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#31

11-27-2008, 09:02 AM

benshere

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OOPS---I almost made it through 08 without making a mistake . Still wish I had my Cyclone back----FE with alum heads and intake--couldnt weigh much more that 500-550

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#32

11-27-2008, 11:20 AM

ClydeSDale

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Quote:

Originally Posted by benshere

The secondaries pull up from vacuum created in the primary venturi's, thats between the "neck down" at the air horns and the butterflies. It works just like one of those vacuum "pumps" in the air conditioning catalogs that use an air compressor blowing over a small port thereby creating a vacuum in that port. The faster the air (venturi) moves over the hole, the more vacuum it creats. Thats why with even "0" manifold vacuum you have vacuum at the secondary opening diaphram.

THE LIGHT JUST TURNED ON!!

It's the velocity of the air the engine sucks in through the venturi that creates the vacuum that opens the secondaries!!

You'll pardon my AH HAH! moment. Sometimes the most simple ideas can be the hardest to grasp. I now think I totally understand it .... or at least got a darn good grip on the concept. I now also see why vacuum secondaries can be so much better than mechanical ones in most street applications. I get "the springs" now too.