Vacuum Advance for A-Engine For many years the standard production A-engine distributor has been equipped with the vacuum-advance electronic hardware and also served as the basis for the standard performance distributor. Stock distributor springs are usually too stiff for a performance application. These springs are easy to replace by hand or with needle nose pliers. Turning the screws counter-clockwise richens the mixture, If there is a vacuum leak, it must be repaired before the idle mixture can be properly adjusted. Gap Magnum plugs use a gap of. It was originally a five-wire harness, but that was updated to a four-wire harness. Electronic Ignition Have you added Electronic Ignition to your truck or purchased one fortunate to have it already? If you want distributor adjustment in your Magnum engine, the solid-shaft distributor must be replaced.
I favor Chrysler ignition boxes. Production used two springs: one light and one heavy with a loop in the end. On the stock distributor, you have to weld and file it to the right length. You pry from both sides evenly and its easy. The curve should steadily increase only a few degrees at every 500 rpm, until it reaches the maximum 3,000 — 3,200 rpm.
If you are unsure about any of the above, consult the Mopar Performance Engine Modifications Manual. Changing the springs will give you an advance curve that starts at about 1,000 rpm, and ends at around 3,000 — 3,200 rpm. The vacuum advance increases timing as the vacuum created by the engine increases idle and low-load conditions. The ballast resistor may begin to smoke after the initial startup. It is designed for street engines that operate at less than 6,000 rpm.
The mechanical tach version has a small tab that protrudes from the lower lip of the cap, and the bracket that holds the cap on has points that the tab centers in. The tach should have a low-scale readout that is sensitive to increments of at least 50 rpm. At this point we need to get the distributor spring clamps out of the way so the degree wheel will sit flat. Its shape defines the advance rate and the maximum allowable advance, and modifying the shape of the center plate is easy and yields significant results. The springs in a Mopar distributor are under the breaker plate.
Then, i pull the advance mechanism out by removing the two screws then separating the pickup plate a bit until it comes out. I just snapped in two large sockets on each side so the wheel has a flat stable surface to rest on. To discuss the ignition system for street and performance applications you have to know what spark advance is. A dyno won't tell you how stable your idle is in gear at a stoplight either. Vacuum advance is tricky to tune because there is no direct measurement available like when dealing with total.
It works fine if you switch from a points ignition to an electronic coils are not generally included in electronic ignition kits. A sensor the black disc and wire is inside the housing and it helps the computer with timing. Stock canisters typically provide 22-24 degrees of advance. Aftermarket spring kits come with springs of varying tension, and you can mix and match the springs until you get the advance rpm you need. I use two large screwdrivers and pry straight up without disturbing the pickup. This bracket is designed with timing adjustment capability.
For street applications and higher-energy ignitions systems, I recommend 7. Wiring Most aftermarket ignition kits come with their own wiring, as did the electronic ignition kit. This bushing is the last place you want oil and it takes a beating in high-mileage applications. The unit is held in by two screws so remove the screws and remove the arm from the vacuum advance plate. Set the basic timing for total mechanical spark advance. Stock or mildly tweaked engines generally idle at 16-18 inches of intake manifold vacuum between 750 and 900 rpm. The housing is made of aluminum so it is very lightweight.
The two-wheel-drive unit is different from the four-wheel-drive unit, the 5. The gap in the heat shield should be pointing upward. Always drive within your ability and experience level and consistent with conditions. For example, assume that your distributor has 22 degrees of centrifugal advance built into the advance mechanism. If you have a new block, make sure that you have a distributor drive bushing pressed into the block. In this piece we deal with igniting the spark that lights the fire.