Can't get spark in old GTO

I’ve seen a few older point type distributors ground out from deteriorated wire insulation where it enters the bottom of the distributor housing. This kind of falls into the category mentioned by Tester.

In one case the engine would start and run fine but if nailed hard the advance plate moved enough to drag the bare wire against the dist. housing and the engine would start coughing and backfiring.

What a predicament to be in; wrestling an older genuine muscle car. My sister had a 64 GTO and a good friend had a 65 Tri-Power; the latter getting the Posi rear end blown up when he hit 3rd too hard after goading me into a street race.
If I remember correctly my sister sold that 64 back in the late 70s for 300 dollars; straight, red on red, auto w/factory air, and a strong running 389. How things have changed. :frowning:

Dang Ok4450. It’s too bad you didn’t purchase that car back then. It reminds me of a time I could have purchased a custom ordered blonde, birds eye maple, Gibson Super 400 guitar from a friend of mine for 800 dollars back in the early seventies. Unfortunately that was small fortune to me back then. To this day I still kick myself for not trying harder to get it. You’re right-how things have changed.

I still kick myself for passing up on my friends Grandfathers White MGA…(1959 0r 62’ I think?) wire wheels and a Supercharger in a cardboard box in the trunk… FOR $400 …It was covered under a carport for many many years but was running at time of sale…I was there when the new owners were picking the car up…I cried that night…I WAIL AND MOAN…occaisonally present day… I still hve dreams that I actually DID buy it and that it is in my garage …but it isnt… WHat an idiot…But I was broke back then…the $400 might as well have been 10,000…I didnt have either.

SO ZONKER…are you going to tell us whats goin on after all of this great advice? Whats the deal man…

Thanks for all the wisdom guys. I did finally track down the gremlin…and it was me I think. Attached via ring terminal to one of the mounting screws for the points is a small, uncoated woven-wire ground strap. This needs some slack to allow the distributor plate to move with the vacuum advance. The slack in this case had looped upward where it contacted the movable arm of the points, creating a full-time short to ground. After reinstalling the points, she fired up almost immediately.

There may have been another problem in the system originally. Now the’64 seems to have no spark. On with the hunt!

Do yourself a BIG favor and convert both of them to electronic ignition…My favorite was simply installing a GM HEI distributor, used 1975-1981…

Did you do the simple…rotor inside the cap trick, see if its the right rotor…but before that did you verify that there is no spark right out of the coil? If there is spark at coil then we got it made…but methinks there is not… Confirm?

This system is pretty simple… you need a good set of points…a good condenser…a good coil…proper wiring to said coil and you gets sparks…

Here it is in written form:

The Parts

Ignition Coil: This is the part that makes high voltage, up to 40,000 volts, for the spark plugs from the low voltage that is supplied to it by the battery. The reason an ignition coil works lies in the physical properties of electrical current. When a current flows through a conductor it generates a magnetic field around the conductor. Conversely, when a conductor is moved through a magnetic field, a voltage will be induced in the conductor. The coil takes advantage of these principles of inductance by winding one coil over the top of another around an iron core. The changing voltage in the primary winding serves as the ‘movement’ needed to induce a voltage in the secondary winding. The voltage in either winding is proportional to the number of coils in the inductor; if there are more turns in the secondary, its induced voltage will be higher than the voltage in the primary.

When the points close, current through the coil primary increases from zero to maximum in an exponential manner, rapidly at first, then slowing as the current reaches it’s maximum value. At low engine speeds, the points are closed long enough to allow the current to reach a higher current level. At higher speeds, the points open before the current has time to reach this maximum level. In fact, at very high speeds, the current may not reach a level high enough to provide sufficient spark, and the engine will begin to miss. This current through the coil builds a magnetic field around the coil. When the points open, the current through the coil is disrupted, and the field collapses. The collapsing field tries to maintain the current through the coil. Without the Condenser, the voltage will rise to a very high value at the points, and arcing will occur.

Points: Ignition points are a set of electrical contacts that switch the coil on and off at the proper time. The points are opened and closed by the mechanical action of the distributor shaft lobes pushing on them. The points have a tough job, switching up to eight amps of current many times per second at highway speed. Indeed, as engine speed increases the efficiency of your ignition system decreases, thanks to heating problems and fundamental electrical laws. This declining efficiency has a serious effect on your spark voltage and results in poor high-speed performance, incomplete combustion and other drivability problems.

Condenser: Those same principles of inductance create a kind of paradox, because when the points open and the magnetic field collapses it also induces a current in the primary as well. It’s not very much because there are only a few windings in the primary, but it’s enough to jump a small air-gap, such as the one between the just-opening points in the distributor. That tiny spark is enough to erode metal away from the points and you’ll ‘burn’ the points. It prevents the points from arcing and prevents coil insulation breakdown by limiting the rate of voltage rise at the points.

Ballast Resistor: This is an electrical resistor that is switched in and out of the supply voltage to the ignition coil. The ballast resistor lowers voltage after the engine is started to reduce wear on ignition components. It also makes the engine much easier to start by effectively doubling the voltage provided to the ignition coil when the engine is being cranked. Not all car manufacturers used a ballast resistor in their ignition systems So you should check to see if yours does.

HB, you are one of the very few people that I know that gets this right, especially about the condenser. The only exception I have is with this statement "Without the Condenser, the voltage will rise to a very high value at the points, and arcing will occur. ". I think that it is with the wording more than the concept though.

Most people think of the coil as a transformer with a primary and a secondary winding, and in a way, they are correct, but that is more correct with coils used in electronic ignitions that with the Kettering ignition. In the Kettering ignition, the primary and secondary coils were connected more like a tapped choke than an autotransformer. That is, the primary and secondary were connected in series instead of parallel. This effectively made the two coils act like a voltage divider during discharge.

What the coil did not do was step up the voltage like a transformer. It generated the high voltage the same way a choke coil does. Most people look at the step up formula as Vout=Vin (# turns pri/# turns sec). There is a lot more to this formula, but in a simple ac transformer, all the other factors null out.

In the ignition system, timing plays an important part in that the voltage out is also determined by the secondary circuit resistance and discharge time. Thats what generates the high voltage. The voltage at the primary is a fraction of the total voltage based on the ratio of the primary/secondary windings.

The condenser bleeds off the leading edge of this pulse so it doesn’t arc across the points while they are just barely open. With or without the condenser, the voltage will rise to between 150 and 250 volts depending on RPM (15-25kV spark). Its just that the points will not feel the full voltage at the moment the points open, the condenser is absorbing the leading edge of the pulse.

New points have to be filed just enough to scratch them a little. If you don’t do it, they have a habit of not working at all or they will fail after it rains the first week. The best way to file them is before they are installed. Yes, you can use 200 grit sandpaper and pull it through twice but do it outside of the distributor. Don’t do it with people watching or they might throw a fit.