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  1. #1
    Join Date
    Sep 2017
    Location
    New Bern, NC
    Posts
    3

    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
    Posts
    6,826

    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
    3

    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
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,826

    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
    1,632

    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
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    6,826

    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
    3

    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
    63

    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
    9,191

    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 08:17 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.

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