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Discussion Starter #1
Im working on getting my engine timed and tuned properly.
I have an older Holley double pumper 4777-2

The port that was originally used to run to the vacuum advance is up on the side of the carb, my only other port is down low in front of the carb.

WHen the engine is at idle the side port has zero vacuum on the gauge but my front port shows around 15 on the gauge.
 

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Im working on getting my engine timed and tuned properly.
I have an older Holley double pumper 4777-2

The port that was originally used to run to the vacuum advance is up on the side of the carb, my only other port is down low in front of the carb.

WHen the engine is at idle the side port has zero vacuum on the gauge but my front port shows around 15 on the gauge.
The port up on the side that has no vacuum at idle is ported vacuum, used for vacuum advance from the factory on EGR equipped (pollution control vehicles which you probably don't have and most likely don't want). The port down low that has vacuum at idle is manifold vacuum and that's the one that you should run to your vacuum advance canister.
 

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Discussion Starter #3
Thank you! I figured that would make more sense but wanted to check. Thanks!
 

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