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  • Ford 460 jet boat question

    Since it does not look like we will be racing outboards on the west coast this year, I have been working on my 1979 Jetster 460 jet boat. Totally restored it, new paint, interior etc. Friend and I installed a new 460 long block in boat last year, finally got it so it runs perfectly....will do well over 60, idles great. My question is this: at idle, around 700 rpm or so, it is not pumping enough water thru the system to keep motor cool. I have been told you cant install a thermostat on a jet boat....how do I keep some water in the block at idle? Any help would be appreciated.

  • #2
    Most likely would have to install a separate water pump to keep the engine cool at idle. I’m not totally familiar with boat jet systems but if they are anything like jetski’s etc they require engagement from the impeller to send cooling water into the motor. That long block you put it in, hope it was a marine engine. Car engines won’t last long in a boat. The mains in marine blocks have thicker main webs so as to be able to hold up to the higher sustained rpm’s of marine applications.

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    • #3
      Region 9 is planning on a race at Lk. Minden in late Aug. Dave, so your wrong about West Coast APBA racing. Just region 10 called it early. Oh and dont forget the AOF race in Idaho that Region 10 APBA members are heading to in a few weeks.

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      • #4
        700rpms at idle for a jet boat is too low.....bump it up to 900
        Daren

        ​DSH/750ccmh/850ccmh

        Team Darneille


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        • #5
          Daren: thanx for the advice. I bumped

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          • #6
            Daren: thanx for the advice. I bumped the idle up to 900 and it runs at around 190 temp. Plugs still look a little pale...any advice there? It has a Holley 600 cfm marine carb....don't know if that makes any difference.

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            • #7
              Rejet, no different than any other engine. May have to change the power valve, is it a 2 stage power valve? In my experience with Holley they are a pain in the ass even though they dominate the rod scene.

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              • #8
                Not sure if its a 2 stage power valve or not. The block and crank came out of a motorhome, was told it has a beefier lower end then standard. I run the thing pretty easy.....will try and bring it to a region 10 race next year.

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                • #9
                  600 Holley is too small for a 460......should have a 750
                  Daren

                  ​DSH/750ccmh/850ccmh

                  Team Darneille


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