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Contemplating custom building a 5.7 for my 2359.

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    Contemplating custom building a 5.7 for my 2359.

    Getting geared up to repower my 2001 2359 in next year. Its got a 5.0 carbed vortec engine right now which runs well.Alpha gen 2 drive with 1.82 or is it 1.84 gearing. I cruise at 42 litres per hour and 26 mph,3700 rpm.

    1.Id like a bit more hole shot power,the 5.0 struggles with a good load but will always get there with a little trimtab assistance

    2.Id like a bit better fuel economy ,certainly no worse.

    3.I do a fair amount of fishing maybe 50 hours trolling per year at around 900 rpm the 5.0 does this really sweet Id like to retain that.

    4.I dont want to overstress my Alpha drive. A bit more pwer than present 220 would be nice but not 300 or anything like that.

    I ve been reading Bounty and others posts on building a SBC with Q/E pistons and the idea really appeals to me. Ive rebuilt maybe 20 engines so feel confident in my ability to see this thru.But there are some questions:mainly:
    1. are my 4 objectives above attainable?
    2.And what specs do I build to?Pistons cam heads mainly I guess.Which ones to get?
    3. I assume Id have to change to a mechanical or vacuum advance distributer to get the desired timing(from present TB4 system) ?
    4.What volume do I build for best results?5.7? 6.3? etc.
    5. Will my present mercarb do the job on the somewhat more powerful engine?I like the simplicity of this unit.I see mercury uses exactly the same carb on a 5.7.
    6.Would my present gearing suffice,and what rpm should i shoot for to cruise at say 26 mph. Im assuming Id at the very least have to upprop and aim for a lower cruise rpm but Im definitely not sure about all this.

    Thanks for all input

    #2
    The 5.7 is going to use more fuel than the 5.0. Getting better fuel economy and wanting more power are opposing desires. Now you can build an efficient 5.7 with the power you want but it will use a little more fuel. Never use a vacuum advance distributor in a boat, just doesn’t work as a boat is ran at a constant throttle position. The Alpha is good to 300 HP. It’s easy to build a 260 HP 5.0 with a 600cfm carb or a 260 HP 5.7 with 4bbl carb with the GM dished pistons that Bounty hates. The point of the nondished pistons is to get more advance and torque at lower rpms with minim risk of detonation. If you want to go this route you may want to consider an aftermarket distributor/ignition such a Mallory.
    1997 Maxum 2400 SCR 5.7LX Bravo II

    Mike

    Comment


      #3
      Mike, a SBC quench effect piston IS dished........ it just doesn’t have the dished area underneath the cylinder head’s quench surface!
      The purpose of more ignition advance (with a quench effect build) is to gain a better LPCP!
      That’s what makes torque!!!!

      Telstar, if you are custom building a SBC for Marine cruiser use, you definitely want to incorporate a Q/E into the combustion chamber.
      Even if you stay with the OEM ignition system, this build will still outperform a SBC built using the GM full dished pistons!

      .
      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


      • Nauti_Mike
        Nauti_Mike commented
        Editing a comment
        Yep I know that, guess I should have full dish is what you hate.

      #4
      IMO there’s no need to change the ignition system with your new build, your already running a TB 4 ignition so the choice of ignition module will dictate how aggressive the timing curve can or will be.
      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


      • Nauti_Mike
        Nauti_Mike commented
        Editing a comment
        The price of that new module would cover a complete Mallory system including wires and coil.

      • builderdude
        builderdude commented
        Editing a comment
        That’s true Mike, those modules can be $pendy. I wonder which one he’s running now.

      #5
      Originally posted by telstar1 View Post

      4.I dont want to overstress my Alpha drive. A bit more pwer than present 220 would be nice but not 300 or anything like that.


      Thanks for all input
      I don’t think you’ll notice a big difference if you keep the increase under 60hp. I went from a 2 barrel 5.0 in my 2252 to a 320hp 5.7 from michiganmotorz. Top speed went from 32mph to 42mph. Mileage went from less than 1mpg to 2mpg! The 5.7 came with a 4 barrel edelbrock.
      Esteban
      Huntington Beach, California
      2018 Element 16
      Currently looking for 32xx in South Florida
      Former Bayliners: 3218, 2859, 2252, 1952

      Comment


        #6
        're the more power more fuel thing I'm not planning on going any faster so wouldnt normally use that extra power.I'd just like that power for special events etc. Plus id assumably be able to cruise (same mph) at a lower rpm which i think is a route to better mileage?I've seen it posted somewhere that a good quench build should use less fuel. ??Not sure if by going to more displacement I somehow lose that advantage?maybe I should build a 5.0?
        're the ignition thing ;builderdude what do you mean by choice of module?are there a selection of tb4 modules with different timing curves?

        Comment


          #7
          Originally posted by telstar1 View Post
          're the more power more fuel thing I'm not planning on going any faster so wouldnt normally use that extra power.I'd just like that power for special events etc. Plus id assumably be able to cruise (same mph) at a lower rpm which i think is a route to better mileage?I've seen it posted somewhere that a good quench build should use less fuel. ??Not sure if by going to more displacement I somehow lose that advantage?maybe I should build a 5.0?
          're the ignition thing ;builderdude what do you mean by choice of module?are there a selection of tb4 modules with different timing curves?
          yep
          Click image for larger version

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          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


            #8
            Keep in mind that these advance curve numbers are minus BASE advance.
            Add BASE and you’ll see the actual advance numbers.
            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


              #9
              Did a bit more research found a machine shop in nanaimo that seems to talk the quench marine build language much like Ricks posts on the subject. Encouraging.i asked him about the low rpm fishing thing and he was not enthusiastic. Talked about the lugging effect of doing this below 800rpm being bad for an engine ( not necessarily just a q/e build).im confused on this. Given the nature of propeller curves it seems to me the load on an engine at low rpm is quite low and this would not constitute lugging at all.
              I've been fishing by idling my "big engine" for a lot of years without issues. Wonder if I'm missing something here?would this be somehow worse with a q/e engine?
              This fellow also recommended the 5.7 for better economy due to lower potential cruising rpm.
              oh yes I figured out my ignition system is tb5 .no knock sensor. That's how they set up the 5.0 carbed apparently.it does some smart stuff like advancing timing at cruise until no more rpms are gained. So says the om merc manual.

              Comment


              • Nauti_Mike
                Nauti_Mike commented
                Editing a comment
                Not sure I've seen a TBV that doesn't have a knock module with it and the knock sensor. The knock module mounts piggyback to the TBV module on the distributor.

              #10
              Like this were b is the knock module.

              Click image for larger version  Name:	TB V.JPG Views:	1 Size:	22.5 KB ID:	478894
              1997 Maxum 2400 SCR 5.7LX Bravo II

              Mike

              Comment


                #11
                .......................
                Originally posted by telstar1 View Post
                Did a bit more research found a machine shop in nanaimo that seems to talk the quench marine build language much like Ricks posts on the subject. Encouraging.
                Good!

                i asked him about the low rpm fishing thing and he was not enthusiastic.
                Please elaborate!

                Talked about the lugging effect of doing this below 800rpm being bad for an engine ( not necessarily just a q/e build).
                At 800 RPM, a Marine engine would NOT be lugging. That RPM would just barely move the propeller and the hull, and with little effort!

                im confused on this. Given the nature of propeller curves it seems to me the load on an engine at low rpm is quite low and this would not constitute lugging at all.
                Correct!

                I've been fishing by idling my "big engine" for a lot of years without issues. Wonder if I'm missing something here?
                would this be somehow worse with a q/e built engine?
                Absolutely NOT!


                This fellow also recommended the 5.7 for better economy due to lower potential cruising rpm.
                Which is it? a 5.7L over that of a 6.3L............ or a 5.7L over that of a 5.0L????

                I can tell you that a SBC Engine Quench Effect combustion chamber will always operate more efficiently.

                Please read what you can regarding the Quench Effect or Squish Effect pertaining to engines with a wedge shaped combustion chamber and also read what you can regarding the use of that stupid no good foolish GM Full Dished piston!
                Read Dennis Moore (SBC Marine Performance), Jeff Smith (Super Chevy), Larry Carly, John Erb (Chief Engineer KB Performance Pistons).
                DO NOT read articles by Grumpy of Grumpy's Garage, for example, or any articles written specifically for Hot Rod use!

                Here's a thread that I got involved in several years ago. Begin reading at post #7.
                http://www.marineengine.com/boat-for...V8-engine-swap


                oh yes I figured out my ignition system is tb5 .no knock sensor. That's how they set up the 5.0 carbed apparently.it does some smart stuff like advancing timing at cruise until no more rpms are gained. So says the om merc manual.
                Actually, the EST system delays the actual spark event, and then alters the delay as RPM increase............ but this is far too much to get into right now!

                When you build this fresh SBC Q/E engine, dial in your harmonic balancer to True #1 TDC. Your machine shop will perform a PPS procedure in order to do this. Please make sure that they DO!
                Also, take it further by marking the balancer off up to approx 35* BTDC.
                (I will explain later how this will be advantageous when looking at ignition advance.)

                Then as you are putting all of this info into order as to make sense of it, think of this as the desired end result.




                Click image for larger version  Name:	LPCP explained.jpg Views:	1 Size:	644.9 KB ID:	478908








                The link below will take you to the .GIF that I used for the above still image as to show you guys the LPCP.
                Note that the left side shows a wedge shaped combustion chamber (ignore the domed piston), whereas the right side shows a hemispherical combustion chamber.
                Either style chamber benefits from a correct LPCP.
                When building a SBC with a quench/squish effect, LPCP can now occur where it should occur!


                ​​​​​​http://www.hotrodsandhemis.com/mtr1.gif



                .
                Attached Files
                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


                  #12
                  'RE the no knock sensor I was sceptical myself but I definitely don't have one and when I look up my ser# range on mcparts .com , lo and behold a 5.0 with alpha does not have a knock sensor.
                  Rick I'm in awe of your detailed informative reply. A lot of info to digest.( I had already studied the marineeng posts you referred to.)The reference to a 5.7 was comparing to a 5.0.I had not seriously considered a 383 (although it does have an alluring sound to the name)Do you think Rick that a 383 would be the most fuel efficient?Worried about what all that torque would do to my alpha, or is there a solution to that I wonder?

                  Comment


                    #13
                    ............................

                    Originally posted by telstar1 View Post
                    'RE the no knock sensor I was sceptical myself but I definitely don't have one and when I look up my ser# range on mcparts .com , lo and behold a 5.0 with alpha does not have a knock sensor.

                    I would not be concerned about that.
                    The reason for the knock sensor is the GM full dished piston that is being used in a Marine Cruiser environment.
                    I won't go into detail.... but in order to fully understand this, you'd need to understand Detonation, what causes Detonation and what helps prevent it.

                    And by the way..... Detonation and Pre-ignition are two entirely different phenomena!

                    ​​​​​​
                    Rick I'm in awe of your detailed informative reply. A lot of info to digest.( I had already studied the marineengine.com posts you referred to.)
                    I'll take that as a compliment...... thank you.
                    I've been involved with the SBC for many many years..... starting in 1966 or so.



                    The reference to a 5.7 was comparing to a 5.0.I had not seriously considered a 383 (although it does have an alluring sound to the name)

                    Do you think Rick that a 383 would be the most fuel efficient?
                    A 6.3L SBC when built correctly would be awesome. However, the torque would more than likely exceed the A drive's ability.

                    Worried about what all that torque would do to my alpha, or is there a solution to that I wonder?
                    Yes... but not an inexpensive one!

                    A great solution would be a quench built 5.7L SBC or a quench built 6.3L SBC with a Volvo Penta DP-C1 stern drive.
                    5.7L w/ 1.95:1 gear set..... and the 6.3L w/ 1.78:1 gear set.

                    That would turn your boat into something that had been previously thought to be impossible.


                    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


                      #14
                      in your budget, you can plan to spend about 2/3 more to convert a 350 to a 383. there are no shortcuts to it and I would recommend that a vortec block be used (roller cam), or at the very least, convert the pre-vortec block to a roller cam and get the vortec heads...

                      some of the '86 to '96 blocks were roller cam, but not all of them.... and none before '96 have the vortec heads.


                      NU LIBERTE'
                      Salem, OR

                      1989 Bayliner 2556 Convertible
                      5.7 OMC Cobra - 15.5x11 prop
                      N2K equipped throughout..
                      2014 Ram 3500 crew cab, 6.7 Cummins
                      2007 M-3705 SLC weekend warrior, 5th wheel
                      '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
                      Heavy Equipment Repair and Specialty Welding

                      Comment


                      • 2850Bounty
                        2850Bounty commented
                        Editing a comment
                        I'm not sure that I agree with the 2/3 times more expensive to convert...........
                        However, I do agree that the crankshaft kit will be more expensive.
                        You will also need to clearance the cylinder block for the added stroke... and if you have this done, it will add costs.

                        Also, if you do use the Vortec cylinder heads, be sure to use a piston profile whereby the piston deck mirrors the Vortec quench surface.

                        Is it worth it? He!! yes!

                      • Centerline2
                        Centerline2 commented
                        Editing a comment
                        I wont entirely disagree.... but if one is doing most of the work themselves, rebuilding a running but tired 350 can be done for around $1800.... to convert it to a 383 where the machine work may be more intensive, and buying a $1700 rotating assembly, it adds up quick... I have $4100 into mine and I shopped hard for the best prices on quality parts, and did more of the work myself than most DIY'ers would be able to, or want to do....

                        to refresh an engine before it gets to the point of NEEDING to be rebuilt, it can be done for quite a bit less than $1800..... I suppose it depends on ones budget and level of quality they are after... i would stick with the cost at about 2/3 more and if it comes to less, buy a case of beer or two and celebrate.... it never hurts to over budget but its very painful to under budget, especially if one is on a timeline

                      #15
                      I think Ill forego the 383. With greatest of respect to Volvo drives which I do acknowledge as being very good, I just cannot afford one. Ive seen the bill for a set of props. Holy crap. Im still a bit worried about going backward on fuel economy buy upping to a 5.7. I wonder what the HP gain(from present 220) would be if I did a QE build on a 5.0 vortec? And the hp of say a QE 5.7 Vortec?Im not looking for much hp gain 20 or so would be nice,I am more concerned with fuel economy.
                      Thx for great replies interest and info.
                      BTW Rick it was intended as a compliment!

                      Comment


                      • Centerline2
                        Centerline2 commented
                        Editing a comment
                        doing the build correctly WILL greatly increase the efficiency of the engine, and in turn, increase the economy.

                        a lot of what can be done depends on what one is able to do themselves.... or, take out a bank loan and hire it done.

                        if the 5.0 is tired and needs rebuilding, rebuilding it would be the very cheapest way to go and leave you with the economy of a 5.0... better pistons could help, but then you are adding dollars to the build that might be better spent on rebuilding a 5.7 vortec..
                        if the 5.0 is not tired, then a tune up may be in order to get back any lost efficiency....

                        you could shop around for a 5.7 vortec (they can be found for as cheap as $250) then rebuild it "stock", but with the correct pistons and a carburetor instead of the TBI system, and you would be about $2000 if you did everything except the machine work yourself... and end up with 250-270hp.

                        its "my opinion" that unless one has no money to do anything more than get the boat running, its not reasonable to rebuild a 5.0 (305ci) when a 5.7 can be had so cheaply for rebuilding.. the cost of the parts are almost the same, but the hp gains are more than well worth the searching it takes to find a good donor/core engine.... yes it would cost a little more than rebuilding the 5.0, but we cant expect so much more for nothing

                        EVERYTHING we do to our boats pivots around the dollar.... the amount of dollars we have dictates what we will do to our boats.
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