Removing Distributor Without Affecting Timing

If you have a good spark at the coil lead (king lead), you have a functional low tension ignition circuit and a functional coil portion of the high tension ignition circuit. Thus, car detail no reason to remove the distributor from the vehicle. The rotor, distributor cap, the coil lead and the spark plug leads–the high tension circuit components, can all be changed without removing the distributor from the engine.
If you have a good spark at the coil lead, install the lead fully into the center terminal of the distributor cap, then check for spark at each of the spark plug leads after ensuring that all of them are fully seated into the distributor cap. If none of the leads shows a spark, the problem is with either the rotor or the center carbon bush of the distributor cap.

As to where the rotor terminal is going to point, it depends on which portion of its cycle the engine is in. Remember, the engine is a four cycle (for stroke) engine and the distributor operates at one half the engine speed because of this. Thus:

Number one cylinder is on the intake stroke, drawing in fuel as the rotor is moving to fire the number two cylinder. Near the bottom of the stroke of number one piston, number two piston is a few degrees before its top dead center and the rotor moves into alignment with the terminal for the number two spark plug wire, firing the spark plug on that cylinder.

Number one cylinder begins it’s compression stroke, moving upwards, as the rotor moves, counter-clockwise, towards the number one cylinder’s terminal of the spark distributor cap. As the number one piston reaches a few degrees before top dead center, it is fired.

After number one cylinder is fired, number three fires as number one begins its exhaust stroke. As number one completes its exhaust stroke and begins the intake stroke, cylinder number four fires. Thus, both cylinders four (firing stroke) and cylinder one (end of the exhaust stroke/beginning of the intake stroke) will have both the intake and exhaust valves closed and the rotor’s end terminal will be pointed at the distributor cap terminal for cylinder number four.

The best way for an inexperienced mechanic to determine if the distributor is properly aligned is to remove the rocker arm cover, then rotate the crankshaft using a 1 5/16″ wrench or socket while watching the intake valve (second from the front of the engine) open, then close. As the valve is closing, rotate the engine, clockwise when viewed from the front, to the timing marks. At about 10 degrees before top dead center, the rotor should be pointing to the number one cylinder’s terminal on the distributor cap–which ever terminal that may be.

Attach the number one cylinder’s spark plug lead to that terminal, then attach the other leads to the terminals, going counter clockwise in the order three, four, two.

Yes, it is possible to make a mark on the distributor body and engine, remove the distributor, reinsert the distributor and have the timing very close–sufficiently so that the engine should start. A better way is to hook up a dynamic timing light to the number one spark plug lead, have an assistant crank the engine over, and rotate the distributor until the light is flashing on the timing marks–it will fire if the light is flashing when the line on the harmonic balancer is in line with the timing marks on the engine. Good trick to know sometimes.

But, not right now. You state that your low tension circuit is working correctly. It would be rather foolish to add yet another variable into the system by removing and replacing a working system. Wise to remove the valve cover (which does not affect engine operation) and verify the orientation of the distributor by watching the intake valve move. But, only as a peace of mind issue. If you did not remove the spark plug leads from the distributor cap (there is no need to) when you removed the cap, there can be no change. It only fits on one way.

If you removed the spark plug leads from the spark plugs, verify that the spark plug leads are installed on the distributor cap in the correct order.