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  1. Scott06

    Propeller Pitch Selection

    What is the drive ratio? I think with a boat that light will need a 1.47 drive and probably a 21" pitch or maybe a tad more pitch. As outlined you want to find a prop shop like Hills or I think Prop MD does pitch exchange. Just need to find someone who will work with you to try before you buy...
  2. Scott06

    Trim pump wiring acting opposite

    I think the 4 th one is for trailer button you have two up buttons trim and trailer trim works through the limit switch trailer always works regardless of drive position
  3. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    When reading plugs they show what you last ran which was likely idle to read them you need to run at what ever rpm you want to look at afr then cut it off immediately and pull a plug
  4. Scott06

    4.3 Mercruiser Crank, No Start

    You will not get any power to fuel pump if engine is not running and ignition is on unless you jump out the oil pressure switch. The purple yellow from starter is what supplies power during cranking. If you think is fuel related dump some gas down carb and crank it over.if you have ignition it...
  5. Scott06

    Winterization

    If you got full amount of water out of the 5 drain plugs then you are good I would drain the -50 af you put in and leave it dry given the temps u state If you ask two guys on here about af or no af you will get 3 different answers … I personally don’t use it and have never had any corrosion...
  6. Scott06

    Mercruiser Vacuum Gauge

    Would Anni correct pitch show lower or higher vacuum
  7. Scott06

    Mercruiser 5.7 260 EFI - Water Temp Fluctuations

    None of this is really concerning assuming u are running a 160 thermostat if you are running a 140 and these are accurate temps the something is amiss 5 degrees coming off plane is not an issue If you don’t know when last replaced do the impellers and use OEM merc parts the gen 2 impeller...
  8. Scott06

    Mercruiser Vacuum Gauge

    Pontiac used to offer a vacuum gauge in the 60s it is hooked to manifold vacuum with a small tube. Generally it is used for economy indication as vac drops with throttle opening. Not sure what place it has on a boat as part throttle cruise doesn’t exist in a marine application like on a car at...
  9. Scott06

    Mercruiser 5.7 EFI Water in Oil

    If u need to refog it just unscrew add more oil and use it next year will not hurt the filter
  10. Scott06

    Drive destroyed

    Has your friend checked with his insurance ? Might be covered it was for my friends bravo 3
  11. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    On the bottom right of the graph it reports max hp as 244 which matches the graph. You have to download and blow up the pic to seeit. If you pd for 360 tell them to show u where on the dyno graph it is. The power falls way off at higher rpm likely due to the carb used it ran out of air. It said...
  12. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    According to this it made 244 hp, and torque dropped way off at higher rpm. Stock merc 383 is 340 hp so comparatively something is really wrong. Roy means his sister had a 24 ft Sea Ray in the 80's for 10 years.... You can google the tuner companies give them your cam grind and they can set...
  13. Scott06

    Mercruiser 5.7 EFI Water in Oil

    Why do you have to trash the filter? Let the fuel clean it out and run through it in the spring
  14. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    Is this the same 555 ECM ? https://www.cpperformance.com/p-81018-ecmpcm-555-custom-calibration.aspx I think these guys list offer a 555 to MEFI conversion
  15. Scott06

    1990 Mercruiser 4.3 Same As???

    Not always. Im sure some higher end motors are 4 bolt but plain jane 3.0/4.3/5.0 are not 4 bolt.
  16. Scott06

    1990 Mercruiser 4.3 Same As???

    Oil pan is likely marine specific too. You may be able to find the GM number for this vs getting a Merc one As mentioned above fuel, electrical, and exhaust are marine specific. Long Block wise the only diff between truck & Industrial and Marine is generally marine head gaskets and brass or...
  17. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    Ok so wasn't a full set up (or power) dyno. Not unusal to use the dyno owned carb as the builder wont have all accessories like fuel pump etc that go on car. Most guys have known carbs so they wont waste time chasing owner provided carb issue or ruin a motor running lean. He used the 2 bbl...
  18. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    Retuning this for the 383 is not an option. You are running this lean for sure in an environment that is pron e to detonation. Check your plugs before you detonate this thing to death, which no engine builder will cover. What was the hp/torque curve and AFR from the dyno ? Should have made at...
  19. Scott06

    Need RPM’s on 383MPI 1970 SeaRay 24’ project

    I believe that MPI just does fuel mapping in open loop off the throttle setting- doesn't have O2 sensors in the exhaust system to give feedback to ECM? If so you likely are running lean would check your plugs ASAP and not lean on it too much. I think you need to find a way to reflash or...
  20. Scott06

    Mercruiser 5.7 EFI Water in Oil

    Great you may have to do another oil change in spring to get all the milk out.
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