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Continuation of WOT problems. I need some ideas please.-gctid382276

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    Continuation of WOT problems. I need some ideas please.-gctid382276

    For those just now reading this thread, please don't offer any more solutions for the fix. The problem was found, the problem has been fixed.:getsmilie

    I know it's a long thread but I think it has lots of good information.:arr


    I am really banging my head on this problem and I can't think of anything else to do so please if anyone can think of anything, I would really appreciate any and all input.

    Here is what I have;

    1980 Victoria 2750 Flybridge and the bottom of boat is clean.

    Chevy 350, VP280 OD with a 290 DP lower running B-3's props in good condition.

    Here's a recap of the problem;

    3000-3150 RPM is about all I can get with the engine loaded and top speed is about 19 mph GPS tops. It's burning 16-18 GPH according to the flow scan. I get no more engine response (rpm) from the throttle after about 2/3rds advanced, although the throttle goes all the way to the stop and the engine doesn't cough, backfire or run rough. It just stops increasing RPM after it reaches Approx 3000RPM. By the way the trim tabs a fully down.

    Here is what I have done so far;

    I pulled the pickup tube and checked the screen, anti siphon valve, and tank vent. All checked good. Gas is fresh. Fuel flow is plentiful through the new spin on 10 micron filter, through the new electric fuel pump to the carb. Pulled the inlet screen/filter going into the carb and it is clear. Carb is a new rottenchester 4 barrel 650 cfm marine carb and the flame arrester is clean. Spark plugs look good so I'm thinking burn is good. I have full throw on the carb/throttle linkage.

    Just installed a complete new Mallory marine distributor. Complete means; distributor, cap, rotor, ignition module. Timing is set to 8*BTDC at 650 RPM. TAT is Approx 30*@3000 rpm. Rick I know this will make you crazy. I did not index the wheel but I can watch the timing advance using the light. Also the Mallory is a brand new unit out of the box and it is performing exactly like the old pertronix distributor and since TAT is a function of the flyweights and mechanics of the unit.so that's my theory. Am I wrong?

    Went through the new plug wires to ensure firing order is correct and installed a new flame thrower coil.

    Did a few more items Rick (Bounty) suggested;

    I check the upper helm (an original analog tach) against the Flowscan digital in the main and found the old tach is running 400 rpm higher the digital. So does that mean I'm actually running 3400 rpm and 19 mph. I checked the back of the Flowscan to make sure it's set for V-8.

    Opened the engine lid, removed the flame arrester and had the admiral run the engine up. Carb secondaries start to open at aprox. 23-2400 rpm and are fully open by aprox 2800 rpm based on the digital tach.

    #2
    You have done everything you should do to gain rpms except one thing.

    The props. It sure sounds like you are over propped.

    If you were running out of fuel I think you could feel and hear that.

    Are you bow high at wot? Sounds like you don't have enough power to get over the top.

    Doug
    Started boating 1955
    Number of boats owned 32
    Bayliners
    2655
    2755
    2850
    3870 presently owned
    Favorite boat. Toss up. 46' Chris Craft, 3870 Bayliner

    Comment


      #3
      For those just now reading this thread, please read the entire 32 page/300+ posts thread.

      There was a problem, it was found, and there is a conclusion at the end of this.


      Wayne, Doug may be right! You may be over-propped.

      Also, with your TT's all the way IN, this is creating some drag. You should not need to be full-in once out of the hole....., IMO.

      As for ignition timing, if you are comfortable with the way that you checked this, you should be A-OK.

      Don S. over on iBoats once owned a Victoria F/B w/ the Duo Prop.... and he may still own it.

      I suppose you could ask over there and see what props he used.

      .
      Rick E. Gresham, Oregon
      2850 Bounty Sedan Flybridge model
      Twin 280 HP 5.7's w/ Closed Cooling
      Volvo Penta DuoProp Drives
      Kohler 4 CZ Gen Set

      Comment


        #4
        2850Bounty wrote:
        Wayne, Doug may be right! You may be over-propped.

        Also, with your TT's all the way IN, this is creating some drag. You should not need to be full-in once out of the hole....., IMO.

        As for ignition timing, if you are comfortable with the way that you checked this, you should be A-OK.

        Don S. over on iBoats once owned a Victoria F/B w/ the Duo Prop.... and he may still own it.

        I suppose you could ask over there and see what props he used.

        .
        Go over to the dark side. surely you jest.:arr

        Comment


          #5
          dmcb wrote:
          You have done everything you should do to gain rpms except one thing.

          The props. It sure sounds like you are over propped.

          If you were running out of fuel I think you could feel and hear that.

          Are you bow high at wot? Sounds like you don't have enough power to get over the top.

          Doug
          Well I'm not sure there is such a thing, but I'm not as on plane as I used to be. I always needed tabs to get there, but I used to be able to trim them up and now I just fall off if I do.

          Funny you should mention that and as a matter of fact I took my spare set of B-3's in yesterday to have them re-pitched to B-2's. I won't get them back until next Wednesday. The Prop shop thinks I will get around 300 rpm on a duoprop pitch change. It sure would be nice if that's all I needed to get me the rest of the way there, but I'm a little skeptical because I'm about 1600 rpm out from WOT.

          Comment


            #6
            Fish-a-Palooza wrote:
            ............ I'm a little skeptical because I'm about 1600 rpm out from WOT.
            My wife tells me that often if we have a disagreement!
            Rick E. Gresham, Oregon
            2850 Bounty Sedan Flybridge model
            Twin 280 HP 5.7's w/ Closed Cooling
            Volvo Penta DuoProp Drives
            Kohler 4 CZ Gen Set

            Comment


              #7
              2850Bounty wrote:
              My wife tells me that often if we have a disagreement!
              Rick,

              You have got to stop watching the new Ashley Judd series and the wife will come around.

              LOL

              Comment


                #8
                Cliff, you have a great memory! I'll give that a try!
                Rick E. Gresham, Oregon
                2850 Bounty Sedan Flybridge model
                Twin 280 HP 5.7's w/ Closed Cooling
                Volvo Penta DuoProp Drives
                Kohler 4 CZ Gen Set

                Comment


                  #9
                  2850Bounty wrote:
                  My wife tells me that often if we have a disagreement!
                  Rick,

                  Do you argue about what WOT stands for.

                  She probably thinks Woman on Top!!!!!!

                  Comment


                    #10
                    Do you have any blowby (check breather lines attached to the spark arrestor)? What are your compression readings? Have you checked each and every spark plug to make sure it's firing? Have you checked the valve lash?

                    You have done the easy stuff. Sounds to me like you perhaps have a dead cylinder...sometimes it's hard to pick up the difference in sound. I had a smooth running low power engine...I checked it and had a out of whack reading...turns out there was major detonation damage in 2 cylinders. I swear you couldn't hear it running rough.

                    Chay

                    Comment


                      #11
                      Is it the right carb? is the carb bad?

                      Plug wire on wrong?

                      I think this is low? I burn at WOT 29 GPH (ItÔÇÖs burning 16-18 GPH according to the flow scan.)

                      I think your over proped but it still should turn more rpm's

                      Fish-a-Palooza wrote:


                      Here's a recap of the problem;

                      3000-3150 RPM is about all I can get with the engine loaded and top speed is about 19 mph GPS tops. ItÔÇÖs burning 16-18 GPH according to the flow scan.

                      Here is what I have done so far;

                      Carb is a new rottenchester 4 barrel 650 cfm marine carb

                      .

                      Comment


                        #12
                        It could be a bad spark plug wire. Two years ago I had my boat in the shop twice trying to figure out why it wouldn't reach WOT specs. Finally we changed the spark plug wires and that was it. The engine was not firing on all 8 cylinders at high rpm. It would run on all 8 at low rpm, but the bad wire would not carry enough current to fire the charge under heavy load.

                        Cost me over a boat buck for the shop time and other parts we threw at the problem before we solved it.

                        Comment


                          #13
                          Put a timing light on each spark plug wire, should tell if not firing, I would guess props, but you could run a compression check, also check each spark plug and see if the color of the insulators are the same.
                          Pat says: DO-IT-RIGHT THE FIRST TIME!

                          Bayliner 3870 "ALASKA33)
                          Twin 350 GM power
                          Located in Seward, AK
                          Retired marine surveyor

                          Comment


                            #14
                            cfoss wrote:
                            Do you have any blowby (check breather lines attached to the spark arrestor)? What are your compression readings? Have you checked each and every spark plug to make sure it's firing? Have you checked the valve lash?

                            [COLOR]"#0000FF" wrote:
                            No blowby, Last I checked compression was good. I have not rechecked valves clearances[/COLOR]

                            You have done the easy stuff. Sounds to me like you perhaps have a dead cylinder...sometimes it's hard to pick up the difference in sound. I had a smooth running low power engine...I checked it and had a out of whack reading...turns out there was major detonation damage in 2 cylinders. I swear you couldn't hear it running rough.Chay

                            [COLOR]"#0000FF" wrote:
                            I'll be checking it out.[/COLOR]
                            gary1p wrote:
                            Is it the right carb? is the carb bad? [COLOR]"#0000FF" wrote:
                            Carb is the correct one.[/COLOR]

                            Plug wire on wrong? [COLOR]"#0000FF" wrote:
                            No went through them 3 times.[/COLOR]

                            I think this is low? I burn at WOT 29 GPH (It's burning 16-18 GPH according to the flow scan.) [COLOR]"#0000FF" wrote:
                            [/COLOR][COLOR]"#0000FF" wrote:
                            What are you burning at 3000 rpm??? [/COLOR]

                            I think your over proped but it still should turn more rpm's [COLOR]"#0000FF" wrote:
                            We'll see, could be.[/COLOR]
                            2859er wrote:
                            It could be a bad spark plug wire. Two years ago I had my boat in the shop twice trying to figure out why it wouldn't reach WOT specs. Finally we changed the spark plug wires and that was it. The engine was not firing on all 8 cylinders at high rpm. It would run on all 8 at low rpm, but the bad wire would not carry enough current to fire the charge under heavy load [COLOR]"#0000FF" wrote:
                            I'll check it out.[/COLOR]
                            boatworkfl wrote:
                            Put a timing light on each spark plug wire, should tell if not firing, I would guess props, but you could run a compression check, also check each spark plug and see if the color of the insulators are the same[COLOR]"#0000FF" wrote:
                            [/COLOR][COLOR]"#0000FF" wrote:
                            Good idea! I'll do that[/COLOR].
                            Good stuff keep it coming, I know the answer is here and it's not Model Victoria specific.

                            Comment


                              #15
                              Maybe you're hauling 500 pounds of water logged transom and stringers.
                              " WET EVER "
                              1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
                              mmsi 338108404
                              mmsi 338124956
                              "I started with nothing and still have most of it left"

                              Comment

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