Originally Posted by frog
Here's how I understand it...
In the picture above, the decomp. plate only replaces the same amount of material that was removed by the skim(s).
However, because the walls of the plate are vertical, the squish area has changed shape.
Over to you Stu...
Not quite, i think you are getting confused about what the where the squish area is: (this is how i've understood it so far)
The red blobs on the leftmost diagram show the squish area, as the piston travels up the bore, the mixture is guided towards the centre of the combustion area. Now if you skim the head alot (middle diagram) or remove the squish area, there is alot less (sometimes nothing) squish area to guide the mixture to the centre of the combustion area. Adding a decompressin plate does nothing to aid this, as it is just an extension of the bore, it makes more space between the top of the piston and the cylinder head, but doesn't put back your squish area
