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  1. #1

    Default 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Bought a 1978 Bellboy 24 ft cabin cruiser with 240 hp Ford 5.7 liter motor. Most of sterndrive missing but Id rather replace it with a Mercruiser outdrive. Is that possible? I have almost no money in the boat but really like the style.

  2. #2
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    SEI makes a conversion unit

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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Ayuh,..... A '78 would be a Stringer drive,..... A 5.7l would be a Chevy motor,......

    A mercruiser swap would mean ya need abunch of glass work, 'n a complete mercruiser driveline, from pulleys to prop,.....
    Any Grease is Better,... Than No grease at All....

  4. #4
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Quote Originally Posted by Kevndeb619 View Post
    Bought a 1978 Bellboy 24 ft cabin cruiser with 240 hp Ford 5.7 liter motor. Most of sterndrive missing but Id rather replace it with a Mercruiser outdrive. Is that possible? I have almost no money in the boat but really like the style.
    As Bill said, in 1978 this would be an OMC Stringer Drive. The conversion kits (Merc, SEI or Volvo Penta SX) are for the OMC Cobra drive.

    Since there is no need for one, many of the Stringer Drive boats did not incorporate a structural transom.
    If you retro-fit this boat with a Stern Drive, the transom must become structural, and the opening in the transom will need to be reduced.

    If you do this, I would strongly suggest going with an AQ series Volvo Penta, and steer clear of the Merc A drive and/or the SEI A drive copy.

    With an AQ series, you will have:
    ......main suspension fork and pivot tube geometry (no gimbal system)
    ......no gimbal bearing and/or no periodic gimbal bearing replacement
    ......fixed PDS geometry between engine and universal drive shaft (no annual engine alignment required)
    ......all steel Borg Warner drive coupler (no rubber hub drive coupler that may fail)
    ......NO thru prop exhaust (less back pressure on the system)
    ......super easy and quick drive shaft bellows replacement
    ......no shift cable bellows
    ......smooth cone clutch gear engagement (no dog clutch, no ESA, no SI or SA, etc)
    ......engine mounted seawater pump...... very easy to service



    With the Merc A drive, you will have:
    ......gimbal system suspension
    ......periodic gimbal bearing replacement
    ......annual drive coupler alignment
    ......rubber hubbed drive coupler (prone to failure if alignment is not up to snuff)
    ......thru prop exhaust
    ......clunky dog clutch gear engagement
    ......a shift assist system that can be problematic and fussy to adjust
    ......more timely and labor intensive drive shaft bellows replacement
    ......shift cable bellows that requires periodic replacement
    ......lower gear unit located seawater pump.... lower unit must be removed to service






    .

    Last edited by RicardoMarine; 08-19-2019 at 08:15 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  5. #5

    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    I really appreciate all the great responses! Time I have, fiberglass I have. Expertise in choosing a replacement drive I do NOT have.

  6. #6

    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    The engine is a Ford 351, if that makes any difference

  7. #7
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    ......................
    Quote Originally Posted by Kevndeb619 View Post
    I really appreciate all the great responses! Time I have, fiberglass I have. Expertise in choosing a replacement drive I do NOT have.
    I've owned and have worked on both Volvo Penta and Mercruiser, allowing me to experience the Merc A drive Dog Clutch and the related issues, and the less problem prone Volvo Penta Cone Clutch drives.
    I spent approx 24 years doing Volvo Penta AQ series engine and drive repair.

    In post #4, I have contrasted some of the aspects of both AQ series V/P and Merc A drive, including the
    Gimbal system geometry -vs- main suspension fork/pivot tube geometry.
    For me, the Volvo Penta AQ series would be my choice over that of the Merc A drive.



    Quote Originally Posted by Kevndeb619 View Post
    The engine is a Ford 351, if that makes any difference
    The Ford 5.8L is a candidate for the Volvo Penta AQ series, just as it would be for the Merc A drive.


    Either the Merc A or the AQ series V/P is going to require that you re-do the structural transom. In other words, the old OMC Stringer Drive transom "cut-out" (i.e., opening) will need to be in-filled and become structural.

    In a good used stern drive system, either one is going to cost about the same.
    Some people find that it is less expensive to find a donor boat for all of these parts...... perhaps one with a bad engine or a bad hull, etc.


    The Merc A drive will offer power trim.
    In order to have PT with the V/P system, you will need to go with a 290 or later.

    The AQ series V/P easily lends itself to the addition of the Duo Prop lower gear unit, whereas with the Merc you would need to do a more expensive and later year model B series drive in order to have the twin counter-rotating propeller system.


    Good luck, and we will be here if you have more questions.


    .
    Last edited by RicardoMarine; 08-20-2019 at 08:00 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  8. #8
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Quote Originally Posted by Kevndeb619 View Post
    The engine is a Ford 351, if that makes any difference
    Ayuh,..... Merc quit usin' Ford power back in the late '70s,.....

    That's why I said you'll need a Merc driveline, from pulleys to prop,......

    Find a rotten hull, with the driveline you want, then scrap the donor boat for it's driveline,.....

    That way, you'll have all the little expensive bits to do the job,......
    Any Grease is Better,... Than No grease at All....

  9. #9
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Merc quit usin' Ford power back in the late '70s,.....

    That's why I said you'll need a Merc drive train, from pulleys to prop,......
    Or...... pick up a later year donor boat (with GM engine) and then find a flywheel cover that works with the Ford 5.8L

    If he goes with the AQ series and finds a GM engine donor boat, he'd need to do the same thing.

    example;

    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  10. #10
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Quote Originally Posted by RicardoMarine View Post
    Or...... pick up a later year donor boat (with GM engine) and then find a flywheel cover that works with the Ford 5.8L

    If he goes with the AQ series and finds a GM engine donor boat, he'd need to do the same thing.

    example;

    Ayuh,..... There are no Ford flywheel covers that'll work with a Merc, other than the old MC-1 drives, which also went outa production in the late '70s,.....

    The rear motor mounts got narrower when the MC-1 went away,.....
    Any Grease is Better,... Than No grease at All....

  11. #11

    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Quote Originally Posted by RicardoMarine View Post
    ......................

    , allowing me to experience the Merc A drive Dog Clutch and the related issues, and the less problem prone Volvo Penta Cone Clutch drives.


    .
    related issues?? Only about the most available and popular drive out there, parts readily available. To OP I wouldn't discount using a merc alpha drive if you find a good engine and drive in a donor boat.

    Im going on 30 years between two alpha drives (two boats) with no significant issues. Yes it's a dog clutch that clunks... simple design.

    Rick you had posted about resurfacing or lapping VP cone clutches recently, how is that less trouble prone? Never had a dog clutch apart and I do plenty of watersports and WOT.

    Again wouldn't discount a alpha drive if you find one to tear out

  12. #12
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    ......................
    Quote Originally Posted by bondo View Post
    . There are no Ford flywheel covers that'll work with a Merc, other than the old MC-1 drives, which also went out of production in the late '70s,..... The rear motor mounts got narrower when the MC-1 went away,.....
    For me, that would be one more reason for going with the AQ series Volvo Penta.

    However, and on that topic, if he did go with a Merc A drive, could he not find an early Ford 5.8L flywheel cover along with the correct inner transom plate that would allow the rear engine mounts to work?

    .

    Quote Originally Posted by Dieter View Post
    Quote Originally Posted by Rick
    ....................., allowing me to experience the Merc A drive Dog Clutch and the related issues, and the less problem prone Volvo Penta Cone Clutch drives.

    related issues??
    Yes.... related issues, such as the SI or SA finicky adjustment, the less effective lower unit seawater pump, the rubber hub drive coupler and the required annual engine/coupler alignment (due to geometry between the rear engine mounts and gimbal bearing axis), not to mention the Gimbal suspension system!

    Only about the most available and popular drive out there, parts readily available.
    Yes, and that is a good thing.

    To OP I wouldn't discount using a merc alpha drive if you find a good engine and drive in a donor boat.
    From what I read in posts #1 and #5, the OP has a good 5.8L engine that he'd like to re-use.

    Im going on 30 years between two alpha drives (two boats) with no significant issues. Yes it's a dog clutch that clunks... simple design.
    I agree....... it is a simple design. Likewise with the AQ series V/P and with cone clutch gear engagement to boot.

    Rick you had posted about resurfacing or lapping VP cone clutches recently, how is that less trouble prone?
    Yes, I have posted many times on the topic of lapping the bronze sliding sleeve against the corresponding steel gear cups.
    It is a rare requirement, and can easily be done during a transmission re-seal.


    Never had a dog clutch apart and I do plenty of water sports and WOT.
    Please understand that I am glad to see that any Merc A drive owner is having good luck with his/her drive.
    I would never wish otherwise!


    Again wouldn't discount a alpha drive if you find one to tear out
    One of the beauties of a forum like this, is that we are free to voice our own opinions and share our experiences.

    Having owned and worked on both has allowed me to make what I'd consider to be a fair and comparative evaluation for myself.

    I would encourage those who Foo Foo the AQ series V/P to actually own one before doing so.
    If you have not owned an AQ series V/P, yet you Foo Foo them, I would ask: is that really fair?




    Here's an updated version of my last two paragraphs in post #4;

    With an AQ series, you will have:
    ......main suspension fork and pivot tube geometry (no gimbal system)
    ......no gimbal bearing and/or no periodic gimbal bearing replacement
    ......fixed PDS geometry between engine and universal drive shaft (no annual engine alignment required)
    ......all steel Borg Warner drive coupler (no rubber hub drive coupler that may fail)
    ......NO thru prop exhaust (less back pressure on the system)
    ..... larger rubber prop hub due to NO thru prop exhaust
    ......super easy and quick drive shaft bellows replacement
    ......no shift cable bellows
    ......smooth cone clutch gear engagement (no dog clutch, no ESA, no SI or SA, etc)
    ......engine mounted seawater pump...... very easy to service
    ..... easy addition of the twin-counter-rotating-propeller V/P Duo Prop lower gear unit.



    With the Merc A drive, you will have:
    ......gimbal system suspension
    ......periodic gimbal bearing replacement
    ......annual drive coupler alignment
    ......rubber hubbed drive coupler (prone to failure if alignment is not up to snuff)
    ......thru prop exhaust
    ......smaller rubber prop hub due to thru prop exhaust
    ......clunky dog clutch gear engagement
    ......a shift assist system that can be problematic and fussy to adjust
    ......more timely and labor intensive drive shaft bellows replacement
    ......shift cable bellows that requires periodic replacement
    ......lower gear unit located seawater pump.... (lower unit must be removed to service)
    ......no option of adding a
    twin-counter-rotating-propeller lower gear unit.



    Bottom line..... we are all here to help the OP with his decision.
    I'm simply sharing what I believe to be his best option given my experiences.




    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  13. #13
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    One more thing;

    Look at the used market for certain and popular late 80s early 90s model boat that was OEM equipped with OMC, Merc A drive, and Volvo Penta. Or...... just look at the Merc A drive and Volvo Penta boats.
    Must be the same year/model boat in order to be a fair comparison.


    The OMC drive boat listing will seldom mention OMC, and it will typically bring the least amount of sales money.
    The Merc A drive boat listing will mention Merc, and it will typically bring more money than the OMC equivalent.
    The Volvo Penta drive boat will definitely mention Volvo Penta, and will typically bring a higher sales amount over that of either the OMC or the Merc A boat.

    This is not speculation.

    My friend owns/operates a Marine Salvage yard.
    He buys/sells boats and boat parts.
    Out here in our area, there is a fair and equal share of older OMC, Merc and Volvo Penta systems.
    With regard to used stern drive parts:

    His #1 profitable sales is OMC.
    His #2 profitable sales is Merc.
    His #3 and least profitable sales is Volvo Penta.


    Ask yourself why?


    .
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  14. #14
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    However, and on that topic, if he did go with a Merc A drive, could he not find an early Ford 5.8L flywheel cover along with the correct inner transom plate that would allow the rear engine mounts to work?
    Ayuh,..... 'bout anything is possible, but I've never tried it, 'n it could lead to many unknown "Gotcha's",.......

    To OP I wouldn't discount using a merc alpha drive if you find a good engine and drive in a donor boat.
    From what I read in posts #1 and #5, the OP has a good 5.8L engine that he'd like to re-use.
    Ford has been outa the marine market for many years,....
    Parts are hard to find, 'n stupidly expensive,.....

    Sell the runnin' Ford, to pay for the runnin' rotten donor boat, with Chevy power, which is King of the marine power market,.....
    Any Grease is Better,... Than No grease at All....

  15. #15

    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Rick I'm not "foo fooing" the AQ simply pointing out the issues you state about a mercruiser alpha drive don't match mine or other life long boaters I know that have alpha drives so I think your last sentence is a bit out of line.

    So as as you said simply pointing options for th OP, I think we would be wrong to dissuade the OP from using merc products as any modern merc or vp would put him in a better position than the stringer he has.

    I tihnk Bondo is on the right track find a soup to nuts tear out that uses relatively modern Chevy based engine and modern drive regardless of VIP or merc is the best approach vs piecing together. In the end OP will do what

  16. #16
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    .......................
    Quote Originally Posted by Dieter View Post
    Rick I'm not "foo fooing" the AQ simply pointing out the issues you state about a mercruiser alpha drive don't match mine or other life long boaters I know that have alpha drives so I think your last sentence is a bit out of line.
    Understood.
    And as said earlier.... "
    One of the beauties of a forum like this, is that we are free to voice our own opinions and share our experiences."

    So as as you said simply pointing options for th OP, I think we would be wrong to dissuade the OP from using merc products as any modern merc or vp would put him in a better position than the stringer he has.
    No disagreement there. I'm sure that the Stringer Drive helped OMC head for the eventual bankruptcy.

    I tihnk Bondo is on the right track find a soup to nuts tear out that uses relatively modern Chevy based engine and modern drive regardless of VIP or merc is the best approach vs piecing together.

    Did you mean V/P or Merc?
    If so, that is fair enough.

    I'm hoping that the OP take heed of my two updated paragraphs in post #12.
    I would be willing to help him with any questions regarding parts and/or procedures!


    Bottom line..... we are all here to help the OP with his decision. I'm simply sharing what I believe to be his best option given my experiences...... and I may as well add, my dislike of any Dog Clutch stern drive!
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  17. #17

    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Putting all the "passion" and pooh poohing aside, my mailman and I agree that this project is a prime candidate for an outboard conversion. "Non structural transom"?

  18. #18
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Quote Originally Posted by mcomm View Post
    Putting all the "passion" and pooh poohing aside, my mailman and I agree that this project is a prime candidate for an outboard conversion. "Non structural transom"?
    I'm not sure if that's a question or sarcasm.

    None the less and FYI......., some of the boat builders did not incorporate a structural transom for the OMC "stringer" drives.
    The hull shell is there, and the large rubber boot attaches to it, but there was no transom core build up as per what an actual stern drive or an outboard engine would require!





    .
    Last edited by RicardoMarine; 08-22-2019 at 07:22 PM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

  19. #19
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    Default Re: 1978 OMC 240 HP Ford 5.7 liter-can I replace OMC outdrive with Mercruiser?

    Example


    Click image for larger version. 

Name:	transom structural vs non-structural.jpg 
Views:	9 
Size:	53.5 KB 
ID:	21552
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP drives

    "Intellectual growth should commence at birth and cease only at death." Albert Einstein

    Please... no PMs! Post your questions on the forum.

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