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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
If you hook up the vacuum/boost gauge to a vacuum port in the throttle body that is below the butterfly but on the side of the throttle shaft where the butterfly is going downward as you open it and crossing over the little hole in the TB throat you will get a venturi effect from the extreme velocity of the air rushing by as the butterfly passes over that hole and your vacuum reading will be higher than what is actually in the manifold and inaccurate.

At full throttle there is probably some venturi effect in any port or hole anywhere in the throttle body due to the air velocity rushing over it.

Take your vacuum/boost signal from the intake manifold somewhere away from the throttle body for a more accurate reading.

The brake booster hose is already there and perfect.
T into it, or get one of the plastic brake booster check valves that has a hose connection for a boost/vacuum gauge.

North Hollywood Speedometer "NHS" probably has them.
Old 05-28-2008, 06:18 PM
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