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On 2/7/14 5:46 AM, matty mcqueeney wrote:
Could anybody help me find a reasonable spark gap, that is simple to make?
Thanks Matthew.
The "two bolts on an L-bracket" scheme described by Scott and Carl is a
good first start.. BUT..
Scott's comment about air blowing on it is an essential thing..
The problem I find with a "two bolt gap" is that inevitably, it gets hot
spots which greatly reduce the gap firing voltage, so adjustment is a
pain. A gap that just fires when cold will fire too soon when hot,
reducing the voltage on the caps and reducing spark length.
You'll see this as the coil "losing performance" as you run. It will
also change sound, because as the firing voltage decreases, you get more
sparks/line voltage cycle. And because the charging current/voltage is
sinusoidal, you get interesting chaotic behavior. Cool effect in some
ways, but makes it really hard to know if you're coil is "in tune".. did
the sparks get shorter because I moved the tap too far, or is it because
the gap is getting hot.
I'd seriously look for something larger in diameter that has good
surface area for cooling. (a couple pieces of pipe, or a pair of pipe
couplers, works well)
The other thing that helps is to have a fairly large area with equal gap
distance (sort of the opposite of two needles), because then the sparks
can jump from anywhere, which reduces the heating at one point.