Re: Compression - is it important ?

Posted by PackardV8 On 2011/2/21 7:49:11

With spark plugs that are just loose the engine was probably not loosing much compression. SOME but not much to notice. Just the sound was noticed.

8 cylinders are very forgiving of lost efficiency because they are usualy bigger and more powerful than what average John Q Public has ever needed anyway. Try it with a 6 cylinder or 4 cylinder. e.g. loose one cylinder of a 4 cylinder engine and loose 25% power.

I am surprised that just loosening the spark plugs a couple of turns allowed for enuf compression release to allow easy turning of the engine by hand. Based on my experience the spark plugs have to be removed completely before any relief is allowed for any ez turning of the engine by hand.