Forget the fuel pump and filter. The pump just keeps the float bowl filled to the correct level. If that level drops from where it should be, the mixture will be too lean. That can cause surging, but it has to be pretty bad before you will notice that. More importantly, it can take five to ten seconds of no fuel flow from the pump before the level in the float bowl gets that low, and it would not refill right away when the flow did resume. You would have a symptom that lasted a good five to fifteen seconds, not just a little glitch or hiccup.
For the fuel filter, your model is a little before my time, but since Chrysler used the 2"-diameter plastic filter, all the way to today, you will not solve a running problem by replacing them, (except for diesel engines). Those filters easily last the life of the car. There is a pick-up screen on the tube in the gas tank that collects most of the junk. When it becomes clogged, or when it collapses, the symptoms are quite different. If that screen was not used on a 1964 model, then you will need to replace the fuel filter periodically, but it will not cause what you described.
To have a symptom that lasts so briefly, I'd be looking at the ignition system, and I would start with the basics. Worn bushings in the distributor will let the shaft wobble. A stretched timing chain will allow camshaft timing to vary, and since the camshaft drives the distributor, either of those will cause ignition timing to wander around. You can see that with a timing light. Typically those would not be related to road speed, but for a test, see if the problem occurs at around forty to forty five mph in second gear. That will put the engine at about the same speed as in third gear at seventy mph.
For the basics, mist some water on the spark plug wires while the engine is running. Do that in a dark area, and you will often see lightning around the wires. If the spark jumps alongside a spark plug, it will have bypassed the gap and you would have a single misfire. Also, look for carbon-tracking inside the distributor cap, and on the outside. Mist the cap with water too. The ignition coil can be breaking down inside where you may not see arcing, but that usually progresses real fast to a crank/no-start condition. A better suspect would be an ignition coil that is capable of developing a spark voltage of, lets say, 15,000 volts. It will always have some reserve if the plugs require 14,500 volts for the spark to jump the gap, but if one takes 15,001 volts occasionally, due to a lean mixture or worn electrodes, that will cause a misfire.
Also do not overlook the carbon-impregnated string in the spark plug wire burning away under the boot. When that gets real bad, the boot will be hard and crunchy, and will crumble when you squeeze it. Before it gets that bad, you have to look real close inside at the terminal and that string.
There is going to be a ceramic ballast resistor near the ignition coil. The terminals on it are not insulated against moisture. Shine the terminals on the resistor with sandpaper if they are rusty. There is no good way to clean the terminals on the wires. Better to snip them off and replace them if they are rusty.
When you replace the breaker points, change the condenser too. We often ignore that because they do not cause a lot of trouble, but it is providing the ground for the coil's secondary winding. A weak or open condenser will cause weak spark.
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Wednesday, September 20th, 2017 AT 9:42 PM
