Carb vacuum port ID
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==Ported vacuum== | ==Ported vacuum== | ||
| − | A ported vacuum source | + | A ported vacuum source will register vacuum only when the throttle blades are opened past idle. At idle there should be no vacuum or very nearly so, depending on how far the primary throttle blades are opened to allow the engine to idle. Engines having big cams and a low vacuum signal at idle will often have the primary throttle blades opened too far, causing a vacuum signal at the ported vacuum port(s). This can cause "nozzle drip", a harsh odor of exhaust, and a poor idle quality. This can be fixed by supplying the engine with bypass idle air sufficient to allow the throttle blades to be returned to a normal position. More on this <nowiki>[link to carb article]</nowiki>. |
===Uses for ported vacuum=== | ===Uses for ported vacuum=== | ||
====Vacuum advance==== | ====Vacuum advance==== | ||
| − | One use is for the distributor vacuum advance. There is always debate on which type of vacuum for the vacuum advance is "best". The simple truth of the matter is there are reasons for either to be used, depending on the situation. While ported vacuum for the vacuum advance is often thought to be for "emissions" applications, there are sound reasons for a performance engine to use ported vacuum. | + | One use is for the distributor vacuum advance. There is always debate on which type of vacuum for the vacuum advance is "best". The simple truth of the matter is there are reasons for either to be used, depending on the situation. While ported vacuum for the vacuum advance is often thought to be for "emissions" applications, in certain cases there are sound reasons for a performance engine to use ported vacuum. |
==Manifold vacuum== | ==Manifold vacuum== | ||
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===Uses for manifold vacuum=== | ===Uses for manifold vacuum=== | ||
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| + | ====Vacuum advance==== | ||
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====PCV vacuum ports==== | ====PCV vacuum ports==== | ||
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