Editing Valve adjustment SBC/BBC (section)
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==Setting ignition timing== Leave the distributor clamp a little loose so we can rotate the distributor housing. 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 if the distributor was removed. 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 valve covers. Replace spark plugs. Using your longest spark plug wire, plug it into the 5:30 position on the cap, coinciding with the tab 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 [http://www.crankshaftcoalition.com/wiki/Timing_tabs_and_damper_TDC_lines_SBC sets of timing lines and tabs] used on the SBC before the plastic timing covers were used), 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 (for now, it will be reattached to a vacuum source after the cam has been broken in if needed) and lock the distributor down. [http://www.crankshaftcoalition.com/wiki/Determining_top_dead_center Determining TDC] is the procedure for finding TDC with the motor assembled. If you can follow these instructions, the valves will be adjusted properly and the ignition timed and ready to start. Be sure if the engine is newly assembled or has sat for an extended period of time that the oil system is first primed before starting the engine. ======Alternative view/terminology====== <font size="1">NOTE: As with any single "center camshaft" engine (that is fitted with Hydraulic Cam Followers [aka lifters]), we are NOT actually adjusting valves. The term "adjusting valves" is a carry-over from the old days when mechanical valve operation was common. For these, there was an actual valve stem-to-follower clearance adjustment that was required. With Hydraulic Cam Followers (originally coined "self adjusting"), we are adjusting the rocker arm stud nut height as to change the push rod geometry as to positon the cam follower plunger "depth" within the cam follower body. Many hydraulic plungers will have a hydraulic functioning range of around .100" or so. The goal is to set the plunger at it's OEM prescribed depth within the follower body. Here is an image that shows a cam follower as it becomes hydraulically active. Note the plunger and it's travel within the follower body. http://www.youtube.com/watch?v=lorANZ1Tptw This adjustment can be done statically or dynamically. When this initial adjustment is done statically, I highly recommend that we stop the crankshaft in as many "stops" as there are cylinders. IOW, for a V-8 engine, we use the 8 stop procedure, beginning with #1 cylinder @ TDC C/S (right down the engine's firing order)..... not the 2 or 3 stop procedure that is sometimes recommended. </font>
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