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Old 07-25-2013, 02:42 AM
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Quote:
Originally Posted by zrayr View Post
In the context of high performance engines that forum members are likely to be using in a Cobra or other lightweight high performance classic, people I know that had to have vacuum reservoirs and such, ONLY had to do so due to a radical cam that had too much overlap to allow for much manifold vacuum. That was only a concern when vacuum was needed for power brakes, steering, etc.

People that had the sense to do without power brakes & steering needed no vacuum reservoir.

My only "need" for a vacuum signal is because I like to have a vacuum gauge permanently installed.

Z.
Agree.

The reason manufacturers of IR manifolds have an included hidden plenum to join all the runners together is it is easier and cheaper to cast it as part of the manifold. You can accomplish the same result with a Vacuum rail underneath if the manifold is not already equipped with a plenum.

As far as manifold vacuum operated accessories is concerned the plumbing mentioned above is more than adequate to supply power brakes, HVAC vacuum motors, a map sensor etc.
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