As the title suggests, my challenge of the week is trying to work out a simple and hopefully cheap solution to the issue of connecting the factory dash gauge tacho to the multi coils set up.
My set up has 4 coiled ganged together in pairs to make a twin wasted spark version.
The coils are plain old bosh ones driven by a bosh module, so nothing fancy like COP.
I believe the tacho is a neg driven one, and when i connected the signal wire to one of the coils it works fine, but at half speed of course.
I didn't try and connect the neg of both banks figuring I'd create crosstalk by doing so.
I know one solution would be be to go down to the second hand boat shop and buy an outboard motor tacho designed for 2 cyl motors and simply wire that up to half the cols (one bank), but that means gutting the dash and the dash is quite sexy as it is, so this will be the last option I explore when all others have failed.
A net search details a few different circuits with diodes and resisters but there is enough variation in their designs to confuse the heck out of me.
Does anyone here have any clear advice (for dummies) for getting around the problem???