If your classic car is coughing or refusing to start, learning how to set points on distributor systems is probably the first thing you should check. There is something really satisfying about working on an older engine. You don't need a fancy laptop or a degree in computer science to get it running right; you just need a few basic tools and a bit of patience. While electronic ignition has mostly taken over the world, those of us who love vintage iron know that a well-set pair of points can make an engine purr just as sweet as anything coming off a modern assembly line.
Getting Your Tools Ready
Before you dive under the hood, you're going to need a handful of things. This isn't a complex job, but having the right gear makes it a lot less frustrating. You'll definitely need a flathead screwdriver—maybe a Phillips too, depending on your specific car—and a set of feeler gauges. If you've never used feeler gauges before, they're just thin strips of metal of varying thicknesses used to measure tiny gaps.
You might also want a remote starter switch if you're working alone, or a buddy who can sit in the driver's seat and "bump" the engine for you. Oh, and a little bit of distributor cam grease is a lifesaver. Without that tiny dab of lube, the little plastic rubbing block on your points will wear down faster than you'd believe, and you'll be right back here doing this all over again in a month.
Opening Up the Distributor
First things first, you've got to get to the points. They live under the distributor cap, which is usually held on by a couple of metal clips or screws. Pop those off and lift the cap. You don't necessarily have to take all the spark plug wires off, but it makes things easier if you do. Just make sure you mark them or take a photo first so you know exactly where they go back. There's nothing worse than finishing a job only to realize you've messed up the firing order and the car sounds like a tractor.
Once the cap is off, you'll see the rotor. That's the spinning piece on top. Pull that straight up and off, and there they are: the points. They look like a little set of spring-loaded jaws. Their whole job is to open and close as the engine spins, breaking the electrical circuit to fire the coil.
Finding the High Point on the Cam
This is the part that trips people up. You can't just measure the gap at any random time. You need to rotate the engine until the rubbing block of the points is sitting right on the highest point of one of the distributor cam lobes. The cam is that bumpy, multi-sided shaft in the middle of the distributor.
To do this, you can use a socket on the crankshaft bolt to turn the engine by hand, or you can "bump" the starter. If you're bumping the starter, just do it in tiny increments. You're looking for that moment when the points are pushed as far apart as they'll go. Once you're on the peak of that lobe, you're ready to measure.
Measuring and Adjusting the Gap
Now, grab your feeler gauge. You'll need to check your shop manual for the specific "gap" your engine requires. For many old V8s, it's somewhere around .016 or .019 inches, but don't guess—look it up. Slide the correct gauge between the two metal contacts on the points.
What you're looking for is a "light drag." It shouldn't just fall through the gap, but you shouldn't have to force it either. It's a bit like pulling a blade of grass through your fingers. If the gap is wrong, look for the adjustment screw. Loosen it just enough so you can move the points assembly back and forth.
Pro tip: Most distributors have a little notch where you can stick your screwdriver to pry the points open or closed with a lot of precision. Once the gap feels perfect with the feeler gauge in there, tighten that screw back down. Then—and this is important—measure it again. Often, the act of tightening the screw will shift the points just enough to throw the gap off.
The Difference Between Gap and Dwell
If you want to be really precise about how to set points on distributor setups, you'll eventually hear about "dwell." While setting the gap with a feeler gauge gets you in the ballpark, dwell is a measure of how long the points stay closed while the distributor is spinning.
If you have a dwell meter, you can check this while the engine is actually running. On some old GM cars, they even had a little "window" in the distributor cap so you could stick an Allen wrench in there and adjust the points while the car was idling. It's incredibly convenient. For most other cars, though, a good feeler gauge adjustment is usually plenty to get you back on the road and running smooth.
Checking the Condenser
While you're in there messing with the points, it's usually a good idea to look at the condenser. It's that little metal cylinder sitting next to the points. Its job is to act like a shock absorber for the electricity so the points don't "arc" and burn up too fast.
If your points look all pitted or have a weird mountain-and-valley shape burned into the metal contacts, your condenser might be shot. They're cheap, so if you're already doing the work, most folks just swap them out as a pair. It's cheap insurance against a breakdown.
Finishing Up and Testing
Once you're happy with the gap and everything is tightened down, put the rotor back on. It usually only goes on one way, thanks to a little notch. Snap the distributor cap back into place, hook up your wires if you took them off, and give it a shot.
If you did it right, the engine should fire right up. You'll probably notice it idles a lot smoother and has better throttle response. If it won't start at all, don't panic. You might have set the gap too wide, or maybe you accidentally grounded out the little wire that leads to the points. Take the cap back off, double-check your work, and try again.
Common Mistakes to Avoid
One of the biggest mistakes people make when learning how to set points on distributor units is forgetting to clean the points. New points often come with a thin film of oil on the contacts to keep them from rusting in the box. If you don't wipe that off with a bit of clean rag or some carb cleaner, that oil will burn the second you start the car, and you'll have a bad connection.
Another classic error is not checking the timing afterward. Changing the point gap actually changes the ignition timing. If you widen the gap, you're advancing the timing; if you close it, you're retarding it. It's always a good idea to break out the timing light once the points are set just to make sure everything is still lined up where it needs to be.
Why Does This Still Matter?
You might wonder why anyone still bothers with this when you can just buy an electronic conversion kit. There's a certain pride in knowing how to maintain a mechanical system. If an electronic module fails, you're stuck on the side of the road waiting for a tow truck. If your points get dirty or out of adjustment, you can usually fix them with a screwdriver and a piece of sandpaper in a gas station parking lot.
It's about that connection to the machine. Taking the time to understand the rhythm of the engine—how the cam spins, how the points trigger the spark—makes you a better mechanic and a more informed owner. Plus, there is nothing quite like the sound of an old engine clicking back into a perfect idle after a quick tune-up. It makes all that time spent hunched over the fender well worth it.