I just logged in to add a little something to the 6 pages of our friend with the 58 Chevy, no start. I don't see it now. This seems to be a baffling subject for those who grew up in the electronic/ computer age. Let's just add a few tips for the archives. Forgive me, because I just skimmed through all six pages. Maybe I missed this: The breaker plate moves with the vacuum advance. Therefore, it requires a ground strap. Fords were bad about the braided strap breaking. Chevy had a coated wire I think, but can't remember for sure. Anyway , it needs to be checked, and in one piece. Otherwise, the points won't ground and fire the coil. Also , when working by yourself, all you need to do is turn the engine over until the points are open. Then take your test light pick, and stick it between the open points, with the key on. If all else is right , it'll fire the coil every time. What else?
https://www.jalopyjournal.com/forum/threads/no-spark-from-coil-no-start.1106530/page-6 There it is! It's "only" six (6) pages.
Another possible problem area...I have no idea if it was already covered in the jungle of verbiage. Some GM point plates, perhaps many, pivot Eccentrically for the vac advance. The pivot point is maybe an inch over from the centerline of the shaft, fine if everything is in good shape. As the pivot wears it can reach a position where movement completely shuts down the ignition! Easiest check is to simply unplug the vac hose and jiggle the plate experimentally. This came on suddenly on my old 6 cylinder Nova...a parked the car, which was running fine, it started fine...but the slightest touch on the gas pedal from what seemed to be a perfect idle shut the engine off suddenly and cleanly. It took me a while to correlate vac curve with timing of the shutdown! Cure would probably be a different distributor, since I doubt that you can buy very many hard parts for these things.
The ground in the points is the key to the entire system. That thread is full of hierarchy breaking trouble shooting methods. I got a screaming deal on old bread truck because the breaker plate ground wire was broken. It sat for 5 years because it wouldn't start. They spent over $1000 across three different attempts to get it going. It took me 7 mins to find the problem including pulling the engine cover. I just shook my head while reading the receipts for diagnosis.
Maybe I should have mentioned a thin screwdriver , as well. All we're doing is creating a ground for the coil (minus) Also should have mentioned that when you remove the ground pick , it fires , not when you insert it.
Points closed (grounded) the coil is building its charge. Points open, the electromagnetic Field collapses and that collapse causes the release of the built charge and then that is the coil's fire.
Read post 14 from this thread. https://www.jalopyjournal.com/forum/threads/no-spark-from-coil-no-start.1106530/
Many many times I hear that the coil is the heart of the ignition system. To me that implies that it is the central most important part, and to me that's wrong. The coil is not inactive but it is inanimate with no moving parts, no adjustments, and no nothing else. They can be tested and even passing the test they still fail. They are either good, going bad, or bad and there's nothing you can do about it. When a coil included in the system that coil is to be considered a radical variable. "Substitute with a known good one" right?!? How do you know a known good one from a non known one,,, because you just took it off a car that's running fine- that's how. Out of the box you can get a good one or one that's going bad or a bad one. But let's humor everyone, ok ok ok the coil is the heart or the ignition system. Now what makes it work?? Who's the Heart's BOSS because that's who you want to talk to when things aren't going the way they are supposed to with an ignition system. What's got full control of this so called heart of the system?
Good question. From experience it may on occasion be the “penis of the system”. Not sure about other folks.
That's a rhetorical question, one designed to make the reader think. Of course it's the points leading the coil. But I like the penis analogy a whole bunch. Sure does fuck some shit up if you let the penis be the boss.
No disrespect to the poster of the original thread, but people were trying to teach how to troubleshoot when the guy needed to be taught how a point ignition system works. Sent from my LG-TP450 using The H.A.M.B. mobile app
Let's see,,, What's all in there Main shaft - cam gear, points cam, bushings Timing plate Mechanical advance unit Vac advance unit Points Condenser Rotor Cap Ground wire
You forgot the coil! /jk Of course it's all done electronically today but it really is a remarkable piece of mechanical engineering. The spark must fire at precisely the correct instant from idle to 5000 RPM and back down again.
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