454 Exhaust Crossover Restrictor Plates Question
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454 Exhaust Crossover Restrictor Plates Question

  1. #1
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    Default 454 Exhaust Crossover Restrictor Plates Question

    I have a 1988 Mercruiser 454 with the stock intake and quadrajet cab and wondering if anyone knows for sure if you should install the exhaust gas restrictor plates in one or both sides of the intake manifold gaskets? The Mercruiser manual I have doesn't say anything more than it must use an intake gasket with an opening if it does have an automatic choke.

    I also boat in Arizona so we don't have much cold weather but will have plenty of 100+ degree days of boating.

    The old rebuilt block did not have them installed but they also put a Gen 5 head on a Mark IV block so I don't trust much of what they did.

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  3. #2
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    It looks like Fel Pro says they should be installed in their instructions.
    https://fme-cat.com/livedocs/982M(1-2).pdf

  4. #3
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    But then looking up the correct Fel Pro gasket they say the restrictors should be in there. And I finally found a picture of the correct Mercruiser gasket on Ebay and sure enough it has restrictor holes on both sides. So I take it that they should have the restrictor plates in there.
    Click image for larger version. 

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    So now I have to decide if it's safe to run it as is with the full port open or if we have to tear the intake back off and install a gasket set with the restrictor plates in them or install the Mercruiser gasket set.

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  6. #4
    Some guy obnoxious001's Avatar
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    Given the choice, I would prefer to block the heat riser openings, but I would not take it back apart to change if you did not.

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