Heron Pistons and Larger Valves

[DeWitt Harrison]

On Mon, 18 Dec 2000 16:17:35 -0700, "Bruce Bell" <bbell04 at attglobal.net> wrote:

 > [ ... ]
 > If you are going through this much trouble use the pistons from
 > an 85 or 86 GTI/GLI and  bore the block to 81.5 mm. This should
 > yield you a 10:1 CR. which you can lower by unshrouding the
 > valves while cleaning up the combustion chamber.

I'm curious about what is meant by "unshrouding" the valves in
the context of head work. I've come across this term before
where there can be a shrouding effect due to the close proximity of
the valve to the cylinder wall which then acts as an impediment
to flow. But this seems different. Please fill me in. Thanks,

DeWitt Harrison
Boulder, CO
88 5kcstq