Question
If the heads are on and the spark plugs are in, then when you turn the crank, the cylinder is still going to draw in air...then compress it...that is why the crank is a little difficult to turn...once you get past the compression stroke and into the power stroke of the engine that compressed air starts bleeding off as the exhaust valve begins to open. This is normal. If you want it to stop OR if you want to make the crank easier to turn, take the spark plugs out. The air will be pushed out through the spark plug socket instead of compressing, so the crank will turn MUCH easier and it will alleviate some of that sound.
