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    7.4 crank mount raw water pump info needed

    I want to replace the combo belt driven raw water/fuel pump on my 1997 2859 7.4. I am going to install the holley red electric marine fuel pump and oil press safety switch and use the Johnson fb6 raw water pump.

    What I am not sure about is the routing of the hose from the outlet side of the pump to the PS cooler. Is there a molded hose that might make this easy for my application? It's going to have to make some crazy bends to get to where it has to go.

    Can I use the OEM water intake from the transom or is this too restrictive for this pump? I plan on converting to a thru hull at a later date but would like to use it for a year or 2 this way if possible.

    Do I need to use the bracket to hold the pump from spinning or will the wire reinforced hoses give enough support?

    Any info on parts or pieces that I might need would be appreciated!

    Thanks!

    Doug
    1995 2859 -extensively rebuilt/restored 2016/17
    496 big block - Bravo ll leg
    The Doghouse
    Prince George BC

    #2
    ........
    Originally posted by sketch96 View Post
    I want to replace the combo belt driven raw water/fuel pump on my 1997 2859 7.4. I am going to install the holley red electric marine fuel pump and oil press safety switch and use the Johnson fb6 raw water pump.
    Doug, first make sure that you have enough space in front of the harmonic balancer to accomodate the length of the F6B-9 and also space to remove the cover in order to R&R the impeller.
    If all is OK, you will be glad that you did this!

    Benefits:
    No more belt tension side load on the bearings. These crankshaft pumps go forever without issues.
    Easy impeller removal during winter layup. Remove the impeller and it will be good for the next season.


    What I am not sure about is the routing of the hose from the outlet side of the pump to the PS cooler. Is there a molded hose that might make this easy for my application? It's going to have to make some crazy bends to get to where it has to go.
    You'll need to be creative.
    Keep in mind that on the suction side, the hose must be fairly collapse proof, which doesn't necessarily mean that it must be wire reinforced.
    On the supply side, it does not need to be!


    Can I use the OEM water intake from the transom or is this too restrictive for this pump?
    Given that both pumps would be similar in volume, it should be no more restrictive than it was before with the belt driven pump.

    I plan on converting to a thru hull at a later date but would like to use it for a year or 2 this way if possible.
    It should be very possible.

    Do I need to use the bracket to hold the pump from spinning or will the wire reinforced hoses give enough support?
    Doug, great question.
    While I can't tell you that it is 100% goof proof, I've been running two F5B-9s without the torque arms for years.
    My suction/supply hoses have done a great job at preventing any pump body rotation.
    IMO, those pumps would need to completely freeze up in order to realize a problem.


    Any info on parts or pieces that I might need would be appreciated!
    The F5B-9 and F6B-9 mounting flanges both require two alignment dowels that have been stamped into the pulley during manufacturing.
    The pump mounting flange itself requires three fasteners.
    While the flange can be mounted in one of three ways, only one is correct, and it will be determined by the two raised dowels.

    By the way, the correct pulley is nothing more than a GM Automotive pulley.

    Click image for larger version  Name:	Johnson F5B 9 and F6B 9 pumps 2.jpg Views:	2 Size:	466.1 KB ID:	599939

    Since these pumps will work for either rotation engines, here's some info regarding a Std LH rotation engine -vs- a REV RH rotation engine.

    Click image for larger version  Name:	johnson crank pump inlet outlet explained 2 .jpg Views:	2 Size:	102.3 KB ID:	599940


    If your pulley does not have the two raised areas, another option would be 3 custom made bushings that will allow the three bolt pattern to do the aligning.
    NOTE: two types of bushings are shown here.

    Click image for larger version  Name:	Crankshaft pump conversion bushings .jpg Views:	2 Size:	284.3 KB ID:	599938



    Rick E. Gresham, Oregon
    2850 Bounty Sedan Flybridge model
    Twin 280 HP 5.7's w/ Closed Cooling
    Volvo Penta DuoProp Drives
    Kohler 4 CZ Gen Set

    Comment


      #3
      I use clear wire reinforced hose, takes the mystery out of water flow.




      " WET EVER "
      1989 2459 TROPHY OFFSHORE 5.8L COBRA / SX
      mmsi 338108404
      mmsi 338124956
      "I started with nothing and still have most of it left"

      Comment


        #4
        Thanks for the info and pics very much appreciated!! So one question about the indexing - do I need to purchase a different bottom pulley for the 1997 gen VI 7.4 with the v belts? Do i need to buy the bushings you mention? If so where can I find them?

        Looking forward to this modification. give me some extra room to access that side of the motor. No way I can fit down there right now.
        Doug
        1995 2859 -extensively rebuilt/restored 2016/17
        496 big block - Bravo ll leg
        The Doghouse
        Prince George BC

        Comment


          #5
          ..........
          Originally posted by sketch96 View Post
          Thanks for the info and pics very much appreciated!!
          You are welcome!

          So one question about the indexing - do I need to purchase a different bottom pulley for the 1997 gen VI 7.4 with the v belts?
          Look at the pulley shown in my first image (lower right hand corner).
          Then look at your pulley and see if it has the same 2 raised dowels stamped into it.


          Do i need to buy the bushings you mention? If so where can I find them?
          If your pulley does not have the raised dowels, you have two options:
          ...... replace the pulley with one that does (it is a GM part).
          ..... have the bushings custom made by a machinist (see my last image).

          If you go with the bushings, the cap screws should have a smooth shank at the area where they penetrate the bushings.
          (see my last image)


          Also note that I show options for two different length bushings.
          .... Non-Specific long length stands the flange away from the pulley, moving the pump forward.
          .... Short length keeps the flange tight to the pulley.

          The bushings should not penetrate the pump's mounting flange any greater than the thickness of the flange..... in fact, they should be shy by .020"/.030" or so.
          (we want the cap screws to securely clamp the mounting flange, and not the bushings only).

          Edit:

          MFG. GM Part #: 91038811

          Fits SBC, and I believe that it may fit the BBC as well.




          Rick E. Gresham, Oregon
          2850 Bounty Sedan Flybridge model
          Twin 280 HP 5.7's w/ Closed Cooling
          Volvo Penta DuoProp Drives
          Kohler 4 CZ Gen Set

          Comment


            #6
            Thanks so much - I'm planning on this exact mod to mine this winter, I look forward to seeing pictures of your progress!
            1998 Bayliner 2858
            7.4L MPI / Bravo III
            Harbour Village Marina - Kenmore WA

            Comment


              #7
              So it looks like I have a different style lower pulley. Cast. The one in the pic above definitely wont work in my application I dont think. I need the outer groove for the PS so it needs to have the same depth from the dampener. The middle groove was the raw water pump that I want to remove, and the inner groove is for the alt.

              Any ideas??
              Doug
              1995 2859 -extensively rebuilt/restored 2016/17
              496 big block - Bravo ll leg
              The Doghouse
              Prince George BC

              Comment


                #8
                Same cast aluminum pulley I have on my sbc, what’s with the crank bolt? Is that a bbc thing?
                question: why do I see a idler pulley for a serpentine belt in your pic?
                Click image for larger version  Name:	82B4ABCD-2572-41CE-A93B-C45985C8AF5C.jpeg Views:	0 Size:	3.16 MB ID:	600182
                Dave
                Edmonds, WA
                "THE FIX"
                '93 2556
                Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                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
                  Originally posted by builderdude View Post
                  question: why do I see a idler pulley for a serpentine belt in your pic?
                  I noticed that also, Dave.

                  Originally posted by sketch96 View Post
                  So it looks like I have a different style lower pulley. Cast. The one in the pic above definitely wont work in my application I dont think.
                  I need the outer groove for the PS so it needs to have the same depth from the dampener. The middle groove was the raw water pump that I want to remove, and the inner groove is for the alt.

                  Any ideas??
                  Doug, I think that in your scenario, you will need to have the 3 bushings made that will hold the mounting flange out a bit.
                  Or..... see if there's a stamped steel version of that same profile pulley.



                  Keep in mind that had they limited themselves to thinking within the box, Wilbur and Orville
                  would have never flown!

                  Rick E. Gresham, Oregon
                  2850 Bounty Sedan Flybridge model
                  Twin 280 HP 5.7's w/ Closed Cooling
                  Volvo Penta DuoProp Drives
                  Kohler 4 CZ Gen Set

                  Comment


                    #10
                    Same idler I had on my last BBC with v belt. Seem to work fine. Smooth face. Would love to get rid of it and all the brackets and the belt.

                    I'm looking for a replacement lower pulley. I have found a billett aluminum pulley that might work. None have the dowel that I have found so far.

                    The bushings I'm guessing are something you can not buy?
                    Doug
                    1995 2859 -extensively rebuilt/restored 2016/17
                    496 big block - Bravo ll leg
                    The Doghouse
                    Prince George BC

                    Comment


                      #11
                      Never knew v belts used any type of idler or tensioning pulley. What belt does it ride against?
                      😳🤔
                      Dave
                      Edmonds, WA
                      "THE FIX"
                      '93 2556
                      Carbureted 383 Vortec-Bravo II 2.0:1 18 1/4x19 P

                      The rebuild of my 2556 https://www.baylinerownersclub.org/f...76?view=thread
                      Misc. projects thread
                      https://www.baylinerownersclub.org/f...56-gctid789773

                      Comment


                        #12
                        Raw water pump/fuel pump.
                        Doug
                        1995 2859 -extensively rebuilt/restored 2016/17
                        496 big block - Bravo ll leg
                        The Doghouse
                        Prince George BC

                        Comment


                          #13
                          Damn Rick
                          That looks like my work bench in the background. I told you we need to patent those spacers!
                          Nice edits on the pictures by the way.
                          I had those spacers made by a buddy with a machine shop. I think I paid 50 bucks for the set.
                          Where the bushings fit into the pump is a couple of thousands over so they fit tight.. Somewhere i have a post on building them.
                          I don't remember the dimensions.
                          As for plumbing good luck!!
                          I've been stuck trying to plumb my motor for months. Mine is a little more complicated in that I'm trying to mount the heat exchanger in the rear. I've looked at silicone hose, steal braided hose,custom bent steal tubing. I am still at a loss for how to get it done. Without it looking like Frankenstein. Im almost to the point of buying a Hosfield tube bender and trying to make them myself.Any suggestions I'm all ears.
                          1992 2452
                          5.0 alpha1 gen2

                          Comment


                            #14
                            Has anyone removed the PS pump? That would leave me only needing the alt belt and a single groove pulley. Just not sure how heavy the steering would feel with out the assist.
                            Doug
                            1995 2859 -extensively rebuilt/restored 2016/17
                            496 big block - Bravo ll leg
                            The Doghouse
                            Prince George BC

                            Comment


                              #15
                              Truth in posting:

                              The spacers shown are not mine.
                              I believe that they were from a photo posted earlier by lineman.
                              I used them for my examples only!
                              Rick E. Gresham, Oregon
                              2850 Bounty Sedan Flybridge model
                              Twin 280 HP 5.7's w/ Closed Cooling
                              Volvo Penta DuoProp Drives
                              Kohler 4 CZ Gen Set

                              Comment

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