Replacing and Gapping Points
Your points, once set, should be good for trouble-free operation for at least a year, and most likely more. It's nice every couple times a year to adjust em- and it's not hard, the tools aren't expensive. yeah, you'll probably get a handful more horespower with electronic ignition, but for me part of the fun of old cars is dealing with the old technology. Course, it depends if this is your resto ride, or your custom street machine, or all ways in between. However, if you want to save the $$$ and set your own points, here's how to do it:
You'll need a set of point gappers, which are the same as spark plug gappers but a thinner size- Mopar plugs are gapped at .035, while points are .020 for /6 and .017 for all V8s. You can get a gapper at any parts store for maybe five bucks- it's just a set of little pieces of metal of the right size to stick in there. You need the kind that are a thim strip of metal- the disk kind you can use for plugs won't work because you can't fit it down in there.
Replace the points by popping the side clips on the distributor cap and pulling the cap off, being sure not to knock the wires loose. The points are held down by a single screw (large regular screwrdriver) which you don't want to drop down in the distributor. (this is why I keep a magnet in my toolbox.) There's a wire from the coil which attaches to the points with another screw.
Once you get the old points out, be sure you've lubricated the new points by soaking the little felt wick on better points, or just putting a smear of points grease on the little plastic piece that rests on the central shaft. Bettr points usually come with a tube of this grease. By the way, when buying the points you usually get a choice of the 1.99 kind or the eight dollar kind (or some such price). Always get the better ones- cheap points are no bargain, and good ones aren't expenisive compared to the performance they give.. (cheap points have lightweight springs which can behave unpredicably at high rpms)
Attach the wire, and bolt the new points down barely snugly. Now you need to set the point gap. turn the central shaft (by turning the fan by hand, or by bumping the starter motor a second) so the lump on the central shaft is ppushing directly on the points- in other words, when the points are at maximum opening.
You can adjust the point gap by loosening the holddown screw until it's just barely loose. notice there's a slot for sticking a screwdriver into the points frame, so by twisting, you can move the points frame to slightly open or close the gap. Use teh gapper to measure the distance.
Adjust the gap to .020 for /6s or .017 for V8s. This will get it in the right ballpark, enough to make the car run, and in fact, good enough. If you want o adjust it more exactly and get that much better performance, you'll need a dwell meter. This you can get at any discount auto place. This is an electrical meter with two clips- connect one to the wire that goes between the coil and th distributor, the other to the ground. When you crank the starter (it doesn't have to start) you should be able to read the dwell angle on the meter- it should be 40-45 for /6s and in the 27-34 range for V8s (check specs for your particular V8).
What dwell angle means is the angle of rotation of that central shaft in which the poitns are CLOSED. So... if your dwell is too low, make the gap smaller. If too high, make it bigger. You can check it with the meter and fine-adjust it far better than you can with a gapper tool- and this will give you the best performance. If you are on the cheap, though, don't sweat it.
When it's right, tighten that holdown srew snugly, and then check the gap one more time- it's easy to get it out of whack when you tighten it.
Put the rotor and cap back on. (I'm embarrassed to say how many times I forget to replace the rotor, and funny how the car suddenly won't start.)
One more thing: if you change the point gap, you have to check the timing- because changing the gap changes the point in the shaft's rotation in which the plug fires. So get out your timing light, clip the #1 (front on /6) plug wire, smear a white crayon on that thin line on the harmonic balancer, disconnect and plug the vacuum advance hose between the carb and distributo, and fire er up. I believe your /6 '72 Scamp should be timed at Top Dead Center, but my book only goes to '71. E-mail me if you can't find a spec (your auto parts store should be able to look it up if you don't have a book) or if anyone else wants specs for older stuff, let me know. Anyway, you set the timing by loosening the holddown bolt way down at the bottom of the distributor, then by gently rotating the distributor until the timing light shows the mark where it should be on the little scale. Tighten er down, reconnect the advance, and yer good to go.
All this is much easier than it sounds one you've done it a time or two. This plus a fresh set of plugs, and you've got your tuneup.