049 Glow plug conversion perfected
04-09-2003, 08:36 PM
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049 Glow plug conversion perfected
Well folks here it is. After many hours of hard work and testing I am proud to present my 049 head that has been modified to accept glow plugs. Enjoy!!!
04-09-2003, 11:52 PM
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049 Glow plug conversion perfected
As you all know its a tee dee. Im using a traxxas long glow plug but im probably going to switch to an os which is a hotter plug.the fuel im using is homemade 15% nitro with 25% all castor oil. I also have a kustom kraft fine thread needle on it with a crankcase tap for the fuel tank. I using an APC 5.5x4 prop and im getting 15800 rpm with this set but it was cold outside when we were testing it so we are waiting for warmer weather tommorow to run it up again. I am also going to get some 25% nitro fuel and get a measurement there as well with a 5x3 prop if I can find one locally. Compression is a little lower due to the hole in the glow plug for the element is larger than the original hole in the stock glow plug. We ran it without any head shims and got 16200 on the same set up.This is a standard compression head and i also have a tee dee(2 fin head) that I would like to modify as well.The traxxas plug was not selected on purpose, it was just because i had one. Thats why im going to go for the hotter os plug. I will post new answers after furhter tests this weekend.
04-10-2003, 07:32 PM
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049 Glow plug conversion perfected
Well we ran it up today in some warmer weather and we got maxed out at 16.5k. I adjusted the compression by shaving the flange at the base of the head. Works great now. look fo them on ebay soon.
04-10-2003, 09:29 PM
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049 Glow plug conversion perfected
I believe you are right I just got ahead of myself. Okay folks its 20.00 for one of mine but if you send me yours I will do it for 12.00 plus first class shipping with delivery confirmation.
04-11-2003, 12:10 AM
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049 Glow plug conversion perfected
PCarroll,
Are you aware that RJL makes heads to fit COX 049/051? They are available two variations for use with long or short plugs.
http://www.mecoa.com/acc.htm
Are you aware that RJL makes heads to fit COX 049/051? They are available two variations for use with long or short plugs.
http://www.mecoa.com/acc.htm
04-11-2003, 02:18 PM
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049 Glow plug conversion perfected
Pcarroll,
I have both of the RJL heads and I will post a picture tonight when I get home.
Actually, there are at least 2 other sources of these items. Another one I have is from an outfit that I believe is called Charlie's R/C - don't know if they are still in business or not. I will include this one in the picture.
Another source is Norvel. You would need to get their head to use this - total cost is about $9. See:
http://www.shopatron.com/product.pht...t_id=NVL100148
I have both of the RJL heads and I will post a picture tonight when I get home.
Actually, there are at least 2 other sources of these items. Another one I have is from an outfit that I believe is called Charlie's R/C - don't know if they are still in business or not. I will include this one in the picture.
Another source is Norvel. You would need to get their head to use this - total cost is about $9. See:
http://www.shopatron.com/product.pht...t_id=NVL100148
04-11-2003, 11:26 PM
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049 Glow plug conversion perfected
pcarroll,
Here is a pic of the glo heads that I mentioned earlier. The red on on the left takes long plugs while the purple on takes short ones. The silver one in front is the one I believe to have been made by Charlie's R/C - it takes short plugs.
Here is a pic of the glo heads that I mentioned earlier. The red on on the left takes long plugs while the purple on takes short ones. The silver one in front is the one I believe to have been made by Charlie's R/C - it takes short plugs.
04-12-2003, 12:19 AM
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049 Glow plug conversion perfected
Darn it! Darn it! Darn it!!!! What kind of rpm are you getting out of them versus a stock plug? It ifgures that i thought i had a great idea and someone already beat me to it
04-12-2003, 01:44 AM
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049 Glow plug conversion perfected
These heads do suffer from a significant reduction in power - probably to the larger size of the combustion chamber thereby reducing the compression ratio. If you follow the link to the Norvel website, they claim a loss of 20% power compared to the standard head. Your solution probably works better than these in the power department.
04-12-2003, 03:00 AM
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049 Glow plug conversion perfected
Don't be discouraged. Try this on the next one you make. Using a taper tap, don't run the tap all the way through. Let some of the taper make a very tight fit for the glow plug. In other words, a tapered thread. Make it so that it takes a lot of effort to screw the plug down using two wrenches. Dress up the plug with a die to help out.
Combustion chamber volume is a problem, as suggested. The other problem is that, believe it or not, the gap in the threads is part of the combustion chamber. You want to seal this gap as much as possible. You might pick up substantial RPM this way. The other thing to try as an experiment is to use blue Loktite in the plug threads in the head you've already made. This will seal the threads but still make the plug removable if needed, in which case, you'll have to heat it carefully with a torch.
On the same engine and prop, try a Cox plug, your current design and then another with the tapered/sealed threads.
Let us know how they compare.
Combustion chamber volume is a problem, as suggested. The other problem is that, believe it or not, the gap in the threads is part of the combustion chamber. You want to seal this gap as much as possible. You might pick up substantial RPM this way. The other thing to try as an experiment is to use blue Loktite in the plug threads in the head you've already made. This will seal the threads but still make the plug removable if needed, in which case, you'll have to heat it carefully with a torch.
On the same engine and prop, try a Cox plug, your current design and then another with the tapered/sealed threads.
Let us know how they compare.
04-12-2003, 09:17 PM
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049 Glow plug conversion perfected
On a stock head we were getting 17k on 15% fuel with 25% oil. I was getting 16.5 - 16.8k with the head i mad with little loss in power. Im sure if i used a 2 fin head or even a 1 fin head i could really make it scream.
04-12-2003, 10:08 PM
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049 Glow plug conversion perfected
pcarrol,
Those are excellent numbers from your head. AFAIK, the other heads all lose 15-20% power (probably why they have never been popular). You might still be on to something here. Keep it up!
Those are excellent numbers from your head. AFAIK, the other heads all lose 15-20% power (probably why they have never been popular). You might still be on to something here. Keep it up!
04-12-2003, 11:00 PM
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049 Glow plug conversion perfected
Charlie's R/C used to make conversion heads for the .049/.052 & the .099 they were sold through ACE R/C , went the way of the DODO bird. You might look in to making them for the COX .15 as I don't think any heads for them are available for a regular plug.
>>>>>>>>>>>>>>>big max 1935>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>big max 1935>>>>>>>>>>>>>>>>>
04-13-2003, 06:13 AM
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049 Glow plug conversion perfected
By the sound of it, you have a superior head to all the others. It could be that you've hit the magic number for the compression chamber volume. Good work.
04-13-2003, 12:40 PM
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049 Glow plug conversion perfected
Anyone read the last issue of FM (Randy's column, small steps) just happened to have an article on glow head conversions and why one fellow thinks they loose power.
It seems the compression volume is NOT the issue, but the small, seemingly insignificatnt gap between the glowplug and insert threads. When Henry Nelson did an experiment and made the threads very tight at the bottom, there was not nearly as much loss (they were using a 15 engine, same effect).
I myself have made some conversion heads - with a lathe and a 1/4-32 tap its quite simple, but I want to experiment with making the threads very tight at the bottom and see what happens. If you have a taper or plug tap its easy, just dont cut the threads to full depth at the bottom of the insert.
Also, I was thinking of trying one where I actually "glue" the glowplug into the head with the high temp aluminum stuff I have, and allthough it is a one shot deal, just to see if it delivers more power. I have lots of burnt out glowheads to experiment with!
Andrew
It seems the compression volume is NOT the issue, but the small, seemingly insignificatnt gap between the glowplug and insert threads. When Henry Nelson did an experiment and made the threads very tight at the bottom, there was not nearly as much loss (they were using a 15 engine, same effect).
I myself have made some conversion heads - with a lathe and a 1/4-32 tap its quite simple, but I want to experiment with making the threads very tight at the bottom and see what happens. If you have a taper or plug tap its easy, just dont cut the threads to full depth at the bottom of the insert.
Also, I was thinking of trying one where I actually "glue" the glowplug into the head with the high temp aluminum stuff I have, and allthough it is a one shot deal, just to see if it delivers more power. I have lots of burnt out glowheads to experiment with!
Andrew