spica manifolds

[Norm Riffle <normriff@xxxxxxxxxxxx>]

	Back in the mid 80's i was doing some autocrossing with some modest
success. Not particularly inhibited by rules my engine has 11:1 comp, 11
mm cams, head porting, O/S valves, drilled  # 2-4 mains etc. etc. etc.....
	....and the spica manifold and pump. ( i was not aware that
KNOWLEDGEABLE Alfisti held the spica unit in contempt) later, i upgraded
to the Ingram modified pump.
	It didn't make sense to me either, that i should do all the work to the
head, valves etc, without some treament to the intake manifold.
	I swear it took me 10 hours to port that thing out.....
	I noticed a slight amount of difference at the upper end of the rev
band. (maybe) And a corresponding loss at the low end. The next time
that motor gets major service, I''m gonna take that manifold off, and
put a stock one back on.
	For autocrossing, i've found the most useful power available is midrange.
	So, like everything "performance wise" it depends on what you're after. 
	Even if the spica manifold does get as small as a weber manifold, it
still doesn't have to suck fuel out a venturi.
	There is however, something to be gained by modifying the intake
manifold. Jon Norman, may still offer 45mm throttle bodies for the spica
system, probably does more to improve the flow and would probably
reccomend porting to the manifold on this conversion. So, if you
regularly need 7500 RpM out of heavily modified street motor, this would
be a way to go.
	For me, the time would have been better spent reading a book on how to
drive faster. ( or changing the intake cam timing, checking tire
pressure, valve clerances....the mundane stuff.)

Norm
Oregon City,OR

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