I don't quite understand what you are asking, but I think I can clarify one point.
No pair of cylinders fire at the same time, the spark plugs do but one of them is firing on the exhaust stroke (wasted spark).
Just turn the cams so the lobes are pointing away from the valves that you want to check.
Hopefully I don't confuse things more:
The firing order in the following description may not be right, but the general idea is.
Number one cylinder fires, then 180 degrees of crankshaft rotation later (1/2 turn of the crank) number two fires, then 180 degrees of crankshaft rotation later number four fires, then 180 degrees of crankshaft rotation later number three fires.
#1 and #4 pistons reach TDC (Top Dead Center) at the same time, but one is at the top of the compression stroke while the other is at the top of the exhaust stroke. The same thing applies to #2 and #3.
When #1 amd #4 are at TDC #2 and #3 are at BDC (Bottom Dead Center).
I really hope this helps clarify things instead of being confusing
Post edited by: steell, at: 2006/06/19 11:38