Official 390 E.C. Thread

Discussion in 'Classic Sea Rays' started by electricaldoctor, May 19, 2009.

  1. cmn1882

    cmn1882 Member

    43
    May 9, 2012
    Pine Harbor Marina - Soddy Daisy, TN
    1989 Sea Ray 390 Express Cruiser
    7.4L Gassers
    Hey guys...I have lightly searched for information on oil changes, but cannot find anything for our boat specifically. My boat has 7.4 gassers. What is the oil capacity? What oil are you guys running? Any particular brand of oil filter or fuel/water seperator that is preferred? I thank you in advance for any information.
     
  2. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    You're oil capacity should be 6 quarts with filter. To be safe put in 5, run the engine for a minute, shut down and check level. Add another quart if needed. You're old flat tappet engines require oil with ZDDP additive to protect the camshaft and lifters. I use Valvoline VR1 racing oil it is available in different "weights". I use K&N oil filters because they have a heavy duty shell and quality internal components. I installed Racor fuel filters when I got my boat 9 years ago. Make sure you get the "inboard" engine Racors with the metal fuel bowl.
     
  3. cmn1882

    cmn1882 Member

    43
    May 9, 2012
    Pine Harbor Marina - Soddy Daisy, TN
    1989 Sea Ray 390 Express Cruiser
    7.4L Gassers
    Thanks! I used the VR-1 for my Land Rover! I will use this set up on my next oil change.
     
  4. cmn1882

    cmn1882 Member

    43
    May 9, 2012
    Pine Harbor Marina - Soddy Daisy, TN
    1989 Sea Ray 390 Express Cruiser
    7.4L Gassers
    What is best RPM to run for cruising? MPG/Distance?
     
  5. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 EC
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin 546s Plotter
    454 Crusaders
    Your best cruise rpm will depend on whether or not your boat has had the typical 390EC trim tab modification that has been discussed many time in this thread. The purpose of the modification is to get the bow of the boat "over the hump" to obtain good visibility and have the boat run at the best "attitude" which results in the best ride and efficiency. I have made the extensive modifications to my trim tab system and my 390 will come up on plane with full fuel and up to 10 adults on board at 2800 rpm and about 20 mph.

    As far as mpg don't expect anything spectacular. Once you pass hull speed "aprox. 8mph" you will get aprox. .6mpg. It doesn't matter if you are going 12mph or 25mph those 454s will net you about .6mpg. I know this because I have Garmin GFS10 flow meters. At 6-7 mph that will improve to aprox. 1-1.1 mpg. Stop judging your boat and usage based on mpg. The cost of fuel is one of the cheapest parts of your boat ownership.
     

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