Quote:
Originally Posted by DBSHELTON
OK, since it will be raining for the next few days, I decided to go ahead and install my new Snyder 6:1 head. After I got everything apart and all cleaned up, I wanted to find actual TDC since it is real easy with the head off. Sure enough, after getting it all setup and checked, the timing mark was 3 1/2 degrees retarded. Kinda surprised that the Timing Dimple on the new laminated cam gear is that far off. Now I feel much better knowing that everything "Jives"! So there is another 3 1/2 degrees of advance I was leaving on the table for the B Distributor.
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If the head is off like during assembly, I never use the timing pin. It is much easier to use the valves on #4 cylinder to get TDC on #1. Let me explain:
#4 is at TDC after the exhaust stroke at the same time #1 is TDC on compression. At the top of the exhaust stroke, the intake valve begins to open 7 1/2 degrees BTDC and the exhaust closes 4 1/2 degrees ATDC. That means that at TDC, both valves are open, the inlet a little more than the exhaust. If you set the motor with both valves open (equally), you will be 1 1/2 degrees BTDC. At this point, the valves are "rocking". That is, if you turn the motor a little forward, the inlet valve will open more and the exhaust will close more. Go back the other way and the reverse happens.
If you stop the motor with the inlet valve a little more open than the exhaust ON #4 CYLINDER, #1 is very close to TDC and your are ready to set the cam on the distributor shaft. Even with a wildest guess at which valve is more open, you will be within a degree or so of TDC - plenty near enough when you consider that while driving, we change the timing by up to 40 degrees according to ear.
These timing angles are crankshaft degrees.
I always instal a timing scale on the front of the engine and put a mark on the front pulley at this stage and never use the timing pin even if I do have to check the timing (VERY rare).