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Showing results for tags 'unexpected advantage !'.
At the weekend, I gave the engine a quick spray with the degreaser, left it a few minutes, then hosed it down. Normally the engine starts up straight after this, as I am careful where I direct the hose nozzle. Anyway, this time it didn't start, so off I go looking for the issue. Turned out in the end, to be water inside a supposedly "sealed" standard 30A automotive relay, I use to supply power to my high energy ignition coil, so the higher amperes, don't run through the ignition switch. Anyway, replaced relay coil, & located it a bit higher up in the engine bay. However, while checking things ignition, I lifted the dizzy cap, to see any water had ingress'd in there. Imagine my surprise, when i discovered there was no carbon button poking out of the centre of the cap. Well there was, but there was not much left of it. The Bakelite around the hole where the carbon sits was all broken away, as seen above. Normally, a fault like this would cause all sorts of problems, but my engine had been working perfectly. It then struck me, that because I have a hi-energy ignition coil capable of probably 40-50 Kilovolts; that when the carbon button worn down, it just continued to jump the small gap, & then eat the carbon button away. The gap between the top of the rotor button, & what's left of the carbon button, is around 4-5mm. I had another 3K Denso dizzy cap, so grabbed it, & swapped it over. Was just about to throw this above cap in the rubbish bin, when I had an idea. If it will jump a gap that big, in atmospheric pressure, then why do I need a carbon button at all. The cap was not reusable, because the centre hole was so broken away. What if I put a solid metal rod down there that finished flush with the end of the hole. A quarter inch gutter bolt was just the right size. It was just a little too big in diameter, that it screwed nicely into the Bakelite dizzy cap. I then filed the thread end of the screw, so that when it touched the metal in the cap, at the bottom of the hole, the underside of the screw top, was flush with the end of the hole. it was then just a matter of filing the domed head of the screw, so it was clear of the metal on the top of the rotor button. So popped it back on the car; started up first pop, & took it for a drive, & it worked perfectly. So it's back in the boot now, so if I'm ever caught again with a broken or worn rotor button, I'll just swap the cap over, & be on my way. Reminded me of a story I once heard, that dirt track speed car guys, used to build a gadget with large plastic buttons, spacing the hi-tension leads on the cap, to produce an air gap outside the engine, that created a bigger spark across the spark plugs. Don't know how true the story is, but my little experiment, indicated that you can certainly generate a higher HV out of the coil, if the spark jumps a bigger gap, outside the combustion camber, before it jumps the spark plug gap. Cheers Banjo