Points gap is 0.016 inch (32 degrees dwell on a meter); timing on the AMC 258 is 8 degrees BTDC at 700 RPM with the vacuum advance disconnected and plugged. A dwell meter is more accurate than a feeler gauge — buy one before doing this job twice.
Points ignition is what almost every CJ-5 came with from the factory before the HEI/electronic conversion options of the late 70s. The system is mechanical: a set of contact points opens and closes as the distributor shaft spins, breaking the primary circuit of the coil and inducing the high-voltage secondary that fires the plug. Points wear, the gap drifts, and timing wanders with it. A points tune-up is a 60-to-90-minute job that should happen every 12,000 miles or once a year — whichever comes first.
The spec for points gap on the AMC 258 Prestolite distributor is 0.016 inches. That's not a feeler-gauge spec you eyeball — it's a dwell-meter spec, because the angle the points stay closed (dwell) is what actually determines when the coil saturates. 0.016" of gap corresponds to roughly 32 degrees of dwell on a six-cylinder. If you don't have a dwell meter, a feeler gauge gets you in the ballpark — start there, then drive to a parts store with a meter and confirm.
Timing on a 1972–77 AMC 258 in a CJ-5 is 8 degrees BTDC (before top dead center) for 49-state trucks and 6 degrees BTDC for California-emissions trucks. Set it at idle — about 700 RPM with the choke fully open and the engine fully warm. The vacuum advance hose has to come off the distributor and get plugged with a vacuum cap or a golf tee, or you'll be chasing your tail.
The Buick 225 Dauntless V6 (1965–71) used a Prestolite IBS-4001 distributor with similar 0.016" point gap. Timing on the 225 is 5 degrees BTDC at idle. Same general procedure, different spec.
Many owners eventually swap to GM HEI or a Pertronix Ignitor electronic conversion. HEI gives a hotter spark, eliminates the points entirely, and survives the kind of dust and water you find on a trail. If you find yourself doing this job twice a year, the conversion pays for itself in time and reliability.
| Part | Vendor | Est. price |
|---|---|---|
| Standard Motor Products points set (Prestolite distributor, AMC) | Standard | ~$18 |
| Standard ignition condenser | Standard | ~$9 |
| Distributor cap (AMC 258 Prestolite) | Standard | ~$22 |
| Rotor (AMC 258 Prestolite) | Standard | ~$8 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.