Looking for some old school Electrical Ignition help.. (ie pre-computer controlled stuff).. Working on a small twin cylinder 4 cycle engine that used the "Waste Spark" setup for the ignition (where both cylinders fired every time whether it was exhaust or compression stroke). I think the coil pack thats on the engines gone as itll run for 2 minutes and die.. you can smell its getting gas.. if you let it sit for an hr.. itll fire up again and do it all over again...

Bad thing is the mfg discontinued the coil and now they want 2 arms and a leg for the replacement... which i dont feel like paying that much for.. So was trying to figure our how to make something else work for less. the thought came to mind of going old school and wiring 2 canister coils together to serv the same purpose.. the downside is i wont be able to use their ignition module either.. having to work around it too (in other words removing it for my own)..

Excuse my crude electrical drawing.. im not a Picasso...



So was wondering if this would work for getting both coils to fire at the same time? this diagrams showing them wired in series.. but was also thinking about wiring them in paralleled.. but not sure which would work better for what i need it to do..

 

I am thinking the HEI module is not going to fire two coils at once, that is too much load for it.

I wonder if you could use one coil and put two spark plugs on it?

Or use two HEI modules, trigger both and each one would have it's own coil to drive. make sure to mount them to a large piece of aluminum for cooling. They get hot and that's why I am saying it may not drive two coils.

 

I don't think the series design will work.

The paralleled idea should work in theory, but you would need matched coils with primary resistances greater than 1.4 ohms. Two 1.4 ohms coils would be .7 ohms in parallel. But this still might be to much load for one module.

The dual coils with dual module is the safest idea and you could use unmatched coils and the same trip / pulse signal for both modules.

If you put 2 plugs on one coil the plug with the smaller gap will spark and not the other plug.

Jim