Re: Ignition Module Testing/Specs
"""""""Around 8 volts to the positive side of the ignition coil.
Key in the 'Crank' (solenoid kicked in) 12 volts at the module 'White' wire."""""""
JYG - aren't you thinking Ford? That's a hard habit to get out of!
I think he said HEI, then he tried the Ford Module.
If it's HEI there should be 12 volts at the coil (+) - "IF" he's eliminated the ignition resistor like he should have.
If not, then the 8 volts.
White bypass wire - should no longer be there for HEI - Hmmm, wonder if it still is and is touching ground somewhere?
Key on, not cranking - when the module first gets power it essentially grounds the coil (-) (Tach Terminal) But in a few milliseconds the current limiter works, so the voltage at the (-) side of the coil will read 6-8 volts (It's in the idle mode, coil's charged, waiting to be released.)
Cranking it will drop a bit lower, depending on the meter used. It's "average" will read lower, or it will be bouncing between 8 and 0. Better to use a dwell meter - it should show about 10-12 degrees dwell at cranking.
If the above is OK -
Look very closely at the ends of the coil - the squared coils are better - higher output, but they tend to break down easier too. Look for any signs of grey or brown streaking - the colors of smoke - that indicates the coil's insulation is breaking down. The only cure is a new coil.
I'm not conviced and don't understand why coils break down from a bad engine/head ground, but if JYG has had experience with it, then do it. It cannot hurt, but if it helps it's good to do.
JYG - if the engine ground was bad, then wouldn't the starter be in trouble too?
If it was the head isn't grounded good to the block, then the spark plug current has trouble returning, (hard to think all those head bolts don't ground well). But usually the coil is mounted on the block anyway. (Or were those you've seen with that trouble had the coil mounted on the heads?)
The path the "secondary" has to take is through the plug, through the head, through the block, through the battery (-) to (+), then through the ignition switch back to the coil primary - where the bottom of the secondary is tied to the coil (+) terminal. A complicated route for sure! Tying the secondary back to the primary like that creates an "Autotransformer" or "flyback" - boosting the output.
I'm not challenging nor doubting, just wondering about the how and why behind it. You aren't the first place I've heard it, so you aren't alone.
Hmmm, wondering too - some battery (-) "ground wires run to the head to a handy bolt, but some run to a manifold bolt, some even go to a handy bolt on the block. I'm wondering if there's some kind of a relationship there too?