Points are electrical contact points that work off a cam on the distributor shaft that can be seen with the cap removed. As the distributor rotates, the contact points are adjusted to ride the shaft where raised lobes push the contact points open and closed as the dist turns. If you remove the distributor and turn it by hand you'll see how this works. The the rotor and distributor cap then take the current and send it to each spark plug in a particular firing sequence called the firing order. The distributor must be installed and adjusted correctly for the ignition timing to be in sync with each rotation of the engine. Contact points have an adjustment that allows them to open and close to a certain gap tolerance measured using a gap measuring device. A manual describes this and also gives you exact numbers as to point gap, timing (measured using a strobascopic timing light pointed at a mark on the the crankshaft pulley or harmonic balancer.) If the distrutor has been removed, you line up reinstallation by placing the number one cylinder at top dead center on the compression stroke. The metal "pointer" on the rotor should then be aimed at the number one plug wire on the cap. Distributor is then dropped in and turned to fine tune the timing. You need a manual and/or someone to take you thru the process. Once you see it, you'll find it's incredibly simple. You need current from the battery to the bat side of the coil and then a small wire from the dist side of the coil to the dist. You can bypass an igition switch by using a jumper wire from the battery to the bat side of the coil and then crank the engine using a starter button either the one in the truck or one you make up and attach to the starter for this purpose.
NB: Some of these old trucks have a balast resistor that lowers the voltage from the battery to the distributor (to 9 volts?). I don't know too much about that as I have eliminated this on my truck but I'm guessing that if you have one, it's a white ceramic device located on the firewall and you would need to come off that with your jumper wire to the + side of the distributor if you are bypassing the ignition switch. Otherwise you might burn the points. Am I right about that guys?
