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Finding 1 CYL TDC

7547 Views 3 Replies 3 Participants Last post by  JoshCampbell
OK, this shouldn't be that difficult but I've been going through the manual and the forum and am having a hard time finding out to make sure my #1 Cyl is at TDC. I'm in the middle of replacing the distributor and need to make sure I'm at least close enough on time to time it.....I feel a little foolish asking but have spend about an hour and a half looking....
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Turn the crankshaft clockwise until the mark on the pulley lines up with the 0 notch timing mark, then make sure the rotor is pointing to the #1 cylinder. Simplest way I know. Good luck.
OK, tell me if I'm wrong on this.....I know what the position of the rotor in the old distributor was. I put the new one on with the rotor in that position.... am I close? I still have a lot of putting things on to go before I'm ready to fire the engine, but as I was thinking things through it seemed that this would work.
Don't feel foolish- I spent over a month researching this and still found no solid answers. Ridiculous. In the end I went to the extremes, but was rewarded with confidence.

1. Removed #1 spark plug
2. Removed distributor cap
3. Removed valve cover (new seal is cheap anyway)
4. Connected gauge to #1 spark plug well
5. Rotated Crank Pulley until pressure began rising on the compression gauge (compression stroke).
A. Observed Crank Pulley land on TDC mark (first notch on the left)
B. Observed Distributor land on #1
C. Observed #1 valve rockers both up while reaching TDC mark (indicating valves were closed)
D. Observed L and R Cams were at their 11:00(R) and 1:00(L) positions
6. Disconnected compression gauge
7. Placed a pen magnet in the spark plug well and rotated the Crank Pulley back and fourth (using hands) until I observed the point where the magnet began to move down, then backed the Crank counterclockwise a smidge.
8. Double checked everything (Cams, Crank Mark, valve rockers, distributor, etc.). At this point you're guaranteed to be at TDC.

NOTE: As mentioned above, I took it to the extremes, because I don't like ambiguity. You can get away with just using a Compression gauge and observing the timing marks for finding TDC, it's just depends on how accurate you want your timing to be. One thing I did conclude throughout my extensive research is that setting timing is not a black & white procedure- It's actually a science of fine tuning. For example, after getting my timing set back to factory specifications (using timing marks) I realized the #1 plug fires at the point in which the #1 piston initially reaches its apex. In other words, it fires as the piston is coming up and not when it starts going down. Looking at this from a physics perspective, the piston still has a good amount of kinetic energy when the spark plug fires. Not only does the force of the spark cancel out the existing energy in the piston it's also working against it to send it in the opposite direction. I'm sure it's not optimal for the piston and rings either. You want the plug to fire just before the piston starts to drop. Like pushing someone on a swing. You don't push while they're still coming at you, you push when they start falling back down. Again, Just an observation I made while studying the Engineering side of things.
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