This month's article is designed to help you tune up your car and get the most performance and economy out of it. The procedure is the same for any vehicle equipped with a points/distributor ignition system.
Before you start working a few things need inspection. Check for broken or disconnected vacuum hoses. Check your PCV valve to be sure it rattles when you shake it. It should be replaced if it is stuck or at 10,000 mile intervals.
I can't emphasize enough how important the headlight vacuum motors are. If they are leaking you will have an engine that gets poor fuel mileage because the vacuum advance unit on the distributor does not have enough vacuum. Idle quality will be poor because the engine is running too lean. Your carburetor will get dirty quickly because unfiltered air is sucked in through the headlight motors. Your air conditioner, heater and defroster will all work poorly because the duct positioning motors do not have enough vacuum to operate. If you cannot afford new vacuum motors just plug the hoses until you can and open the headlights by hand!
Check the air filter. If it looks dirty, it needs to be replaced. Check the carburetor for leakage and do not drive with fuel leaks. Check your fuel pump for oil or fuel leaks. Either condition signals time for replacement.
The vacuum advance unit on the distributor can be checked by removing the distributor cap and sucking on the hose (yes - with your mouth!) and watching to be sure it moves. If when you suck on it you don't feel any resistance the diaphragm is broken and the unit must be replaced. If the unit does not operate it is also possible that the points mounting plate is corroded. Sometimes this can be fixed with some penetrating oil.
Points need to be replaced every 10,000 miles or sooner. The condenser should be replaced at this time also. Distributor cap and rotor should last about 20,000 miles but if they are cracked or have pitted or corroded contacts it may have to be sooner.
There are two ways to set points gap. The first is to adjust them to the factory setting using a feeler gauge (.017 for 289 and 302, .021 for 390). The gap must be checked with the points at their most open position that is at the pointiest part of the points cam wheel. The second way to adjust your points is to check them with a dwell meter after you have performed the above procedure. With the engine idling dwell should be 24 - 29 degrees on small block engines and 26 - 31 degrees on 390 engines. Using a dwell meter allows you to get exactly the right amount of energy to the coil for peak performance.
With points gap out of the way the next thing to consider is timing. With the distributor vacuum hose disconnected and idle set at 625 RPM a timing strobe light should be used to set the distributor to about 9 degrees B.T.C. This setting works well for 289 and 302 engines. Cleveland engines with reasonable compression can use up to 12 degrees of timing. The engine should not ping upon acceleration. If it does, retard timing just enough to quiet things down.
Spark plugs do not come pre-gapped from the factory. Be sure to set the gap on each one before installation. On taper seal spark plugs like all Ford engines use, it is best to put some anti-seize compound on the threads. I personally use KW Copper-Kote gasket sealant. This will ensure a perfect seal every time and the plugs will be easy to remove.
