Announcement

Collapse
No announcement yet.

Total Timming SBC 350

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

    Total Timming SBC 350

    Two questions here. 1: Suggestions on total advance for sbc 350 in front of Volvo 280. 2: Suggestions on advance degree stop ( 21, 25, 28 etc, degrees. I'm installing MSD marine distributor.

    #2
    Dished or non-dished pistons? Carb or EFI with knock sensor? Dished pistons setup for quench will allow move ignition advance.
    1997 Maxum 2400 SCR 5.7LX Bravo II

    Mike

    Comment


      #3
      Agree some details would be helpful, including type of cylinder head being used and the size of the boat. Id say don't stray from the original (OEM) timing curve unless you've added a LCQE type piston and run higher octane fuel.
      Dave
      Edmonds, WA
      "THE FIX"
      '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
      (.030 over-Vortec top end-part closed cooled)
      The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
      Misc. projects thread
      https://www.baylinerownersclub.org/f...56-gctid789773

      Comment


        #4
        I'll try to keep this short as not to confuse anyone or have them scratch their heads. I'm dealing with a non-vortec sbc 5.7 4 bolt main, in a 1984 Bayliner Trophy 2459. I have no history on the boat or engine. I'm certain it is not the original engine because the valve covers that were used when the engine change was made identified a 5.0 305 sbc. I've since had the engine rebuilt. To my knowledge, the heads are 75cc, and the pistons were dish. I can put my scope down in the cylinder and see which ones I have. Until then, I'm open to suggestions on a timing curve. I just need a starting point. The MSD I'm installing comes preset with a 21 degree advance stop. I have the ability to change the stop degrees of the advance. With my initial tdc at 8, that will put my total timing at 29. If I'm correct, the OEM curve should be 30 - 35 total. I hope I didn't loose anyone here.

        Comment


        • builderdude
          builderdude commented
          Editing a comment
          Since you've had the engine rebuilt perhaps you can get some details from the builder such as cylinder head cc volume, piston type/size, & camshaft profile.
          As a side note:
          If shes raw water cooled, some marine specific parts would be required.

        #5
        Since you have dished pistons I wouldn't go any more than 34 degrees total. I like to stay at 32 total just for safety's sake.
        1997 Maxum 2400 SCR 5.7LX Bravo II

        Mike

        Comment


        • builderdude
          builderdude commented
          Editing a comment
          Agree 32 max. Non of the mErcruiser TB modules go any higher then that

        #6
        That's my thought too. I forgot to mention the engine is not EFI. It's old school. Where would you recommend the advance to start? somewhere between 1000/3000rpm or higher and quick or gradual? I give thanks for the suggestions and any future suggestions.

        Comment


          #7
          Initial timing of 8* should be at idle and the advance should increase from there in a linear curve until full adcance is achieved.
          1997 Maxum 2400 SCR 5.7LX Bravo II

          Mike

          Comment


            #8
            Initial advance can start around 750- 1000 rpm. My mercruiser 5.7 has the TB IV 24 module installed, see its timing curve below. Click image for larger version

Name:	image.png
Views:	1
Size:	493.3 KB
ID:	417841
            Dave
            Edmonds, WA
            "THE FIX"
            '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
            (.030 over-Vortec top end-part closed cooled)
            The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
            Misc. projects thread
            https://www.baylinerownersclub.org/f...56-gctid789773

            Comment


              #9
              Here's another bit of TB IV data if it'll help.
              Click image for larger version

Name:	image.jpeg
Views:	1
Size:	125.1 KB
ID:	417872
              Dave
              Edmonds, WA
              "THE FIX"
              '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
              (.030 over-Vortec top end-part closed cooled)
              The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
              Misc. projects thread
              https://www.baylinerownersclub.org/f...56-gctid789773

              Comment


                #10
                I would like to give thanks to all who provided suggestions concerning this post (timing). I would like to start a new thread here. I have noticed the lower gear housing is leaking. I thinking the seal and/or O-rings my need attention. The outdrive is a 1984 280 without trim. My question is: can the O-rings and seal be replaced with removing the entire outdrive. When looking at the repair manual, it seems the prop shaft could be removed gaining access to the O-rings and seal allowing replacement of them. I'm open for suggestions before attempting this service. Thank you.

                Comment

                Working...
                X