Fuel Efficient 360

["Bruce Hevner" <scramblr@xxxxxxxxxxx>]

>the ports on the 304 are the same size as the 360/401. The only change is
in the valve pocket/seat >area. I'm not sure this would boost velocity a
whole lot, but it should boost it some.

That's right, the port OPENINGS are the same but the "pocket" area IS
smaller. And that's the important part. By using a smaller pocket/valve the
velocity is increased making the flow speed up at that point. Faster flow is
also more responsive. 
 If you remember back when Ford was doing a lot of work with their "Wedge
427" motors one of the things they did was put a "venturi" directly under
the valve seat to speed up intake flow past the valve. New heads came with a
warning NOT to remove this venturi. To do so would cause up to a 20HP loss!
These things had fully machined chambers.
 So,,, what you should shoot for is a large bowl area under the valve
leading to a "venturi" and then to a radius valve seat blending smoothly
into the combustion chamber.
 This is a GENERAL statement covering "bathtub" type chambers. There are
some "flat style" combustion chamber heads where having the valve "stand
tall" works better. This is where the seat is on the inside of the valve
causing the valve to protrude above the seat.
Ain't flow benches fun???
For a better understanding of combustion chambers and their affect on power
read some of Sir Harry Ricardo's books, the guy was a real genius!!
www.oldengine.org/members/diesel/Misc/Ricardo.htm
Bruce Hevner
  

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