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150 merc 1984 black max exhaust ports??

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  • 150 merc 1984 black max exhaust ports??

    my 150 has the thru prop hub exhaust, two just below lower powerhead cowl as usual. but it also has 3 each side of cavitation plate pointing down of course? none of my other merc have had these 6 ? or any other i see. any idea why i have them, sounds like i`ve got headers on it when coming off plane from high speed. perfect hole shape and looks like factory paint so i don`t think they are homemade.

  • #2
    Re: 150 merc 1984 black max exhaust ports??

    Merc Lower units have gratings just above the AV plate. Normally these discharge only water. Perhaps the exhaust seal in the top of the gearcase is missing or out of position. You might drop the LU and see.


    • #3
      Re: 150 merc 1984 black max exhaust ports??

      I've seen people drill the midsection out just as you describe for better hole shot...does the same thing PVS would do on a prop or over the hub exhaust...without causing any chance for blowout of the prop. Doesn't help top end any from what I've heard..but will help your hole shot..and yes...its LOUD...sounds kind of mean though...the baffle is probably taken out of it too...this is all okay but can lead to premature wearing out of the midsection. They are probably about 1" in diameter??
      "I'm your Huckleberry..." "You ain't no Daisy..."