Tom,  The P-Ports will be NC milled.  I don't think it is necessary
 > to thread the insert although this is what Jim Mederer says.  I know
 > that others have not threaded and have not had problems.   The angle
 > of the insert is another question.   I would prefer it to be
 > perpendicular to the housing. However,  this places the runner at a
 > weird angle if you intend to go over the top of engine.  Better to
 > just have a couple of 90 degree bends that can be readily bought.   I
 > am not locked into anything yet.   The P-Port timing is still a
 > mystery to me.  I tried to compare Paul Yaw's numbers with the tech
 > drawing of the Lemans ports and they did not coincide.  Maybe I did it
 > wrong.    I would be  happy to just copy the Power Sport ports, if
 > only I could.  Jerry
 > --
 > Jerry Hey

Quite an effort going on here. My I suggest that the runner should be
parallel with the horizontal. The bottom edge of the port left sharp, with
just a hint of a radius. This to reduce exhaust gas dilution at low speeds.
The top of the port with a larger radius, for improved flow at high speed. I
would go easy on the closing event compared to the Lemans engine. You can
always extend the closing event with a die grinder later.
Even with a poorly done port, the power will be beyond impressive. The first
time we ran a 12A periphery port, the driver reported oil on the rear tires
or a slipping clutch.

He had never experienced wheelspin before. The Lemans ports appear to be much
larger than the factory 12A ports. The steep angled port would be easy, and
would work OK, but that is not what the factory did. Here is the start of a
home built Pport.
The timing copied from a factory housing.
Lynn E. Hanover

 
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