|John Falconer||13/02/2009 15:39:49|
|11 forum posts|
I have just completed a Sig Hummer 1/2a racer (see picture) but all three glow heads for the Black Widow engine are defunct.
I built the model to make use of this engine and an old 2 channel Futaba radio set that were salvaged from my first model which was a Gentle Lady glider. (It got stuck in a tree, soaked by rain, eventually fell out and was trampled by a herd of cows )
Does anyone know where I can get some replacement glow heads in the UK please?
|Chris Channon||13/02/2009 18:56:00|
|550 forum posts|
Hi, Sussex Model Centre sells them, not cheap , but they are rated at 1.5 volt, if you can use long leads from a 2v cell or turn the glo driver right down on the power panel.
Of course you could use a D type dry cell to energize the plug like we used to !!!!
|ken anderson.||13/02/2009 18:59:23|
8683 forum posts
hello chris-the good old day's with the d cell/cox engine's--we used to think were the bee's knee'ssure i read that someone had drilled out the cox head and tapped for an ordinary glo plug?
|Engine Doctor||13/02/2009 22:30:47|
2511 forum posts
Hi john .You can modify the head to take an ordiary plug but there isn't much material to play with . and you wil probably need an old cox cylinder to hold the head in a lathe so as not to damage the very fine thread. I made one some time ago and it ran ok but I think its worth paying the extra for a proper head.
|Mark Lubbock||17/02/2009 14:06:08|
313 forum posts
|You can tap out the head-you need a 1/4x32tpi tap, a model engineers thread, available naturally from model engineering suppliers. I think a 1/4 UNEF is also around the same. Unless you do a lot, probably not worth it-try Cox Supplies on Ebay-you can get a complete sure start engine for £8.90 from them, cylinders, complete with piston & head & glow heads etc. all at fairly cheap prices. Take care with the volts as described above & a head should last a long time|
|John Falconer||04/08/2009 10:55:12|
|11 forum posts|
Thans for all the suggestions. I have just bought a couple of drilled heads from ebay. Delivered in 2 days by a canadian company. I'll try to do a test flight in the next couple of weeks and post a photo of the results.
|Steve Hargreaves - Moderator||04/08/2009 22:02:18|
6763 forum posts
I'd be interested to see how they go......one of the problems of drilling & tapping the head for a standard plug is a loss of compression ratio (adding the standard plug increases the volume of the combustion chamber thus lowering the effective compression) & this reduces power considerably....lets face it at 0.8cc you don't need much of a change to have a big effect.....
129 forum posts
Good point. Thus an excuse to run higher nitro!
|thomas oliver 1||18/08/2009 22:27:21|
|96 forum posts|
Sorry to disagree with some of the previous info. There is plenty of metal thickness in the head of the Cox. So much so that the head neads counter-boring to bring the plug through level with the inside of the head. Which of course means there will be no loss of compression. How do I know - I have just converted an old head - took about five minutes and looks OK to me. Modolit.
|Pat (rActive) Harbord||18/08/2009 22:40:35|
634 forum posts
|I had a sure start off a Canadien company on ebay. No problems at all, I think they bought up as much of the factory stock as they could when cox stopped producing them a few years ago?|
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