Manifold and head grinding

[Andrew]

I'm sure grinding ledges like this out of my intake manifold and heads is a good idea, but does anyone have any idea how much difference it actually makes?

 

[Cranky]

Do a pocket job too....in the heads. The area just under the valve is where the factory backcut sucks. If you don't do any other porting, at least to that. You clean up all the garbage and blend the pocket into the port and you can tear drop the protrusion of the guide too but smoothing all the edges helps. Make sure the air flow hits no steps. Air flowing down a step goes much better than air trying to flow up a step. Another thing to do that most don't bother with is to blend or relieve the head to the cylinder. You can do this by first spraying dykem spray to the head deck and 2 bolting the head your empty block then scribe a line around the edge of the head then grind the chambers to the line. This 'unshrouds' the head to the block. It doesn't have be be a square grind but just round off the edges that hang over into the cylinder.