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  1. #1
    Join Date
    Sep 2017
    Location
    New Bern, NC
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    4

    Default Rebuilding Mark IV's 454 cid with one counter rotating

    Hi to all; newly registered to site, following for awhile;

    I am thinking about rebuilding two 454 bare blocks, one to be counter rotating. (Then, when necessary swapping for the original iron in my boat.)

    My research has shown that the two engines are identical except for timing drive, seals, camshaft and of course firing order. What puzzles me is that one site lists a different crusader BLOCK part number. Since the cranks are the same, is their some oiling issue from rotating the crankshaft in the opposite direction. Does the crankshaft have to be drilled differently in the counter rotating engine? Since I am not tearing down the original beasts, I can't know this in advance of the rebuilds.

    Thanks to all for all the great information on this site, and any help appreciated.

    Cheers,

    Larry

    P.S. anyone with bare blocks suitable for rebuild, I am interested...

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    7,172

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Welcome Aboard!!

    I've done a few and never found any differences in the bare blocks. The rear main seals with the 'nubs' are oriented 'backwards' on the RH engines. The front seals nowadays are 'universal' and not rotation sensitive. The pistons also go in 'backwards on the RH engine. The standard build uses a four bolt main block.

    I'd suggest finding a factory service manual as it will spell out the differences if you are doing it. The other option would be to let the machinist assemble the block - just make sure they understand your application is marine.

  3. #3
    Join Date
    Sep 2017
    Location
    New Bern, NC
    Posts
    4

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Thanks, will try to find one. On the counter rotators you built, did you have any special machine work done to the crankshaft? I was also thinking about changing over to roller tappets understanding there may be some power advantage by reducing engine power wasted on the flat tappets. Or would you recommend sticking with the flat tappets? Regards, Larry

  4. #4
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    Sep 2008
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    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    nothing special to the RH crank....did have the last pair balanced....

    on the same pair, we used roller rockers with the standard flat tappet camshafts....roller lifters will help reduce the friction but don't come cheap.....I can't say if they would be cost effective or not....if you plan to really use the boat (300+ hours a year) then your payback opportunity comes quicker....

    which ever you pick, I would suggest maintaining the 'peanut port' heads (they came be tapered to the gaskets but don't open them up to true oval port size) and maintaining a standard production cam envelope; don't exceed max lift/duration of the factory (GM) cams....

  5. #5
    Join Date
    Aug 2008
    Location
    Fairport, NY
    Posts
    1,670

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Add the starter too! I had felpro special rear main seal for RH engine but can't tell you what the diff was.

  6. #6
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    Sep 2008
    Location
    Maryland - USA
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    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    i finally got access to my shop manuals.....turns out they use 'helical grooves' where I used 'nubs' to describe the rear seal....and that style can be found on the front or rear seal. They also have service seals that are smooth and can be used in either RH or LH applications.....

  7. #7
    Join Date
    Sep 2017
    Location
    New Bern, NC
    Posts
    4

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Yes, found a service manual; shows the rear seal has like little veins that must form like a pressure head towards the seal lip, makes sense to have them opposite for opposite rotation, sorta like props, eh?

  8. #8
    Join Date
    Nov 2012
    Location
    South of Boston
    Posts
    73

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Quote Originally Posted by makomark View Post
    nothing special to the RH crank....did have the last pair balanced....

    on the same pair, we used roller rockers with the standard flat tappet camshafts....roller lifters will help reduce the friction but don't come cheap.....I can't say if they would be cost effective or not....if you plan to really use the boat (300+ hours a year) then your payback opportunity comes quicker....

    which ever you pick, I would suggest maintaining the 'peanut port' heads (they came be tapered to the gaskets but don't open them up to true oval port size) and maintaining a standard production cam envelope; don't exceed max lift/duration of the factory (GM) cams....

    I haven't been on the site for a while but just want to mention that 3 years ago I had my 1986 454s rebuilt with "mild" marine cams from "Comp Cams". Attention was paid to prevent exhaust reversion. Result was 380hp on the dino. 3 seasons and 120hrs and engines run great with a 10% increase in cruise speed.

  9. #9
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    9,811

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Just to reiterate on a few points:

    Yes, piston wrist pin offset will be opposite for the REV RH Rotation engine. Baring no conflict with valve reliefs and quench deck orientation, the FWD indexing notch now faces AFT.
    If there is a conflict, then you would order special REV RH Rotation pistons that would be manufactured with the opposite wrist pin offset.

    The TDC marking on the harmonic balancer will be followed by the 5, 10, 15, 20, 25, 30, 35 degree ignition advance markings in the opposite direction.

    Flat tappet camshaft profile must use flat tappet cam followers. (roller tip cam followers require the roller cam profile).

    Regarding front and rear seals..... the tiny oil wicking ribs/veins must be reversed for the REV RH engine. If not, you may see some oil leakage past the seal lips.

    Regarding the REV RH rotation engine camshaft drive system:

    ........ If chain and sprocket driven, the cam will rotate same as crankshaft. The drive and driven gears will keep the distributor and oil pump rotating in the std LH direction. This creates a downward force at the driven gear. A special RH rotation engine distributor may be required.

    ....... If twin gear driven, the cam will rotate in the Std LH Rotation engine direction, therefor nothing else needs to be changed.

    Regarding the oiling ports in the Std LH Rotation crankshaft:
    If you'll notice, these ports are indexed as to introduce oil to the load area just as the crankshaft is approaching TDC for that cylinder.
    In other words, the oil film is placed ahead of the upcoming bearing load area as to maximize lubrication during both compression and power stroke.
    Some of the
    reverse rotation cranks have the oil
    holes drilled symmetrically opposite.
    I would suggest that you further research this!




    NOTE: if by chance you have what we call "opposite of engine rotation capable" transmissions, you may be able to run two Std LH Rotation engines.




    .
    Last edited by RicardoMarine; 12-01-2017 at 07:17 AM.
    Rick ... aka Ricardo..... AQ series Volvo Penta repair
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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

  10. #10

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Hi all;

    Been doing some homework, and since you guys have forgotten more about engines than I will ever hope to know;

    1. with machining, etc. looks like a better deal for me to purchase two aftermarket new cores, e.g. Summit racing; I see they offer tall and short deck versions. Not sure what the original engines are, and what you would recommend.
    2. looks like stroker build would be cost effective way to get some more torque ? 489 or 496?
    3. If go for roller cams and lifters, saw some mention of fitment problems with exhaust and valve covers need to be bigger/custom, etc.?
    4. Any reason to get a gen VI block, as some builders mentioned they thought the one piece rear main seal was better. (I dunno, my vintage '86 mark iv's have been leak free to date)

    I'm sure as I dig myself deeper into this mechanical hole I will have more questions, but any help and recommendations appreciated, and thanks for the help so far!

    Cheers,
    Larry

  11. #11

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Oh yeah; and what static and dynamic compression ratio should I be trying for to continue to be able to use marina available pump gas?

    Larry

  12. #12
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    7,172

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Quote Originally Posted by ljfusco View Post
    Hi all;

    Been doing some homework, and since you guys have forgotten more about engines than I will ever hope to know;

    1. with machining, etc. looks like a better deal for me to purchase two aftermarket new cores, e.g. Summit racing; I see they offer tall and short deck versions. Not sure what the original engines are, and what you would recommend.
    2. looks like stroker build would be cost effective way to get some more torque ? 489 or 496?
    3. If go for roller cams and lifters, saw some mention of fitment problems with exhaust and valve covers need to be bigger/custom, etc.?
    4. Any reason to get a gen VI block, as some builders mentioned they thought the one piece rear main seal was better. (I dunno, my vintage '86 mark iv's have been leak free to date)

    I'm sure as I dig myself deeper into this mechanical hole I will have more questions, but any help and recommendations appreciated, and thanks for the help so far!

    Cheers,
    Larry

    without know what condition your current stuff is in, I can't comment on new blocks - most everything I've seen is short (or standard) deck height.

    stroking a BBC isn't cheap. Agree that displacement will help increase your torque....it may be more economical to 'buy' what you want vs build it.

    going with roller valve trains may introduce problems - depends upon what you start with. on the Mark IV's, machine work may be required to add the roller lifters - depends on the style. adding roller rockers causes different covers to be needed (or extensive mods of the stock tin). again, depending on the solution, there may e interference with the exhaust iron.

    going with a gen Vi block gets the roller cam but you (normally) need to go to an electric fuel pump.

    As far as CR goes, with out a knock sensor and a computer to monitor it, I think 9:1 is close to max....depending upon how you do the build you may get a little more....a lot depends on what 'normal' is, at the pump, in your area.....

  13. #13
    Join Date
    Sep 2017
    Location
    New Bern, NC
    Posts
    4

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Thanks Makomark;

    I think average octane is 89 where I normally fuel up; Regarding that CR, should I be using dynamic or static. (Until recently, I didn't even know there WAS a dynamic)
    The service manual I have shows the specs on 350's having 9.3:1, but the 454 (my engines) at 8.12:1. I was shocked at how low that was, but it is what it is....

    Long term plan is when the old iron needs it, I will have ready replacements, and I don't mind tying some money and time up to get there. Although I like the idea of rollers, it sounds like I will be going with flats. I don't know if there are any different exhaust manifolds available for folks swapping out mark iv's, as I am trying to see if anyone has "up graded" to a stroker and what there experience, good or bad, was.

    I know the originals are very good candidates for rebuild, and at the time of the removal, I will probably offer them up for sale, recouping some money. I am not expecting to come out ahead, since there is some law of physics or the cosmos that says boats have to COST money....LOL

  14. #14
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    7,172

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    more CR = more Torque but also means the engine is more senistive to detonation....so that's all trade space.

    When we rebuilt the MarkIVs, I think the resulting CR was ~8.5:1...ethanol was just introduced and we didn't want any harm from that....We added roller rockers but couldn't afford the roller cams/lifters. What works good is "mid height" rocker covers but they are a major hassle to find....the standard ones are too short and tall rocker covers rub on the exhaust ..... going to a Gen VI block eliminates all of these issues but introduces others.

    BOAT = break out another thousand....

  15. #15

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Thanks for the tip/info. I looked at a picture of the new 6l crusaders and my eye went to the exhaust manifolds. They look like they wrap the valve covers like a deli sandwich wrap. I'll consider myself lucky to have enough wiggle room on my old iron.

    Larry

  16. #16
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    Sep 2008
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    Maryland - USA
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    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    The big issue with the roller rockers, under the stock tin, is the oil baffle. Their height is a bit short as well. Those 'mid-height' covers, when they can be found, are the best solution as there's no 'riggin' them needed to get them to work and they provide plenty of clearance for the exhaust....at least with the 'beveled' ones (vs the square ones)....

  17. #17

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Quote Originally Posted by hottoddie View Post
    I haven't been on the site for a while but just want to mention that 3 years ago I had my 1986 454s rebuilt with "mild" marine cams from "Comp Cams". Attention was paid to prevent exhaust reversion. Result was 380hp on the dino. 3 seasons and 120hrs and engines run great with a 10% increase in cruise speed.
    Good to hear that, I'm just in the process of same, also bought a pair of Comp Cams torquer cams. Getting harder to find the reverse cam blank. What is your cruise speed, and do you notice any change in ability to get on plane?

  18. #18
    Join Date
    Nov 2012
    Location
    South of Boston
    Posts
    73

    Default Re: Rebuilding Mark IV's 454 cid with one counter rotating

    Quote Originally Posted by srfdude View Post
    Good to hear that, I'm just in the process of same, also bought a pair of Comp Cams torquer cams. Getting harder to find the reverse cam blank. What is your cruise speed, and do you notice any change in ability to get on plane?
    Of course cruise speed and getting on plane will vary widely depending on the boat. My boat is a 1986 Sea Ray 39ft Express with a 14ft beam. Very big boat for gas engines. Prior to redoing the engines the cruise was 17-18kts @ 3100 rpms. Props were 19X18 stock. Boat now cruises at 19-20kts @3100rpms with 20X18 props. BTW the props are all 3 blade. I have found 4 blade props over rated until you get to larger diesel boats. Fuel burn remained the same at .6-.7 mpg. Sorry but these engines burn fuel but so be it. BTW make sure you use oil with zinc additive to protect the flat tappet camshaft.

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