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What is initial timing on 4.3GL & can I advance it to improve performance?

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  • #31
    Originally posted by Lou C View Post
    the answer is NO simply put.
    This. Too many unknowns. Lou's got hands -on experience with these engines. Although they share many components with a 350 SBC, there are enough items unique to the smaller version to make a broad generalization.

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    • #32
      Well I think with all the uncertainty I am just going to leave it alone...I might check it to see where it is set at the very least but its too cold for that right now...wish I had indoor storage! I just would like to know for sure if 87 octane is acceptable...I am guessing the carb motor has no knock sensor.

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      • #33
        87 octane (R+M/2) is what is in your manual.... your good to go.
        Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

        1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

        Past Boats
        1970 Wooster Hellion - Merc 9.8
        2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
        1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

        What’s behind you doesn’t matter.Enzo Ferrari

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        • #34
          Originally posted by USA_boater View Post
          Well I think with all the uncertainty I am just going to leave it alone...I might check it to see where it is set at the very least but its too cold for that right now...wish I had indoor storage! I just would like to know for sure if 87 octane is acceptable...I am guessing the carb motor has no knock sensor.
          Probably not. Plus, you usually don't hear detonation "at full chat". It's better to be 2 degrees too retarded than 2 degrees too advanced.

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          • #35
            Agreed and it is a good idea to pull your plugs out after a run, once a year to check the color of the center insulator. The window inside your engine. If they are nice and light brown or grey you are good. Blistered white is no good.
            And while we are talking about timing and fuel octane the other factor in your inboard engine longevity, is correct prop pitch. You want that engine to be able to reach its specified RPM at WOT, if your rpms are too low, that engine will labor to pull the boat up on plane every time with the resultant overheating of exhaust valves and eventual low compression. When I got my boat it had a 14.5x19 on it and only got 4200 rpm. I went first to a 15x17 that got me to about 4600 and am going to try a 15.5x15 next to see how close to 5,000 that gets me.
            1988 Four Winns 200 Horizon
            4.3 OMC Cobra

            98 Jeep Grand Cherokee 4.0 Selectrac
            07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

            "While air doesn't freeze....rust never sleeps"

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            • #36
              Originally posted by Lou C View Post
              Agreed and it is a good idea to pull your plugs out after a run, once a year to check the color of the center insulator. The window inside your engine. If they are nice and light brown or grey you are good. Blistered white is no good.
              And while we are talking about timing and fuel octane the other factor in your inboard engine longevity, is correct prop pitch. You want that engine to be able to reach its specified RPM at WOT, if your rpms are too low, that engine will labor to pull the boat up on plane every time with the resultant overheating of exhaust valves and eventual low compression. When I got my boat it had a 14.5x19 on it and only got 4200 rpm. I went first to a 15x17 that got me to about 4600 and am going to try a 15.5x15 next to see how close to 5,000 that gets me.
              Great point Lou...on my list...the boat has an aluminum 3 blade but the PO gave me an un-used 4-blade with the boat when I bought it...He told me he had work done on the prop/skeg from a shallow ramp accident but I have no idea if it is still using the OEM Volvo prop w/ correct pitch...The tach doesn't work though so I have to figure that out first. I can tell you "on principle" I was planning to get a whale tail but since the boat gets on plane just fine I dropped that plan...hopefully that speaks to using the correct pitch prop when RPM is unknown.

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              • #37
                Well I'd say your first priority when you start next season, is to have a working tach, because otherwise you will never know, if the prop is right or not. And while people worry about plugs, carbs, converting points ignition to electronic, etc, the MOST important adjustment so to speak on a marine engine is the RIGHT PROP. Without it reaching the proper wide open throttle rpm, the life of the engine will be shortened, because a low WOT rpm is like making a truck with a 2.73:1 rear axle pull a heavy trailer, starting in second gear. In other words NOT GOOD!
                1988 Four Winns 200 Horizon
                4.3 OMC Cobra

                98 Jeep Grand Cherokee 4.0 Selectrac
                07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                "While air doesn't freeze....rust never sleeps"

                Comment


                • #38
                  Well by the way it gets on plane and the way it screams (sound not MPH) at WOT, I'd say it is giving all it has...BUT, I've only seen 43mph (full gas, people in boat other than me, gear, etc.) and I figured this 4.3GL should be capable to run 45-50MPH??? The lack of MPH is one clue that makes we wonder about the prop. I need to GPS the speed next season to know for sure.

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                  • #39
                    Originally posted by USA_boater View Post
                    Well by the way it gets on plane and the way it screams (sound not MPH) at WOT, I'd say it is giving all it has...BUT, I've only seen 43mph (full gas, people in boat other than me, gear, etc.) and I figured this 4.3GL should be capable to run 45-50MPH??? The lack of MPH is one clue that makes we wonder about the prop. I need to GPS the speed next season to know for sure.
                    you may need more motor.
                    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

                    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

                    Past Boats
                    1970 Wooster Hellion - Merc 9.8
                    2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
                    1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

                    What’s behind you doesn’t matter.Enzo Ferrari

                    Comment


                    • #40
                      I found some fast facts guide by Four Winns from 2004 online and it said the 4.3GL in this boat yields 47-50mph so either my speedo is off, the guide is off, or the prop is off?

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                      • #41
                        Sign up today
                        Without knowing what your actual WOT rpm is, hard to say. However, if you fix the tach and can see that you get your max rpm then that's all its got. Your max rpm is much more important than your MPH. My boat is a 20' H-200 and I think its supposed to do 42 or so but it has been bottom painted so many times that it is SLOW.....nothing much I can do but have the bottom blasted and start over again.
                        1988 Four Winns 200 Horizon
                        4.3 OMC Cobra

                        98 Jeep Grand Cherokee 4.0 Selectrac
                        07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                        "While air doesn't freeze....rust never sleeps"

                        Comment

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