See full version: How to Set Points on a Small Block Chevy
Place the negative battery cable back onto the terminal. Instruct your assistant to "bump" the ignition key back and forth, turning the engine over in short bursts, until you see the high point on the distributor shaft---eight or six-sided cam---stop and rest directly under the small rubbing block on the points. This will be the correct adjustment position. more
Disconnect the negative battery terminal. Use the proper width blade on the feeler gauge---refer to manufacturer's specifications---and place the blade between the two point contacts. Use a slot screwdriver to wedge the points open or closed by sticking the screwdriver blade into the small slot in the distributor base. Adjust the points closed over the feeler gauge until a slight drag can be felt when inserting it and pulling it out. Fully tighten the points' mounting screw after achieving the adjustment. Use the distributor adjusting tool or the proper size Allen wrench to make the adjustment on the newer model Chevy distributor. Most gap points for Chevy small-block engines require .016 to .019 of an inch.
Reinstall the new or used rotor by pushing it down over the distributor shaft or secure it with the screws if equipped with them. Place the distributor cap back on in the same position you removed it and turn the mounting screws in the cap 90 degrees to secure into place. Reconnect the negative battery cable. more
Use a slot screwdriver to turn the two distributor cap mounting screws 90 degrees out until they release. Pull the distributor cap off and set it aside in the engine compartment without removing the wires. Pull the distributor rotor straight up and off. In the case of a round rotor cap that has two screws, remove the screws with the slot screwdriver and lift off the rotor. Don't lose the rotor mounting screws. [links]
Place the new condenser and points on the distributor base, aligning their positions with their small mounting guides. The points will have a small pin that fits into a pivot hole in the distributor. Place the mounting screws on the points and condenser and tighten them down very lightly with the slot screwdriver. Tighten the condenser down fully; leave the points adjustment screw slightly loose. Push the points wire and the condenser wire back into their small, spring-loaded mount or tighten them with the screw, if so equipped. [links]
There's a lobed cam on the distributor shaft that pushes on a small rubbing block on the movable side of the points. As the cam and distributor rotate, the points open and close constantly. As they close, current from the ignition switch flows through the contacts into the coil's primary windings and then off to ground. This current generates a magnetic field in the coil's iron core. When the points open a few degrees of crankshaft rotation later, the current is interrupted, causing the magnetic field to collapse. This induces electrical current into the secondary windings of the coil, where the current is raised to 20,000 volts or more. The high voltage now travels over to the distributor, where the rotor metes the high-voltage pulses out to the correct spark plug.
Modern engines use computer-controlled factory-preset self-adjusting ignition systems that never change their timing, have no moving parts and never need maintenance. Yay! A generation ago, every teenager, every mechanic and a lot of vehicle owners understood the theory and practice of changing points and setting the timing. Nonetheless, there are still plenty of older vehicles, outdoor power equipment, boats and tractors that need periodic adjustment or replacement.
The distributor on these older vehicles performs two related tasks. The first uses a simple on/off switch, the ignition points, to provide properly timed pulses of 12-volt electricity to the ignition coil. In the coil, essentially a transformer, it's stepped up to 10,000 to 20,000 volts. Then, the high-voltage electricity from the coil returns to the distributor, where the rotor inside parcels it out to the correct spark plug to ignite the fuel/air mix.
All that current flowing across the points doesn't like to stop suddenly, and can initiate a small arc, which eventually erodes the tungsten contacts. The condenser cushions that arc, making point life much longer. But not infinitely long. As the contacts and the plastic rubbing block, which contacts the point cam, wear, the ignition points' clearance and timing constantly change. After thousands of miles, the timing has shifted enough to affect performance, and the ritual of changing the points and setting the timing becomes necessary. How often? Some vehicles need to have the timing adjusted as often as every 10,000 miles to maintain peak performance. High-revving engines will need premium points with a high-pressure spring to keep the points from bouncing at increased revs. Some points assemblies include the condenser, yet for others, it's a separate part. Condensers are inexpensive enough that it makes no sense not to replace them with every set of points. They should last as long as a set of points, 20,000 miles at least. [links]
You are correct that dwell should be 28°-32°
Loc: Gilbert, AZ
Reg: 01-16-07
so, flash forward to the next day, with the ignition coil replaced(i replaced because i wasnt getting a spark to the plugs) my six-shooter fired up once more. it lived. then the next day, after pulling into a micky d's for a bite to eat, my truck decided to be a stubborn SOB and wouldnt start for just over an hour. while cranking, i could hear the engine TRYING to fire, but it just would not live. finally, i did managed to get it started, and i made a beeline for my house.
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