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  1. 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
  2. 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.
  3. 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...
  4. 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...
  5. 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...
  6. 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...
  7. 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.
  8. Scott06

    4.3 Mercruiser Crank, No Start

    I think that is a repower serial number which has a different parts look up. @Fun Times I think knows where to get the parts breakdown
  9. Scott06

    4.3 Mercruiser Crank, No Start

    check with a volt meter if you have 12 v on + post of coil ... Do you have that? Electrical drawings are below.to test you can jumper 12v from battery to positive side of coil if you get spark solve why you dont have 12 v there by chasing it down with a volt meter.
  10. Scott06

    Building a '93 Caravelle 1750 Classic Bowrider

    the 2.5 and 3.0 had ratings ranging from 110-140 hp over the years ( like 60's thru now). Throw in that the ratings went from flywheel to prop hp at some point it is overly complicated. When my folks bought the 91 sea ray it had options of 125 hp (3.0L) and the 3.0LX at 135 hp. If I recall...
  11. Scott06

    4.3 Mercruiser Crank, No Start

    The fuel pump gets power from the starter during cranking, which bypasses the oil pressure switch during cranking, mechanic should have know that. If the Oil switch was bad Fuel pump would run during cranking, engine would run for a short time until fuel bowl is empty, cranking again would...
  12. Scott06

    Mercruiser 3.0L Overheated What to Look Out For?

    200 is not that hot for that time period you are probably fine. If your compression is still good just keep an eye out for milk in the oil that would be evidence of water intrusion. When you do the impeller use OEM merc parts as they last longer. Not sure if this is a Gen one or Gen 2 drive...
  13. Scott06

    Mercruiser 5.7 EFI Water in Oil

    Yes they are 3/8-16 threads. 33 ft pounds is correct
  14. Scott06

    Mercruiser 5.7 EFI Water in Oil

    Yes I know that but when I have done the same it seems like some water sits on top of gaskets. As others have stated make sure surfaces are flat, use the OEM metal/fiber (not paper) gaskets, and a little perfect seal/permatex #3 on the bolt threads so they come out down the road.
  15. Scott06

    Building a '93 Caravelle 1750 Classic Bowrider

    Yeah there is an issue with power given the combo you state. If the tach is accurate prop down until you get rpms up to 4400 or so. I believe Barr makes an adapter for the head and manifold mismatch you have...
  16. Scott06

    mercarb power valve

    Its for enrichment at high throttle openings. Allows more fuel to run parallel to main jets . https://www.carburetor-parts.com/Power-Circuit-Mercarb_ep_2061.html
  17. Scott06

    Mercruiser 5.7 EFI Water in Oil

    Pretty sure that is a casting line to op doesnt look like water is streaking down exhaust side. Think water in bottom came when you took it apart
  18. Scott06

    Building a '93 Caravelle 1750 Classic Bowrider

    Would question if your tach is accurate if only getting 3500 rpm with a 15p, unless you have the wrong gear ratio drive for your engine. what is max rpm for this motor ? You should be up around 4400 or more rpm. I also found the same thing with a couple different 21, 22, 23" props- you hit a...
  19. Scott06

    Mercruiser 5.7 EFI Water in Oil

    this is a leakdown tester. It outs a known pressure of compressed air into a cylinder and measures the residual pressure the cylinder holds. Leakdown is measured as a % leakdown . <5% is great, start getting over 10% you have an issue. What I was mentioning is just putting compressed air in...
  20. Scott06

    Mercruiser 5.7 EFI Water in Oil

    New compression with an accurate gauge is 150 psi. When its starts getting below 115 give or take, or you have a big difference between cylinders you have issues. If low a leak down test can be used to pinpoint where you are loosing it. Can also put compressed air in the cylinder and see if...
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