ollie said:
The easiest way to disconnect the spark is to loosen and slide the dizzy cap away from the dizzy base.
[...]
crank the motor for a few seconds(say like 3 to 4 seconds)
Since nobody else seemed to mention it, you want to do the test with the engine fully warmed up. You probably won't get the same numbers on a cold engine as a warm one... Metal expands when heated, which affects the clearance between various parts - the piston and cylinder wall included.
The easiest way to disable the ignition that I've found is to unplug the distributor's 2 pin electrical connector. The heavy blk/yel wire is the distributor's power feed coming from the ignition switch. Without it, the ignition coil can't be energized so no spark can be generated. Sliding back the distributor cap simply prevents the high voltage pulse from being transfered to the spark plug wires... Who knows where it's going instead.
To cut off the fuel, remove the "ECU" fuse from the underhood fuse box. Without it, the fuel pump won't prime and the injectors won't fire. In truth, the ignition shouldn't work either, but I prefer to unplug the distributor connector just to be safe.
As for cranking time, I've always positioned the compression gauge in such a way that I can see the needle from the drivers seat. Then simply crank the engine until the needle stops twitching... It's typicly 8-10 seconds. With all the spark plugs out, there's a good bit less load on the starter motor, so cranking the engine doesn't run the battery down nearly as much.
