Need help

Discussion in 'Boating and Boat Rigging' started by Smitty03, Apr 24, 2020.

  1. Smitty03

    Smitty03

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    I know this isn’t probably the right form, but I have a 24ft crestliner Sabre with 4.3l in it , can anyone or does anyone know what prop should be on it? The boat purrs like a kitten but I only can get 3900 rpms out of it an top speed of 30mph. thanks smitty
     
    textox likes this.
  2. kroppe

    kroppe

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    Smitty03, there is a boat technical forum on this site. Maybe a mod will move this thread to that section.

    Has the boat ever run properly in your ownership?
     

  3. Smitty03

    Smitty03

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    Boat runs greats, just can’t get over 3900 rpms,
     
  4. Smitty03

    Smitty03

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    I never had it above 4000 rpms
     
  5. CHASINEYES

    CHASINEYES

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    Have you made sure your carb butterfly is opening completely?
     
  6. Smitty03

    Smitty03

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    I have not that is what we are checking this weekend, I can’t believe the carb would be not opening up on how it runs, but I honestly don’t know that’s why I’m asking
     
  7. talltails

    talltails

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    I did have the same issue on my boat years ago and basically just had to change the pitch on the prop. Is it a little slow to get up on plane , that would also suggest a pitch problem. Good Luck
     
  8. Smitty03

    Smitty03

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    It takes a few to get up on plane had a 15x15 then I switched to a 14 1/2 by 17 right now an it is alittle better but not where it should be
     
  9. talltails

    talltails

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    First off I am not a mechanic but to IMHO the switch you made kind of nullified itself. The smaller dia. would increase the RPM's but the higher pitch would take more of a bite so it would lower the RPM's . I would think that you would want to stay with a 15 inch Dia. but lower the pitch # to a 13 or even a 12 if available. Again I am not a pro just trying to help. Good Luck
     
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  10. Far Beyond Driven

    Far Beyond Driven

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    For more speed you want a higher pitch. For a better hole shot you want a lower pitch.

    You have a 200-205 hp engine in a fairly light boat. It should not struggle to climb up and certainly should hit more than 30. I'm guessing the engine isn't making full power, or maybe something really weird like a small leak and your foam is soaking wet.

    What is the supposed WOT for your motor? Mine is like 4800 but will run higher than that. 4.3 is just a 350 sans two cylinders so it should be about the same.

    I've got a glass 22' with a 350. 19" trolls great, nice hole shot, tops out at 41 and can over rev the engine.

    21" comes out of the hole slower, trolls ok, and can still over rev the engine but can run 47.

    23" wallows out of the hole, can't troll slow enough, makes docking interesting. Can't hit WOT but will run well into the fifties.
     
  11. Smitty03

    Smitty03

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    Thanks for all the responses I was afraid someone was going to mention soaking wet foam! That crossed my mind a few times
     
  12. anagranite

    anagranite

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    I have an older 222 sportcraft that I repowered with a 4.3l. I'm not sure of the hp but it's carbureted. 190hp I think. I switched props several times and finally found the one I like. It jumps on plane rather quickly, tops out in the upper 30s, and it will hit the rev limiter if you really try. Here is a picture. 20200425_094949.jpg 20200425_095002.jpg
     
  13. kroppe

    kroppe

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    @Smitty03 What is the complete history of this boat? The description of the situation leaves many questions in my mind. This is like a used vehicle. Symptoms present themselves, and normally are explainable if the full history is known.

    What is the full history of your ownership of this boat? Do you know the history of the boat prior to your ownership?

    You have a 24' Sabre that won't run past 3900-4000 rpm, correct?

    You are asking about prop pitch. What diagnostic information leads to the prop being the cause or the solution?

    Carb (throttle) opening is something to check, as mentioned. There could be an issue at the engine (carb) or with the throttle cable mechanism along its entire length up to the helm (shifter).

    Heavy hull (soaked foam) is another suggestion. You need to find a way to affirmatively rule this in or rule it out.

    Restricted air intake is easy to check.

    What about the fuel system? What condition are the rubber supply lines? Is the fuel tank vent functioning properly? Is/are the fuel filter(s) new in the past few years?
     
    bad dog and Doghouse 5 like this.
  14. Smitty03

    Smitty03

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    I had a lot of work done by a well know boat mechanic in port Sanilac, he put a electronic ignition every year the fuel filter an all the filters get changed, the boat idles an runs great just can’t get above 4000 rpms, the throttle from 3/4 to full doesn’t do anything rpms don’t move or anything, I’m checking to see if water logged today an that the choke is working,
     
  15. kroppe

    kroppe

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    It sounds like the engine idles OK.

    The engine can't get over 4,000 rpm.

    Check for throttle plate restriction or throttle cable/mechanism binding from the carburetor to the helm.

    Are you 100% sure the fuel filters have been changed?

    What about air/induction restriction?