It is remarkable how far ignition systems have come in more than a century of use with internal combustion engines. For a long time it was that open/close breaker points thing, which wasn’t always reliable, sometimes leaving you on the roadside or bouncing like a maniac at high rpm causing crummy performance and misfires. Ignition points rubbing blocks wear over time and with mileage and have to be replaced. In the 1970s, Detroit automakers introduced solid-state ignition for the masses. The result was the need for fewer tune-ups and less concern over the need for a tow truck.
When PerTronix introduced the simple drop-in Ignitor module decades ago it was heaven-sent because you could convert an old Delco distributor to electronic ignition in a matter of minutes. Seriously—remove the old ignition points and condenser and install the Ignitor. It’s that simple.
We’re working with a tach-drive Delco distributor from a big-block Chevy in need of fresh parts and custom tuning by Ted’s Carburetor Shop in Lancaster, California. Back in the day this guy was fitted with window-adjustable ignition points. Today, we’re installing the original PerTronix Ignitor module, which eliminates points and the 12,000-mile tune-up. The PerTronix Ignitor, Ignitor II, and Ignitor III all take 15-30 minutes to install. Rebuilding the classic Delco distributor takes an afternoon.
1. The tach-drive Delco distributor, used from 1962-’74 on small- and big-block Chevys, scattered across an assembly table at Ted’s Carburetor Shop. Rebuilding one of these Delco distributors involves close inspection of each part along with making critical decisions about each part. Excessively worn parts must be either replaced or serviced.
2. There are two types of distributor rotors. On the left is the old Bakelite rotor, long used in these distributors. On the right is a more contemporary plastic type. It’s always a good idea to check continuity between the center and outboard terminals, which has been known to be marginal in some replacement rotors. Continuity must be consistent. Wiggle the center terminal and watch the resistance (ohms). If there’s any fluctuation, do not use the rotor. Which reminds us, did you check the distributor cap for carbon tracking and cracks?
3. Assembly begins with a generous coating of molybdenum grease at the new bronze bushings.
4. Next, the nylon thrust washer is installed.
5. A new vacuum advance unit is installed and secured. Now is a good time to insert the Ignitor wires down through the housing and pull the grommet into place.
6. The breaker plate is positioned and secured, then checked for freedom of movement.
7. The PerTronix Ignitor is positioned with the wires routed where they won’t chafe on the breaker plate.
8. The shaft and centrifugal (mechanical) advance mechanism are assembled along with the limiters.
9. The distributor shaft is generously lubricated with molybdenum grease before installation in the distributor housing. The tach drive (arrow) gets a heavy dose of grease. You may also use engine assembly lube for these Delco builds.
10. The PerTronix reluctor ring is installed next and secured to the mechanical advance. Threaded studs reach through the rotor and are retained by locknuts.
11. Centrifugal advance flyweights and springs are next to be installed. The limiters and springs chosen depend upon the application and what is learned on the distributor machine. The combination of flyweight springs and vacuum advance programming determine spark curve. The spark curve is dialed in based on engine dynamics (cam, intake, heads, carburetion, compression ratio, and the type of driving expected most of the time). PerTronix offers a performance advance curve kit for Delco distributors.
12. These are mechanical advance springs and limiters. When it’s time to dial in the spark curve, tuning is determined by spring tension and how far the rotor is allowed to advance. Limiters determine how much the rotor can advance. Spring tension determines the rate of mechanical advance based on rpm.
13. We have installed flyweights, springs, and limiters for baseline testing. The springs and limiters are swapped as necessary during distributor curving.
14. The shaft is installed next and seated before the drive gear installation and endplay check. This particular Delco distributor has the original Ignitor, which has worked like a champ for many years. There is the option of stepping up to the Ignitor II or Ignitor III. The Ignitor III is a programmable module with a built-in rev limiter.
15. The distributor gear is installed and endplay checked. Because we’re running a hydraulic roller cam in the 427ci big-block, where this is headed this is a steel gear designed to work with the steel camshaft. A cast-iron distributor suggested endplay is 0.005-0.008 inch. If you’re building an aluminum Delco, endplay is 0.012-0.015-inch. Aluminum housings run larger because aluminum expands more aggressively.
16. We’ve laid the tach-drive components out for your convenience.
17. The tach-drive is installed as shown.
18. Ted Granger of Ted’s Carburetor Shop dials in the spark curve. This is a task best left to a professional if you want seamless performance. However, this is also something you can do in your driveway with a timing light and behind the wheel. The best advice we can offer is to take your vehicle to a reputable tune shop with a chassis dyno where the ignition timing and fuel curves can be checked with the vehicle on rollers under a load. The biggest mistake here is too much timing and a lean fuel mixture, which can net you engine damage.
19. PerTronix offers three levels of Ignitor retrofits for classic Delco distributors. The original PerTronix Ignitor has been around for decades in wide use around the world in virtually every application imaginable.
20. The Ignitor II is a “smart” module, which can sense current levels and adjust dwell as you drive.
21. The Ignitor III delivers three times the spark than your Delco’s original contact points. What’s more, it has a built-in rev limiter you can adjust to your own comfort zone.
Photos: Jim Smart