Gm Hei Swap No Spark

[2sixTZombii]

OK so I just typed a two paragraphs explaining how I got here, then chrome reloaded for no aparrent reason. One thing I don't like about this new format, is that vBulletin used to saved your stuff as you typed it and could recover it should your browser drop. But moving on. Car started running like crap, was trying to figure out why, somewhere along the way spun a rod, threw in a L28. New motor came with a electronic dizzy, which I intended to use but for first start up I used my points unit, since I knew that would at least start my old L26. Now that I had confirmed it ran, I installed the 280 dizzy.

Attached the HEI to a grounded spot. Ran ON 12+ and start 12+ to the + side of the coil and the + coil to B on the module. - on the coil runs to C on the module. Red from the dizzy runs to W on the module, and green runs to G. The module tested good at the parts store. The cap is new, the coil is a good Mallory. Sooo what gives? The coil isn't even sparking. Could the dizzy really be that fried? It looked good when I inspected it. Does anybody know a way to test the dizzy?

[Zed Head]

There should be alternating voltage between red and green as you spin the distributor.  That's what triggers the module.  You won't see much on a meter but you should see some variation.  You can also measure resistance of the pickup coil (green to red wires when disconnected) to see if it's in spec.

 

Is the original module still connected under the dash?  That might keep current flowing on the coil circuit.  Which would keep the coil from sparking.  Not sure why it wouldn't do the same with points but maybe you left the blue wire off for the quick points system test.

 

Also see that you didn't mention the rotor.  People have been known to forget to install it.  I did once.

 

 

Forgot to say - of course, there's a test procedure in the Factory Service Manual.  Engine Electrical chapter, any 280Z FSM.

[EuroDat]

I would also suspect the inductor in the dizzy. Since you don't know the history on the distributor it would be a good place to start. If you have an analoge voltmeter, set it to the lowest volt setting, disconnect the pickup wires, and you should see the meter bouncd when you turn the engine over.

It could also be the module. That can happen and you wont even see a spark. That is why I started with a couple of $10 units to get all the problems worked out when I coverted my 280Z.

http://www.classiczcars.com/topic/49588-fitting-a-hei-module-in-transistor-ignition-unit-1977-280z/

Chas

Edit: added link to my thread

[2sixTZombii]

Yes the rotor was definitely installed. Although I have done that before. My car has always had points in my ownership. It's supposed to have had electronic factory, but its an early 260, so who knows. So it wouldn't be the old module interfering, the only other wire is the tach wire. I had autozone test the module, and passed three times. I'll run some tests tomorrow.

[Zed Head]

74 was the first year of electronic.  The blue tach wire runs to the ignition module.  It's a branched circuit.  Stick your head up by the fuse box and make sure the module is unplugged.  Could be your problem.

[2sixTZombii]

Its really easy to disconnect from the coil, I can do that first.

[Zed Head]

The tachometer will stop working if you do.  But it might work.  The module has a plug, all you have to do is pull.