Duraspark II Conversion - How To
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
The positive side should have about 7 volts in Run and 12 in Start. There's a ballast resistor that is meant to drop it like that.
If you have spark, then are you getting it at the appropriate time? Put a timing light on it.
If you have spark, then are you getting it at the appropriate time? Put a timing light on it.
New User
Joined: Dec 2014
Posts: 10
Likes: 0
From: Urbana, OH
The truck just ran good this morning with the old ignition while I played with the new carb to get it set up. Just double checked the timing & it should be good. Installed distributor to No. 1 TDC compression stroke. I knew about the resistor wire but I'm confused how I can get 12v with the coil unplugged and 7v plugged in. And I just discovered that I get 12v with the coil plugged in as long as the distributor is unplugged. Strange if you ask me.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
When there's no current there is no voltage drop across a resistor. So, when the coil unplugged there's nothing pulling current and the voltage will go to 12v. And, probably when the dizzy is unplugged the module doesn't ground the coil so you also get 12v.
More Turbo
Joined: Jan 2014
Posts: 531
Likes: 1
The truck just ran good this morning with the old ignition while I played with the new carb to get it set up. Just double checked the timing & it should be good. Installed distributor to No. 1 TDC compression stroke. I knew about the resistor wire but I'm confused how I can get 12v with the coil unplugged and 7v plugged in. And I just discovered that I get 12v with the coil plugged in as long as the distributor is unplugged. Strange if you ask me.
Cargo Master
Joined: Mar 2008
Posts: 2,589
Likes: 212
From: Washington
This test shows up best if using a 12 volt test light , connected between coil neg and GRD. The test light should flash while cranking. The 12 volt pulse is to fast for many DVM.
New User
Joined: Dec 2014
Posts: 10
Likes: 0
From: Urbana, OH
That makes complete sense now Gary, I should have known that!
And Sean, reading up on the swap it seemed to be a simple plug & play job lol. I got a new module (with blue grommet) and distributor, both for an '80 or '81 I believe
And Sean, reading up on the swap it seemed to be a simple plug & play job lol. I got a new module (with blue grommet) and distributor, both for an '80 or '81 I believe
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
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Cargo Master
Joined: Mar 2008
Posts: 2,589
Likes: 212
From: Washington
Thanks, and BTW not only was your explanation of the "no current - no voltage drop" perfect ... it was done in under two lines.
I would have rambled on for two paragraphs
Jim
I would have rambled on for two paragraphs
Jim
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
New User
Joined: Dec 2014
Posts: 10
Likes: 0
From: Urbana, OH
It was a lot of work. I just had to dissect the '78 harness and track down my coil power wire to splice into the '78 harness and use my original water temp & oil pressure wires.
I did finally get it to fire! Had to play with timing & carb but it only hits off the starter and only when I hold it wide open throttle so back to some carb tuning now
I did finally get it to fire! Had to play with timing & carb but it only hits off the starter and only when I hold it wide open throttle so back to some carb tuning now
