression. Can you give me the scoop on all that?
Thanks, Bernie,
Rusty

Cox International Thu Jan 12, 2012 11:42 am

Rusty,

The first link is for an adapter that goes with a standard 1/4" glow plug and, yes, it reduces compression and RPM. About 500-1,000 less on a reed valve engine and about 2,000 less on a TD engine.

Link #2 is a Merlin setup. According to Al from Merlin this setup not only equals but outperforms the Galbraith/Nelson setup. I would take that statement with a grain of salt as the G/N is known to be a top performer.

I did run a G/N setup on a Surestart as well as our #2 and the results were identical; aprx 1,000 RPM increase. I never did run either setup on a TD but suspect that both will perform about the same.

Our setup increases compression (too much sometimes, see notes on listing) and performs better than the OEM Cox TD head.

Link #3 is our invetion but still uses the Merlin insert. Performance is equal to #2 and is used by modellers wishing extra cooling (medium hot insert) or Texaco and throttled flying (hot insert).

However, if anyone has a G/N setup and wants to run comparison tests under like and controlled environment, I would be happy to supply a set of ours as I am curious myself, especially TD results.

Mark Boesen Thu Jan 12, 2012 12:27 pm

In ’59 O.K. Cub introduced their first glowhead. It was the same diameter and thread as a Cox .049/.051 glowhead. So it would work with any O.K. Cub .049 or .06 reed that has a glowhead in need of replacement...and i think a .074 as well?

nitroairplane Thu Jan 12, 2012 12:43 pm

Yes and the oK .074 I am 99.9% sure it will fit the AP wasp because I have seen them with Davis Diesel heads.

Cox International Thu Jan 12, 2012 12:46 pm

Thanks Mark and Nitro; that helps.

crankbndr Thu Jan 12, 2012 12:52 pm

I was thinking about trying the insert in Link 2, is the heat range marked on the insert? What heat range would work best for sport flying, control line?

nitroairplane Thu Jan 12, 2012 12:55 pm

crankbndr wrote:I was thinking about trying the insert in Link 2, is the heat range marked on the insert? What heat range would work best for sport flying, control line?

It depends on what fuel you run.
THe higher % nitro in the fuel the cooler you want your plug.

Cox International Thu Jan 12, 2012 1:28 pm

The only reason one would want a "hot" plug is for really low RPM as in throttled engines or oversized props for Texaco events. Or, if you are running something like 5% Nitro; which is too low anyhow for Cox engines.

"Hot" plugs don't last as long as the filament is thinner. They are just a necessary evil for throttled engines if one wants lowest possible RPM.

crankbndr Thu Jan 12, 2012 1:33 pm

Thanks for the info guys.

nitroairplane Thu Jan 12, 2012 1:36 pm

Cox International wrote:The only reason one would want a "hot" plug is for really low RPM as in throttled engines or oversized props for Texaco events. Or, if you are running something like 5% Nitro; which is too low anyhow for Cox engines.

"Hot" plugs don't last as long as the filament is thinner. They are just a necessary gevil for throttled engines if one wants lowest possible RPM.

Yes I run a hot plug on my texaco 5 fin head on throttled norvel.

**RknRusty** Thu Jan 12, 2012 3:26 pm

Cox International wrote:Rusty,

The first link is for an adapter that goes with a standard 1/4" glow plug and, yes, it reduces compression and RPM. About 500-1,000 less on a reed valve engine and about 2,000 less on a TD engine.

Link #2 is a Merlin setup. According to Al from Merlin this setup not only equals but outperforms the Galbraith/Nelson setup. I would take that statement with a grain of salt as the G/N is known to be a top performer.

I did run a G/N setup on a Surestart as well as our #2 and the results were identical; aprx 1,000 RPM increase. I never did run either setup on a TD but suspect that both will perform about the same.

Our setup increases compression (too much sometimes, see notes on listing) and performs better than the OEM Cox TD head.

Link #3 is our invetion but still uses the Merlin insert. Performance is equal to #2 and is used by modellers wishing extra cooling (medium hot insert) or Texaco and throttled flying (hot insert).

However, if anyone has a G/N setup and wants to run comparison tests under like and controlled environment, I would be happy to supply a set of ours as I am curious myself, especially TD results.

Thanks for the detailed reply Bernie. I'm going to get either one of the #2 or #3 adapters and try it on my engines. I don't really need extra cooling, because I don't throttle or run Texaco, but if it accepts the same plugs as the #2, I'd prefer it.

I don't yet have a tach, so I can't run accurate tests. I'll be placing an order in a couple of weeks when I have money and I'll probably get a tach at that time too. I want to change over to adapters on at least a couple of BWs and a Medallion. My G/N set is on my Tee Dee .049 right now and it runs very good.

Surfer_kris Thu Jan 12, 2012 4:11 pm

The VA .049 engine has the same threads as cox .049.

The CS .049 and .061 (i.e. Brodak MkI) has a similar bore in the case but you'll need another clamp as the threads are "external". A clamp can be made by simply drilling out the stock head (Brodak have had spare heads) to fit over the insert .

How about making a glow head that takes Turbo plugs? It is just one more machining step (to make the conical part) compared to making a head for a regular plug, and you don't loose any power...

Cox International Thu Jan 12, 2012 4:13 pm

Rusty,

The regular and extra cooling adapters both use the same inserts.

Cox International Thu Jan 12, 2012 4:34 pm

Surfer_kris wrote:The VA .049 engine has the same threads as cox .049.

The CS .049 and .061 (i.e. Brodak MkI) has a similar bore in the case but you'll need another clamp as the threads are "external". A clamp can be made by simply drilling out the stock head (Brodak have had spare heads) to fit over the insert .

How about making a glow head that takes Turbo plugs? It is just one more machining step (to make the conical part) compared to making a head for a regular plug, and you don't loose any power...

Thanks for the info.

We experimented with turbo-style adapters, unsuccessfully. We could have cloned the Galbreath one but would be stuck using the Nelson heads; which are of proprietory size and not as readily available as we would like.

So, we used other manufacturer brands with a more common thread but could not get our adapter manufacturer to correcly make one that would run well. We made a couple of attempts and achieved lower RPM's than the with the Cox OEM heads.

Each attempt costs $200 in re-tooling and machine shops are not designers; they operate with drawings. That is where we gave up and drew upon the Merlin stock; which performs quite well.

Even the tiniest variations in combustion chamber make a difference and Galbreath seems to have perfected this. We will leave this field to him.

Surfer_kris Thu Jan 12, 2012 4:52 pm

I respect you decision, but would just like to comment a little, just out of interest for the topic.

I don't really understand the problem. The Merlin plugs are very crude in terms of combustion shape, it is basically just a cone without a any real squish band.

You can easily copy that for a turbo plug too. I have made a few different heads for the TT 07GP, and just copying the stock head shape (also a conical one, but it has a squish band) works very well. A squish band makes the compression setting less critical.

The Turbo heads for Norvel (made by Valentine) works very well on the Cox 05RC too. The compression is somewhere between the stock low and high compression heads from cox, with the advantage that turbo plugs are readily available in different heat ranges.

Which other brand engines can use our Cox head conversions? Turbo_11

nitroairplane Thu Jan 12, 2012 4:56 pm

Surfer_kris wrote:I respect you decision, but would just like to comment a little, just out of interest for the topic.

I don't really understand the problem. The Merlin plugs are very crude in terms of combustion shape, it is basically just a cone without a any real squish band.

You can easily copy that for a turbo plug too. I have made a few different heads for the TT 07GP, and just copying the stock head shape (also a conical one, but it has a squish band) works very well. A squish band makes the compression setting less critical.

The Turbo heads for Norvel (made by Valentine) works very well on the Cox 05RC too. The compression is somewhere between the stock low and high compression heads from cox, with the advantage that turbo plugs are readily available in different heat ranges.

I see what you mean.
It would be cool to be able to use turbo plugs.
What kind of performace are you getting with that head from valentine?

Surfer_kris Thu Jan 12, 2012 5:03 pm

With the low compression cox head I got about 17000rpm on a 6x3 graupner prop and 10% nitro. This is a little undercompressed and would benefit from more nitro I guess.

With the Valentine head and an OS P#7 (Hot) plug I got about 17200rpm and a better overall running on the same fuel and prop.

As a comparison the TT 07GP did 17200rpm with its' stock regular plug head (same prop and fuel) but it can make 18200rpm with a Turbo plug head. The best I have seen on the TT was 18700rpm, but that was after some mods to the transfer channels in the case (not needed on their latest models).

Cox International Thu Jan 12, 2012 5:25 pm

There are a couple of reasons that we have no appetite for revisting the turbo plugs.

One reason is that, after our failed attempts, we discovered Merlin. There we can buy in small quantities of, say 100, as opposed to having to manufacture 1,000 at a time to get decent pricing. Furthermore, the price is right and Merlin has a product that works really well even though if it is perceived as crude.

Second reason is that why would we now want to invest $$'s into yet another product that will work about the same but would entail us investing larger sums of $$'s?

And the third, most important, reason is that our machine shops were not able to clone the combustion chamber. Sure, they could clone the Galbreath one but what we did was send them the Galbreath adapter and an OS turbo plug and said "make a product". They did 2x and the product looked great but did not perform. Cost us $400.

One has to understand that machinists are good in their trade but they are neither modellers, engineers, nor designers. They did their best and the prototypes looked great - they just did not perform well.

As for myself, I am completely useless in this respect, a klutz with tools and machinings innerly scream when I talk to them. Marketing is what I do.

Sponsored content

Which other brand engines can use our Cox head conversions?

Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?

Re: Which other brand engines can use our Cox head conversions?