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Thread: Vacuum port on 1850-2 vacuum secondary housing?

  1. #1

    Default Vacuum port on 1850-2 vacuum secondary housing?

    I'm restoring a pair of Holley 1850-2 carburetors that came on a tunnel ram intake. They both have a vacuum port on the top of the vacuum secondary assemblies on the side of each carb. There are also ports on the metering blocks. How do I hook up hoses to these extra ports?

  2. #2


    The vacuum ports on the secondary pods are to be joined together. This balances both secondaries pods, so that they open at the same time when the throttle is floored. The ports on the side of the metering blocks is for timed vacuum for distributor vacuum advance. If you have a full mechanical advance distributor, block both ports. If you have a stock type or performance distributor with a vacuum advance pod, and will be using vacuum advance, connect this hose to one of the carbs (metering block) & block the other.

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