John Falconer Posted February 13, 2009 Share Posted February 13, 2009 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? Quote Link to comment Share on other sites More sharing options...
Chris Channon Posted February 13, 2009 Share Posted February 13, 2009 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 !!!! Chris Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted February 13, 2009 Share Posted February 13, 2009 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? ken anderson................................................ Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted February 13, 2009 Share Posted February 13, 2009 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. E.D. Quote Link to comment Share on other sites More sharing options...
Mark Lubbock Posted February 17, 2009 Share Posted February 17, 2009 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 Quote Link to comment Share on other sites More sharing options...
John Falconer Posted August 4, 2009 Author Share Posted August 4, 2009 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. Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted August 4, 2009 Share Posted August 4, 2009 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..... Quote Link to comment Share on other sites More sharing options...
Bladerunner Posted August 18, 2009 Share Posted August 18, 2009 Posted by Steve Hargreaves on 04/08/2009 22:02:18: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..... Good point. Thus an excuse to run higher nitro! Quote Link to comment Share on other sites More sharing options...
thomas oliver 1 Posted August 18, 2009 Share Posted August 18, 2009 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. Quote Link to comment Share on other sites More sharing options...
Pat (rActive) Harbord Posted August 18, 2009 Share Posted August 18, 2009 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? Quote Link to comment Share on other sites More sharing options...
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