mpgmike said

If I were handed a strange head from an engine I never worked on before, the first thing I would do is look at the story the head wants to tell. Excessive carbon build-up and clean spots are indicators of dead zones. Since velocity is your friend in both the ports and combustion chambers, dead zones are your enemy. How can I eliminate dead zones??

Dimples can excite an otherwise dead zone.
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As for the Somender Singh Grooves, they serve a couple of functions:
- On the Compression Stroke, they give one last "squirt" of guided velocity to homogenize air and fuel.
- On the Power Stroke, then "blow out" the ring lands; this blows the liquid fuel out of the ring land area that was scraped from the cylinder walls on the compression stroke.

In some of the pictures posted, there is only 1 Groove, while in others there are more. I've used as many as 6 on a Ford twin-plug 2.3 Ranger. According to Somender Singh himself, the grooves should be pointed towards the spark plug to bring otherwise unburnable charge to the point of ionizing activity -- the spark kernel. As far as the other end, look for dead zones.
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The Grooves on the Jeep 4.0 head were made using a hand grinder first, then a cone shaped sanding burrel to round off the sharp edges. When I had my speed shop (Powre Haus) I used my mill to gradually carve the Grooves over several passes.

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