Coils

[Bob Vehring]

Take this for whatever its worth to you, I haven't totally figured it out yet.
I tend to think of a coil as it either works or it doesn't. Last night we were dynoing my V max engine, this is the one with alot of work done to it.
Fired right up, does have alittle brake in time, but not much. I thought it sounded pretty good but noticed some weirdness in EGT readings, one side lagging behind the other in temp, whats really strange it seemed to move from one side to the other. Played around with jetting but didn't really change the problem. Ended up pulling 108 hp which I didn't think was bad. Perry thought it still sounded kinda flat. Without much more there to change, he grabbed a coil off a A/C 440 Champ engine. We had changed wires and plugs, so only the coil was different. Sounded much snappier and HP went up to 112.8
Have to admit, didn't sound bad enough to me that I ever would have thought of trying that

[Vmax540]

I wondered why Cats were so, Fast....
Coils can be open (break in the wire) or shorted out (winding wire has break in insulation and wire touches another loop of wire) and of course you can have a wire shorted to ground. If the open circuit gap is large this will be a no go and the shorted out can be intermittent and usually gets worse as the circuit warms. Interesting find ! People tend to mix up open circuit and shorted circuits so, think of a on/off switch connected to a light bulb and if the switch is open (no light) if shorted the light bulb will be on !