Rev counter wiring question

R

redhouse53

Member
I'm putting the final touches to a 3500 P6. When we came to fire it up, it wouldn't fire until we took the rev counter wire off the coil, then it fired up straight away? We had the rev counter connected to the negative side of the coil, is this right? Any ideas?
 
Hi redhouse,

Simple fix- the rev counter should be fitted to the +ve side of the coil. The negative side should only be wired to the low tension block on the dizzy, as the switch (contact breakers) are on this side. At the moment, the contact breakers are being bypassed, as when they open, the coil continues to be connected to the negative through the rev counter (which is earthed through the dashboard circuit board). If the coil is not momentarily 'switched off', the charge in the outer coil will not transfer to the inner coil, and hence no spark. The rev counter operates on a digital-to-analogue principle, by effectively translating the frequency of electrical pulses across the coil (caused by the points opening and closing) into an analogue read-out through some sort of precision solenoid/coil arrangement.

Swap it over and see what's what.
Michael
 
It's worth checking everything over then. Make sure the dizzy lead is definitely connected to the -ve. I can't be sure, but I imagine the coil would still work for a short time if it was wired up backwards (ie dizzy to +ve), which would allow you to start it up, but could cause expensive trouble if left that way! Always best to make sure I suppose!
 
redrover said:
I can't be sure, but I imagine the coil would still work for a short time if it was wired up backwards (ie dizzy to +ve), which would allow you to start it up, but could cause expensive trouble if left that way!
Click to expand...

It will work if wired the wrong way, but it erodes the plug earth electrode, rather than the centre one, which can mean in time the earth electrode gets so thin a bit can fall off. I've seen them eroded, but can't remember seeing one where the end has dropped off completely though.
 
Thanks, the dizzy is deffinately on the -ive side, so it's all good there. I think this one is just schoolboy error!
 
...if only my errors were schoolboy ones! I tend to be very careful and fastidious with the small, easy, cheap-to-replace things, and hit the big, expensive, breakable things with hammers!! :?
 
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