Learning how to set gap on points is one of those old-school skills that every classic car or vintage motorcycle owner eventually has to figure out. If you've got an engine with a distributor and a set of contact points, you already know that when things aren't dialed in, the engine runs like a bucket of bolts—if it runs at all. It's a simple mechanical process, but it requires a bit of patience and a steady hand.
Back in the day, this was just part of a standard Saturday afternoon tune-up. Nowadays, with electronic ignition being the norm, the art of gapping points feels like a bit of a lost craft. But honestly, once you get the hang of it, there's something really satisfying about hearing an engine purr perfectly just because you spent ten minutes with a feeler gauge and a screwdriver.
Why You Still Need to Know This
You might wonder why we still mess with this stuff instead of just throwing an electronic conversion kit at every old engine we find. Well, for one, some people like keeping things original. There's a certain charm to the mechanical simplicity of a points system. But more importantly, the gap on your points directly affects your ignition timing and the strength of your spark.
If the gap is too small, the points don't stay open long enough, which can lead to a weak spark or even cause the points to burn out prematurely. If the gap is too wide, the points don't stay closed long enough to fully charge the ignition coil, leading to misfires at high speeds. It's all about finding that "Goldilocks" zone where the engine is happy.
Tools You'll Need Before You Start
You don't need a massive rolling toolbox for this job. In fact, you probably already have most of this stuff sitting on your workbench.
First and foremost, you need a set of feeler gauges. These are those little metal strips of varying thicknesses that look like a pocketknife. You'll also need a flathead or Phillips screwdriver (depending on the screw holding your points in place).
It's also a good idea to have a ratchet and socket that fits the nut on the front of your crankshaft pulley. This makes it a lot easier to turn the engine over by hand. If you're working on a car with a manual transmission, you could technically just put it in gear and rock the car, but that's the clumsy way to do it.
Finally, grab a clean rag and maybe some contact cleaner or a bit of high-grit sandpaper. If you're working with old points, they might have some oxidation or "pitting" on the surfaces that needs to be cleaned off before you can get an accurate reading.
Getting Down to Business: The Step-by-Step
Before you touch anything, make sure the ignition is off. You don't want to get a surprise zap while your fingers are shoved inside the distributor. Pop the clips or unscrew the hold-downs on your distributor cap and lift it out of the way. You don't usually need to pull the spark plug wires off, just move the cap to the side.
Finding the High Point of the Cam
Inside the distributor, under the rotor (which you can just pull straight up and off), you'll see the points and the distributor cam. The cam is that bumpy, multi-sided shaft in the middle. Each "bump" or lobe on that cam corresponds to a cylinder in your engine.
To know how to set gap on points correctly, you have to get the "rubbing block" of the points—the little plastic part that rides against the cam—to sit exactly on the highest point of one of those lobes.
This is where your ratchet and socket come in. Put the socket on the crank bolt and slowly rotate the engine clockwise. Watch the points as you turn. You'll see them open and close. Keep turning until the rubbing block is resting on the very peak of a cam lobe. When the points are at their widest possible opening, that's when you measure.
The Actual Adjustment
Once you're on the high point, take the feeler gauge that matches your engine's specs (check your manual, but .015 to .020 inches is pretty common). Slide it between the two metal contact faces of the points.
If it's too loose, or if you can't even get the gauge in there, you need to adjust. Look for the adjustment screw—it's usually the one sitting in a slotted hole on the base of the points. Loosen it just a tiny bit. You don't want it floppy; you just want enough movement so you can shift the points.
Most distributors have a little notch where you can stick a screwdriver to pry the points open or closed. Move them until the feeler gauge fits with just a slight amount of drag.
The "Feel" of the Feeler Gauge
This is the part that takes a minute to master. You aren't looking for a tight squeeze, and you aren't looking for a loose gap. A common way to describe it is like pulling a single sheet of paper out from under a heavy book. You should feel the gauge touching both sides, and there should be some resistance, but it shouldn't be so tight that you're forcing the points apart further.
If you're using new points, they're flat and easy to measure. However, if you're adjusting used points, they often develop a "pit and hill" (one side gets a hole, the other gets a tiny mound of metal). A feeler gauge will only measure the high spots, which can give you a false reading. In that case, it's usually better to just replace them or use a dwell meter if you have one.
Why Does This Even Matter? (The Dwell Connection)
You'll often hear old-timers talk about "dwell" in the same breath as point gaps. Dwell is essentially the amount of time (measured in degrees of distributor rotation) that the points stay closed.
When you change the gap, you're changing the dwell. A wider gap means the points stay open longer and closed for a shorter time (less dwell). A narrower gap means they stay closed longer (more dwell). If you get the gap right, the dwell usually follows. But if you really want to be precise, you can check the dwell with a meter while the engine is running and fine-tune it from there.
Just remember: Changing the point gap changes your ignition timing. If you move the gap significantly, you absolutely must check your timing with a light afterward. If you close the gap, you retard the timing. If you open the gap, you advance it.
Common Mistakes to Avoid
One of the biggest mistakes people make when learning how to set gap on points is leaving oil or grease on the contact surfaces. Even a tiny bit of oil from your fingers can cause the points to arc and burn, which means you'll be back inside the distributor in a week wondering why the car won't start. After you've set the gap and tightened the screw, it's a smart move to slide a clean piece of cardstock or a business card through the points to soak up any oils.
Another classic error is not tightening the adjustment screw enough. Engines vibrate—a lot. If that screw isn't snug, the points will eventually shift, the gap will close up, and you'll find yourself stranded on the side of the road.
Finally, don't forget a tiny dab of distributor cam grease on the rubbing block. Just a tiny amount! If you leave it dry, the plastic rubbing block will wear down quickly against the metal cam, and your gap will disappear before you know it.
Finishing Up and Testing
Once you're confident in the gap and everything is tightened down, put the rotor back on and snap the distributor cap back into place. Clear your tools away from the engine bay—you don't want a stray ratchet getting tossed into the radiator fan.
Fire the engine up. If you did it right, it should start quickly and idle smoothly. If it's stumbling or backfiring, go back and double-check that you didn't accidentally bump the distributor housing and change the timing, or that you didn't leave the points too wide.
It might seem like a lot of steps the first time you do it, but once you've figured out how to set gap on points, it becomes second nature. It's one of those basic maintenance tasks that keeps these old machines alive and well. Plus, there's nothing quite like the pride of knowing your car is running great because you took the time to do it the manual way. Now, get out there and get those points gapped!