Hello, I have a 305 with an accel hei with vacuum advance, no ecu. This thing has been the most frustrating and problematic ignition I've ever encountered..
For a while, the thing would blow coils and modules left and right. Get a new one, fire it up, and it would shortly fry in less than 2 hours run time. I've been through 8 each now.
Said screw it, got a new coil, module, plugs, rotor, condenser and pickup coil as of today, all Borg warner parts. Still no spark what so ever.
Yesterday it fired up, I backed the car out, and suddenly no spark.
I checked the system and what I found was getting 12-12.5v at the coil, coil was reading infinite resistance so I got another pickup coil, and still no spark.

My system is setup like this
Hot wire from battery to dip switch, switch to 20a fuse, fuse to batt terminal at coil. Ground strap in the cap is there and clean, and the ground wire on the coil is bolted securely.
All my wires are intact/not broken and such, all connections are tight, and the fuse has never blown.

As of now, I don't know what else to do..unless one of the parts was bad out of the box, I can't see any reason why I'd get no spark and why it would keep blowing coils and modules like this.
if anyone has any ideas, I'd much appreciate em.
Thanks

 

Ohm reading on new pickup coil is 718, infinite secondary and primary on ignition coil, and infinite from dist. Body to motor. So I have a good ground, pickup coil is good, ignition coil (brand new..) is shot. I noticed when cranking, the voltage going to the coil drops to 9v. I'm going to put a smaller gauge wire in to see if that helps; would low voltage cause coils to keep blowing?

 

New ignition coil and it fired right up, though I'm still drawing 9v when cranking, 12.3 regularly.

 

My car was setup exactly like yours was when I bought it. 305 H.O engine, no ECM/ECU, vacuum advance accel distributor, battery to a switch in the dash, from that switch right to the battery terminal on the coil. I never had a problem with my coil frying. It would always run fairly well, except for the vacuum advance being screwy. Sorry I can't offer much help to your situation, just giving my experience with the same setup, aside from using a fuse inline. Hope you can get everything sorted out.

 

So if you were running that setup, it should be a decent setup to use then.
Damned thing..

 

Is the voltage regulator on your alternator OK? I was wondering if you are frying stuff from the voltage being too high.

 

Yes, I'm drawing 12.2v regularly, 9.3 when cranking and back to 11.7 running

 

Just got her running again, voltage at the alternator was 14.7, could that be the issue? My alternator is from a 78 caprice, dunno if those are internally or externally regulated

 

That seems a little high to me. I measured mine and it is about the same as yours and I suffer blown bulbs quite a bit. My other cars seem to run at about the high 13s. I'm not sure if this is your problem or not, it is more likely spikes that cause electronics to fail but it might pay to get it checked if you can't do it yourself.

 

My alternator checks out as good, and its not spiking. Just stays in the 14s consistently, fluctuating a tenth or so at most. I'm thinking my next step would to get a alternator for this car/internally regulated.

 

The kind of spikes I'm talking about you probably can't see on a voltmeter you need a scope.