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  1. #1

    Default LH and RH engines

    Will someone advise me how to tell the difference of a LH and RH engine and how they work? I have 1978 crusader 270 engines. The port engine if standing in front of the engine crankshaft turns counter clockwise and the distributor looking down on it turns clockwise. Starboard engine crankshaft turns clockwise and the distributor looking down on it also turns clockwise.

    The firing order are opposite on both engines.

  2. #2

    Default Re: LH and RH engines

    IIRC you tell rotation from the back of the engine looking towards the front. Left engine goes CCW and the right goes CW. Distribitors only go CW. I don't have as deep of knowledge of the inner workings as some but I believe the rotation is dictated by the timing gears or chain at the front of the engine. I'm sure one of the guru's will chip in a while.

  3. #3
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    Default Re: LH and RH engines

    Ayuh,..... Duke is dead on Right,....
    Any Grease is Better,... Than No grease at All....

  4. #4

    Default Re: LH and RH engines

    What is considered the front of the engine?is it the crank case where the belts are or is it where the engine joins the transmission? Secondary do all distributors rotate CW on a two engine setup? These are counter rotating engines not transmissions

  5. #5
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    Default Re: LH and RH engines

    Quote Originally Posted by jaybirdboat View Post
    What is considered the front of the engine?is it the crank case where the belts are or is it where the engine joins the transmission? Secondary do all distributors rotate CW on a two engine setup? These are counter rotating engines not transmissions
    To be precise, GM has made every combination possible, which is 4 combinations of rotations. But, I've only seen 2 used by marinizers. In both cases, the CAMSHAFT and therefore the DISTRIBUTOR turn the same direction. (the cam turns the distrib. and oil pump) Only the CRANKSHAFT and the STARTER MOTOR and the belt accessories go CW or CCW. Most coolant pumps and alternators are "bi". Raw water pump also, but hoses reverse on those. There are some not so obvious piston and rod install differences and sometimes rear oil seal differences, but likely not on the single piece oil seal. That's all I think I know.

  6. #6
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    Default Re: LH and RH engines

    Every Marine (factory) manual I've seen uses the flywheel rotation (looking from the flywheel towards the distributor) as the reference setup; LH = CCW rotation of the flywheel and RH = CW.....V-drive installations can induce 'non-intuitive' installations as can some velvet drives with certain reductions....

  7. #7

    Default Re: LH and RH engines

    Quote Originally Posted by makomark View Post
    Every Marine (factory) manual I've seen uses the flywheel rotation (looking from the flywheel towards the distributor) as the reference setup; LH = CCW rotation of the flywheel and RH = CW.....V-drive installations can induce 'non-intuitive' installations as can some velvet drives with certain reductions....
    Makomark
    The port engine distributor goes clockwise looking down on it looking from the front of the engine the flywheel goes counterclockwise the starboard distributor also goes clockwise looking down on and that same engine turns clockwise looking from the front.

    The Marine mechanics are telling me on these crusader engines that the distributor should go the same direction as the engine that's why I am confused but my engines are working perfectly with the firing order reversed from port to stRboard.

    As stated earlier I am not a mechanic but I also don't want to get ripped off so I like to learn

  8. #8

    Default Re: LH and RH engines

    Makomark
    what do you mean by nonintuitive installations of velvet drives and also with certain reductions ?

  9. #9
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    Default Re: LH and RH engines

    my two cents - time to find new mechanics.....

    in post #7, not sure what your are describing or asking.....especially with "the distributor should go the same direction as the engine " comment. maybe asking again will help....as would putting one observation in its own sentence.

    Regarding post #8, normally, for inline gear installations, the props spin outwards at the top - RH on Starboard & LH on Port. Also, the Port engine is LH'd and the Starboard engine is RH'd. Gear rotation is same for input and output. on the 1.88:1 and 1.91:1 velvet drives, the engine rotations are opposite - due to the gear rotations being opposite (input to output). the V-drive arrangement adds another layer of complexity (for reference points) because the engines are installed 'backwards' (flywheel forward)....

    For completeness, the 'newer' production engines are all LH'd and use 'newer' gears that can handle full power with the gear selector in either position. so 'new' boats have two LH'd engines with the same gears (shift cables installed to provide desired shaft rotation) and the 'normal' RH prop being to starboard.

  10. #10

    Default Re: LH and RH engines

    OK let me try again. These are 1978 crusader 270's. I'm asking should the distributors go the same direction as the fly wheel? My port engine distributor goes clockwise looking straight down on the distributor. if you look from the front of the engine that same port engine flywheel moves counterclockwise. Starboard engine distributor also turns clockwise but the fly wheel turns clockwise
    if that's the case mine do not but the engine is running perfectly and I don't understand why .

  11. #11
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    Default Re: LH and RH engines

    .........................
    Quote Originally Posted by jaybirdboat View Post
    OK let me try again. These are 1978 crusader 270's. I'm asking should the distributors go the same direction as the fly wheel?

    I'm not quite following your question!
    There is a 90* angle change between the horizontal axis of the crankshaft/camshaft and the vertical axis of the distributor shaft.




    My port engine distributor goes clockwise looking straight down on the distributor.
    That is correct!

    if you look from the front of the engine that same port engine flywheel moves counterclockwise. Starboard engine distributor also turns clockwise but the fly wheel turns clockwise
    Tell us more about your installations! Are these V-Drives????
    Typically, a standard shaft drive Port Engine is Std LH rotation and the Stbd Engine will be the REV RH rotation engine.


    if that's the case mine do not but the engine is running perfectly and I don't understand why .

    Some of this will be redundant..... so bare with me:

    As noted, engine rotation is always determined as though viewing the flywheel end.
    LH Rotation is standard for cars, trucks, industrial, marine, etc.
    When viewing the flywheel end, this crankshaft will rotate in the CCW direction.

    RH Reverse Rotation is the opposite.
    When viewing the flywheel end, this crankshaft will rotate in the CW direction.

    *******************
    The front of an Engine will typically be the end with the crankshaft balancer, Circulating Pump, the timing chain or gears, and will be the Non-PTO end (PTO = power take off).
    The rear of an Engine will typically be the PTO end. (the end with the flywheel on the crankshaft)
    This rule applies regardless of the installation. I.E., standard installation w/ flywheel facing AFT, or flywheel facing forward such as w/ a V-Drive installation.
    Front is Front........ Rear is Rear!

    *********************
    #1 cylinder will always be the Forward-Most cylinder. It may be on the Port side or on the Stbd side depending on which engine.

    **********************
    OK...... LH and RH rotation engine Ignition Distributor direction.
    For the REV RH Rotation Engine, we DO NOT change the direction of the Engine oil pump. I have never seen or heard of an oil pump that operates in the opposite direction.
    Therefor we continue rotating the distributor in the Standard direction in order to achieve engine oil pressure.

    For the REV RH Engine, this is accomplished via several methods:


    ............ when we drive the camshaft via Chain and Sprocket, the camshaft rotates same as the crankshaft.
    In order to continue driving the oil pump correctly, the Helical gear cut on the camshaft "drive" gear and the distributor's "driven" gear are cut in an opposite fashion.
    The distributor thinks that it's in a standard LH Engine.

    ............ when we drive the camshaft via twin gears, the camshaft is now rotated in a Std LH Engine direction, so the Helical gear cuts remains standard.
    Once again, the distributor thinks that it's in a standard LH Engine.

    ............ when we drive the camshaft via a four gear set-up (crank, cam and two idler gears), the Helical gear cut on the camshaft "drive" gear and the distributor "driven" gear are again cut opposite.
    Once again, the distributor thinks that it's in a standard LH Engine.

    So..... no matter how the camshaft is driven, the SBC distributor will always rotate CW, as will the oil pump!

    If you know of a mechanic who suggests otherwise, he is simply mistaken.

    ***************************************

    Pistons:
    Most of our SBC
    cruiser engine piston wrist pins are offset for the crankshaft direction.
    For the REV RH rotation engine, the wrist pin offset must now be turned around.


    *************************************

    SBC REV RH rotation firing order:
    Since we use #1 cylinder @ TDC C/S for camshaft phasing, etc, the #1 cylinder still leads in the firing order.
    We begin with #1, but we now reverse the order beginning with what would have been last just prior to coming full circle.
    In other words..... what was originally
    1-8-4-3-6-5-7-2 ........ is now 1-2-7-5-6-3-4-8.




    .
    Last edited by RicardoMarine; 07-22-2017 at 10:12 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.

  12. #12

    Default Re: LH and RH engines

    I never realized we had such smart people on this forum. I really appreciate your responses to both of you. I will tell the mechanic and wanted to charge me $3000 to take out and put in a new camshaft and distributor to go get a real job as my engines are working beautifully. I just never understood why as I was told by my marine mechanic that the distributor had to turn the same way as the flywheel which now I know that's not the case

  13. #13
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    Default Re: LH and RH engines

    Quote Originally Posted by makomark View Post
    Every Marine (factory) manual I've seen uses the flywheel rotation (looking from the flywheel towards the distributor) as the reference setup; LH = CCW rotation of the flywheel and RH = CW.....V-drive installations can induce 'non-intuitive' installations as can some velvet drives with certain reductions....
    Just to add some clarity:

    Even while the V-drive engine sits in the hull with the flywheel facing FWD, the flywheel end is still considered to be the REAR of the engine.
    Likewise, even while the V-drive engine sits in the hull with harmonic balancer end facing AFT, this end is still considered to be the FRONT of the engine.




    .
    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.

  14. #14
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    Default Re: LH and RH engines

    Quote Originally Posted by jaybirdboat View Post
    I never realized we had such smart people on this forum. I really appreciate your responses to both of you.
    1..... I will tell the mechanic and wanted to charge me $3000 to take out and put in a new camshaft and distributor to go get a real job as my engines are working beautifully.

    2..... I just never understood why as I was told by my marine mechanic that the distributor had to turn the same way as the flywheel which now I know that's not the case
    1..... ask him to show you where (in a shop work or service manual) it states this!
    Then ask him to show you the camshaft that he would be installing in place of the camshaft that is not working correctly!
    Then ask him to explain why your engine even runs!!!!!!!

    2..... ask him to show you a SBC Marine Engine oil pump that operates in the opposite direction.


    Do this politely and respectfully in hopes that he will learn something from YOU!

    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.

  15. #15
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    Default Re: LH and RH engines

    OK.... one more thing regarding Mark's post #9.

    It was mentioned that most twin engine scenarios today incorporate Std LH Rotation engines.
    I get that..... because it is less expensive to produce all Std LH Rotation Engines.

    With twin engine boats, the prop direction change is accomplished with the transmission direction.
    I can't quite explain why the term is not commonly used today, but in my world these have always been referred to as "Opposite of Engine Rotation" transmissions.

    Not all transmissions are capable of this.
    For those that are, it makes engine use and replacement a breeze.





    .
    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.

  16. #16
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    Default Re: LH and RH engines

    There are the velvet drives that have the output rotation opposite input rotation but they aren't full power capable in reverse....the newer ones (VD 5000 series, and the ZF/Hurth variations are full power reverse.....they typically do NOT have the F & R position indications at the control valve connection.

    Regarding GM productions engines (older stuff), you will ALWAYS see the gear drives, for the cam, on the reverse rotation engines. I've never see it documented anywhere but the only logical reason is $$$ - only one distributor to stock and support.

    And on the V-drives, like Rick said, the engine's 'handed-ness' is ALWAYS determined in the industry standard manner - looking at the flywheel (towards the block)....due to the various V-drives, there isn't a 'normal' rotation engine installation position.

    Finally, based on your descriptions, if you have inline gears, they are 1.88 or 1.91 to 1.....

  17. #17
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    Default Re: LH and RH engines

    One more thing if I may.

    When we use the Chain Driven camshaft for a REV RH Rotation
    Engine, the opposite direction helical gear cuts cause a change from an "up-load" gear separation force to a "down-load" gear separation force.

    The standard SBC ignition distributor is designed to counter an up-lift force (the gear face against the housing).
    The true SBC REV RH ignition distributor is designed to counter the down-load force.

    Point being...... we do not simply change the driven gear to a REV RH driven gear and call it good!
    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.

  18. #18
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    Default Re: LH and RH engines

    ................
    Quote Originally Posted by makomark View Post
    Regarding GM productions engines (older stuff), you will ALWAYS see the gear drives, for the cam, on the reverse rotation engines. I've never see it documented anywhere but the only logical reason is $$$ - only one distributor to stock and support.
    Yes.... I fully agree....... twin gear driven camshafts were quite common back then.
    This keeps the camshaft rotating in the Std direction...... so no change to the ignition distributor is required.


    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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