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Thread: Vacuum Port - List 50463

  1. #1

    Default Vacuum Port - List 50463

    I apologize in advance for any stupid questions. I'm new to working on carbs. I have a 1988 Holley List 50463 (some people say it's a marine 4160). I would attach a photo, but I can't get that to work on my iPad.
    I'm attempting to connect a vacuum gauge to set my idle. The only port I can find on the carb is on top right (driver's side), if looking from front that has a small rubber boot over the port. I connect my gauge to that port and get no readings at all. The 4160s seem to have ports just above idle screw on passenger side. Can anyone tell me where I can hook the vacuum gauge to set the idle screws. I'm at a loss. (If you want I can email you pic of carb since I can't upload.) Thanks.

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  3. #3


    Look around the base plate underneath the fuel bowl in the front/rear. There are only two types of vacuum. Ported and manifold. Manifold is what you are looking for, and it will pull air until you bump the throttle and it will momentarily reduce and then come back. Port vacuum at idle will not produce any vacuum until you press and hold the throttle, and then it will start producing vacuum. I looked around for a diagram on that model number, and can't seem to find any. Just search the carb around the base plate and you should find them.

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