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Question - Mecoa Glow Plug Adapters - 6/25/2008 12:35:47 AM   
franklin_m


 

Posts: 125
Joined: 11/17/2005
From: Lemoore, CA, USA
Status: offline 		Wonder if anyone can help.

I've read a lot of the discourse on the glow plug adapters for Norvel engines, and I understand that I may lose some power by using one. That said, scarce Norvel plugs and the undeniable convenience of using regular glow plugs is enough to make me want to try one.

That said, I'm looking at the two offered by Mecoa. The say one is for "standard long plug" and the other is for a "standard short plug." I generally use Tower Hobbies plugs, and my question is should I get the short plug head or the long plug head? If it turns out the Tower Plug is somehow in between (and I'd not be surprised), then my next choice would be the OS A3. Same question would apply.

Thanks,
Frank

       Post #: 1

RE: Question - Mecoa Glow Plug Adapters - 6/25/2008 7:11:46 AM   
Mr Cox



Posts: 385
Joined: 7/20/2007
From: Gothenburg, SWEDEN
Status: online 		It is not that you may loose some power, you will definately loose power...

What you need is a head for turbo plugs, these are e.g. made by Valentine and are available at ebay.


(in reply to franklin_m)
       Post #: 2

RE: Question - Mecoa Glow Plug Adapters - 6/25/2008 11:54:17 AM   
flyinrog



Posts: 5741
Joined: 9/3/2002
From: Burlington, NC, USA
Status: offline 		Or the Galbreath (sp?)head with the Nelson plug..Larry Driskill may have these in stock, not sure...Rog

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RE: Question - Mecoa Glow Plug Adapters - 6/25/2008 9:29:48 PM   
franklin_m


 

Posts: 125
Joined: 11/17/2005
From: Lemoore, CA, USA
Status: offline 		Guys. Thanks. I know that I'll lose power, but the convenience of using the same plugs I use in other engines is just too much to pass up. Do either of you know which head would be used with the A3 or the Tower Hobbies?

thanks,
Frank

(in reply to flyinrog)
       Post #: 4

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 1:25:06 PM   
flyinrog



Posts: 5741
Joined: 9/3/2002
From: Burlington, NC, USA
Status: offline 		The turbo and nelson plugs are almost closed end much like the glow heads....the regular plugs are gonna open up too much space and reduce power and compression, if you can order a few of the throw away cox product engines, those glow heads will fit the norvel .049 and I think the .061 too...Rog

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Ever walk into a room and forget what you went in for?...ADHD, welcome to my world,it happens everyday!

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RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 5:40:44 PM   
TGC



Posts: 17
Joined: 3/25/2004
From: Lakeview, OH, USA
Status: offline
quote:

ORIGINAL: Mr Cox

It is not that you may loose some power, you will definately loose power...


.


I don't doubt the verity or validity of your unequivocal statement for a moment; but, I can't seem to find any empirical basis for it.


I hear this same subjective opinion expressed every time this question is raised, so it must be true!


Has someone, somewhere ever taken the same engine, same day with the same fuel, same prop and switched out all these adapters and plugs and written down their findings?


I'm not competing for the World Title every time I fire up my Tee Dee .049, but I'd like to know how many RPM's I am missing by using the Mecoa Short adapter and a Fox Std. Short plug.


Thank you for your help, Tom


.

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TOM ~ AMA1940

(in reply to Mr Cox)
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RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 5:57:31 PM   
Mr Cox



Posts: 385
Joined: 7/20/2007
From: Gothenburg, SWEDEN
Status: online 		I have tried it once on a Babybee but didn't bother to tach it, it just didn't sound right...

(If I can find the head again I could tach it, but I might simply have thrown it away in discust )

On other engines the difference will be around 1500 rpms.

< Message edited by Mr Cox -- 6/26/2008 5:58:15 PM >

(in reply to TGC)
       Post #: 7

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 6:02:47 PM   
TGC



Posts: 17
Joined: 3/25/2004
From: Lakeview, OH, USA
Status: offline
quote:

ORIGINAL: Mr Cox

I have tried it once . . .

. . . the difference will be around 1500 rpms.

.


You were comparing what to what?


Thank you for your help, Tom


.

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TOM ~ AMA1940

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       Post #: 8

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 6:19:14 PM   
Mr Cox



Posts: 385
Joined: 7/20/2007
From: Gothenburg, SWEDEN
Status: online 		Ok, I haven't tached any cox with and without the "adapter". I could tell the running was poor anyway...

Other small engines like the TT GP-07 shows a 1500 rpm improvement when going from standard plug to a turbo plug (a turbo plug is then similar, in terms of combustion chamber, to the original cox head as no threads are included in the combustion chamber).


(in reply to TGC)
       Post #: 9

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 6:52:01 PM   
TGC



Posts: 17
Joined: 3/25/2004
From: Lakeview, OH, USA
Status: offline 		.


Well done, Mr. Cox. Thank you for your help.


Would anyone have any quantitative data?


Thank you very much for your help, Tom


.

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TOM ~ AMA1940

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RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 7:16:47 PM   
uliner


 

Posts: 99
Joined: 4/19/2004
From: milwaukee, WI, USA
Status: offline 		Here is some data no numbers.

1/2 a control line baby flite steak, TD 049, cox 5x3 rubber ducky prop, Norvel 1/2 fuel, 35foot 008lines

COX standard plug, easily do the stunt patern,

A standard plug adaptor, aircraft was 10-15 mph slower and would bareley loop, ran like it had a head leak or about 15 extra gaskets.

Same fuel, same plane, same prop, same day.

Nelson plugs last a long time. I have not worn out many flying 1/2a.


Get the galbreth head and 2 nelson plugs and you will be set for a long time.
Or fool around for a few weeks and be frustrated.

(in reply to TGC)
       Post #: 11

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 7:38:03 PM   
Digger-RCU



Posts: 453
Joined: 8/21/2002
From: Hanford, CA, USA
Status: offline 		TGC,
I have not tested the Mecoa head for an 049 or an 061, but I did test the 074 head on my norvels. I compared the performance of this head button with a standard glow plug and compared it to the standard norvel glow-head button.

average performance for my three norvel 074's with the norvel glow head and a 7x3 prop was 16600 Rpm

average performance for the same engines and the same prop with the Mecoa head was 15900 Rpm

I hope this helps.

Digger

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RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 8:29:19 PM   
gcb



Posts: 2419
Joined: 10/24/2002
From: Port Ewen, NY, USA
Status: offline 		Frank,

The reason for the RPM loss is because of the increased head volume created by the area around the threads and the area inside the plug. Remember the standard plug seals up at the washer, whereas the Nelson or "turbo" plugs seal at the base.

Factors that you can change that affects performance (and firing timing) for a given engine include prop load (diameter and pitch), fuel, and compression ratio. This plug discussion is about compression ratio. Switching to a standard plug is not unlike adding head shims. If you go this route, you can change some of the other factors to somewhat compensate. I would suggest upping nitro a bit, but try different props also. Since you are not interested in maximum performance, things should be OK.

Using a short plug should have less affect than a long one (I think!). I believe the Tower plug is a 'tweener" so you should be OK with the short adapter.

Cox had a standard plug adapter on their throttled .074...perhaps that's why it was dubbed a dog for performance.

If it doesn't work for you you can still get a Nelson or Turbo adapter.

George

(in reply to franklin_m)
       Post #: 13

RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 11:04:04 PM   
KidEpoxy



Posts: 3386
Joined: 10/14/2004
From: San Antonio, TX, USA
Status: offline 		I have no idea if this will fit, it might hit the piston for all I know...

When using a standard plug, it seats on the shoulder up top. I cant help but think that the Long plug would have more material (more threaded plug body) inside the head than a short. More material in the head would have to give higher compression than having that space empty.

I dont know, it is just concept level.
Like I said, heck, a long plug might poke thru the piston.... and that will clearly lower your compression

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RE: Question - Mecoa Glow Plug Adapters - 6/26/2008 11:51:09 PM   
franklin_m


 

Posts: 125
Joined: 11/17/2005
From: Lemoore, CA, USA
Status: offline 		Everyone, thanks for the input. I guess I'll risk the $10 and give it a shot. I do think the best long term solution is the Nelson head.

Frank

(in reply to KidEpoxy)
       Post #: 15

RE: Question - Mecoa Glow Plug Adapters - 6/27/2008 12:20:28 AM   
Walther


 

Posts: 130
Joined: 8/14/2007
From: Waseca, MN, USA
Status: offline 		Go with the turbo head and you can't go wrong.

(in reply to franklin_m)