You need to understand that the crankshaft rotates 720 degrees (or 2 complete turns) for a cycle to take place in a 4-cycle motor. Each piston comes to top dead center twice, once on the overlap period and the other on the combustion period.

Remove all spark plugs to make the motor easier to turn over with a breaker bar and socket on the harmonic damper retaining bolt head. Have a buddy (maybe Glenn will drive over) hold his thumb over the #1 spark plug hole while you turn the crankshaft clockwise with the bar. As the piston comes up on the compression stroke, your buddy will begin to feel pressure on his thumb. While watching the harmonic damper inertia ring closely, continue to turn the crank until you get indicated TDC on the inertia ring/timing tab on the front cover.

You may have to use a long screwdriver to line up the slot in the distributor drive shaft as you look down into the hole where the distributor goes.
As if we were standing on the motor and looking down on it, we will want to point the rotor tab at #1 cylinder, approximately 5:30 o'clock if you look at a clock face. Position the distributor housing so that you can twist it both ways without the vacuum advance can hitting on the intake manifold. Replace spark plugs. Using your longest spark plug wire, plug it into the 5:30 position on the cap, coinciding with the pointer on the rotor at 5:30 and run the other end of the wire to #1 spark plug. The longest wires will be for #1 and #2. The next longest wires will be for #3 and #4. Next longest for #5 and #6. The shortest wires will be for #7 and #8. Going around the cap in a clockwise manner, the next hole in the cap will take the wire for #8 spark plug, then #4, then #3, then #6, then #5, then #7, then #2.
Through the years, the timing tabs and front covers get mixed up on these motors, so you really should find top dead center and use the proper mark on your harmonic damper to line up with the timing tab on your front cover. Now, depending on where the timing tab is on your motor (there were at least 3 different sets of timing lines and tabs used on the SBC), you might have to rotate the distributor housing a little one way or the other to get the motor to fire off, but unless I miss my guess, SHE WILL FIRE OFF. Have a timing light affixed to the #1 spark plug wire, adjust timing to about 32-36 degrees BTDC w/o the vacuum advance hooked up and lock the distributor down.

Determining TDC is the procedure for finding TDC with the motor assembled.
http://www.crankshaftcoalition.com/w...op_dead_center

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