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Results 1 to 16 of 16
  1. #1
    Join Date
    Jun 2010
    Location
    Ocean City NJ
    Posts
    55

    Default reverse rotation gear drive for cam

    Does anyone have instructions on setting up a reverse rotation camshaft? Are the gears set to a mark like a standard timing chain. I need to check my reverse rotation engine to see why I get only 3k rpms under load and low idle vacuum (15 in). The vacuum gauge label states late timing, but I had verified TDC and initial timing is at 8 degrees and total advance is 26 degrees. Can the low vacuum be from the valve timing off and letting compression leak out? If the gears were mis aligned, would the engine run? This engine spins over easy like low compression, but it starts easily. The other engine in the boat revs well past 4k and idle has 20in of vacuum.

  2. #2
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    7,153

    Default Re: reverse rotation gear drive for cam

    Lots of potential issues that need to be addressed here.

    First... you do not mention which engine this is.
    Not all reverse rotation engines use a camshaft gear drive.
    Many older ones, yes!

    Today, most are chain driven, and the cam rotates with the crankshaft direction.
    It's all part of the camshaft profile.

    The procedure to check phasing, should be similar to that of a std LH Rotation engine.

    To check #1 TDC accurately, the PPS (positive piston stop) procedure is used.
    You can check and eliminate an issue with a balancer that may have slipped and is no longer aligned for #1 TDC.

    I'd start there, and move forward from that point.
    A balancer that is not accurate, will throw off your ignition timing.
    Bad ignition timing may be part of what's giving you the low vacuum reading at idle.

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

  3. #3
    Join Date
    Jun 2010
    Location
    Ocean City NJ
    Posts
    55

    Default Re: reverse rotation gear drive for cam

    I have been troubleshooting this engine for a while now. Its generic marinized gm 350 engine. It replaced my crusaders that 1 had seiezed and other very tired (2800hrs) on the boat. Bought boat with known bad engines. Took me a year but got the boat in the water early July. Run the motors got about 15hrs on them. WHere the issue is the RH engine (reverse) won't power past 3k under load. I got a pistonstop from summit and timing tapes. Check balancer and applied timing tape (6 3/4 dia) The balancer was correct, it had 4 factory marks, vertical, BDC TDC and 90 degree mark from vertical. Set timing to 8 degree advance, rev motor verify 26 total advance. Run boat no better, swap carb (1409) no difference, pull carb reset floats and larger inlet valves, and 1 step up on secondary jet. Run boat verify secondaries are flowing fuel, still not going over 3k. Port motor powers past 3k and is now slowed by the starboard but was able to hit 4k.

    Had local mobil mechanic stop down at boat, he thought wrong camshaft, verified firing order, and kinda made me believe its a cam issue and would take alot of time to correct.
    Vacuum readings at idle were lower then the other motor, and maybe this motor was assembled "wrong" well I pulled the timing cover and the marks were on the money. Oh well the gaskets are under 20 bucks.
    http://i765.photobucket.com/albums/xx295/sammywell2009/IMG_2347.jpg
    are the reverse rotation cams the same as standard? Since the distributor, oil pump are run off the cam and the cam turns clockwise in both types. Could I have the wrong type? Just hate to tear apart this motor. tho I have basically done that all ready
    http://i765.photobucket.com/albums/x...9/IMG_2332.jpg

    The second picture shows the boat at 2400 rpm this is 21kts with GPS, so the boat is not slow. I have hit 30kts at 3000rpm so the boat has potential.


    I got word today from a prop shop, and its possible I got mis matched props. He stated that if the prop was more then 3 on the pitch off, I would see this difference in rpms. I bought the boat with unknown props, going to have to pull them just to be sure.

    I would gladly pay for someone to look at the boat, as I think I'm missing something obvious. Ocean City NJ

  4. #4
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
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    7,153

    Default Re: reverse rotation gear drive for cam

    Quote Originally Posted by paw2000 View Post
    ............ well I pulled the timing cover and the marks were on the money. Oh well the gaskets are under 20 bucks.

    are the reverse rotation cams the same as standard? Since the distributor, oil pump are run off the cam and the cam turns clockwise in both types. Could I have the wrong type? Just hate to tear apart this motor. tho I have basically done that all ready

    I got word today from a prop shop, and its possible I got mis matched props. He stated that if the prop was more then 3 on the pitch off, I would see this difference in rpms. I bought the boat with unknown props, going to have to pull them just to be sure.
    OK..... you do have a gear driven camshaft.
    And yes.... the oil pump and distributor will both rotate CW.... whether gear driven cam, or chain driven cam....... doesn't matter, since we don't change the oil pump rotation.... therefor we don't change the distributor rotation.
    (the distributor's driven gear changes for a chain driven cam in a reverse rotation engine)

    The cam gear set sure looks like it is indexed correctly if it's the correct gear set for a Reverse Rotation engine.
    (I'm not even sure if that makes a difference... TDC is TDC... and that's where the markings always align.)

    As for the cam profile (other than one being reversed from the other), the #1 cylinder Intake and Exhaust valves should open/close very close to that of the Port engine.... just in reverse crankshaft rotation.
    If the homework had been done by the engine supplier...., the cam profile should match the Port engine.

    To check the profile duration/lift, etc, (against the Port engine), all you'd have to do would be to use a degree wheel on each engine, and place a dial indicator on #1 Int/Exh and compare the two profile readings.


    You mentioned that this Stbd engine turns over easily. Do you mean "easily" as in a bit too easily????
    Was this new Reverse Rotation engine equipped with cylinder heads, are did you install your own?

    If you installed the cylinder heads, is it possible that you have a different piston/cylinder head combination between the two engines.
    Example:
    Full Dished pistons being used with 76cc chambers.
    This combination would not produce the same C/R, nor power, as one with 64cc chambers.

    Conversely, a Flat Top piston being used with 64cc chambers would render a too high C/R in a 5.7L SBC......... one that is not suitable for marine cruiser use.
    If this engine did not Detonate, it may produce more power than the other... but this is not a good combination for marine cruiser use.

    Rambling questons here... but it may lead to something:
    1. Are the transmissions both the same ratio?
    2. Can you varify that the props are both pitched the same? Perhaps pull both props and take them both in for comparison.
    3. Is each engine's progressive ignition advance the same, ending with a TA at the same RPM?
    4. Can you swap carburetors without too much trouble?
    5. Good fuel pump pressure?
    6. Good quality ignition spark?
    7. Equal cylinder pressures between the two engines?
    Last edited by RicardoMarine; 08-20-2011 at 12:57 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  5. #5
    Join Date
    Jun 2010
    Location
    Ocean City NJ
    Posts
    55

    Default Re: reverse rotation gear drive for cam

    Good Questions, I'll answer as best as possible
    1, Both trans are 1.52-1 as marked on tag B/W velvet drives
    2. All I know about the props that they are marked Chris Craft equi-poise and had a 3 digit number like 736 stamped( don't remember exact number) on them. Will be pulling off, here's the rub, marina I'm at wants to charge to haul out and block and then to put back in. Almost $700 to do this. I asked about how much there shop rate is and if the boat can be lifted for 5 min and then walked to the slip with out props. They looked at me like I asked are you kidding?? I'm going in at low tide (3ft or less under the boat) to pull them, I have the puller and socket ready to go.
    3. The distrubuters are same, I took the values off the good motor and set that to the starboard, no improvement.
    4 Already swapped carbs. Tho I did see improvement on the port motor after cleaning and float adjust.
    5. Haven't tested pressure, tho I can, my vacuum gauge came with the tee fittings. I can run 10 minutes at 3k and motor doesn't stumble.
    6. Was thinking of swapping distributors and coils, possible distributors is not playing nice and limiting me to 3k rpm (might explain the exact rpm limit)
    7, Did not do compression test. When I say cranks easy, the starter spins them well. I was hoping the cam was indexed wrong and the valve timing was off, this would explain the ease of crank and low performance. I don't think I have low compression due to cylinder failure, I might back off rockers just to see, they came adjusted and motors have no knocks or noises.

    Motors came assembled, they are 4 bolt main blocks, new GM not rebuilt, had oil pan off when I got them, and noticed the factory markings on the mains and crank showing bunch of numbers.

    I'll reassemble the engine and test fuel pressure

  6. #6
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    7,153

    Default Re: reverse rotation gear drive for cam

    Re; # 3 and # 6.

    3. The distrubuters are same, I took the values off the good motor and set that to the starboard, no improvement.

    6. Was thinking of swapping distributors and coils, possible distributors is not playing nice and limiting me to 3k rpm (might explain the exact rpm limit)
    3..... when you checked this, were you checking/setting BASE only, or were you looking at TA numbers, and at the same RPM on each engine?

    6...... Yes.... I agree! However, I see no need to do this if you will look at your dynamic advance in degrees up to the limit RPM......... Then compare the two.
    If the Stbd engine is NOT receiving the correct progressive advance, it will not produce the power expected.

    As for #7 adjusting rockers....... note that what we're actually doing is setting the cam follower plunger depth within the cam follower body (aka "lifter").
    Find ZERO lash, and follow the recommended OEM setting..... (I.E., the % of adjustment past ZERO)
    This places the plunger where is needs to be, while making sure that each valve is capable of fully closing.

    I don't want to suggest how you set these.... but for example:
    There is approximately .100" of plunger travel.
    1/2 turn past ZERO sets the plunger less deep than 1 full turn would.
    (has to do with rocker arm ratio, and stud thread pitch)
    I would favor a lessor plunger depth over that of a deeper plunger depth for reasons that would be for another story/another day!


    I think that you should do a Comp Test, and compare the readings between the two engines.

    Good luck! Keep plugging away..... you'll find it!
    Last edited by RicardoMarine; 08-20-2011 at 08:12 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  7. #7
    Join Date
    Jun 2010
    Location
    Ocean City NJ
    Posts
    55

    Default Re: reverse rotation gear drive for cam UPDATE

    Well today I have some news. After doing a compression test and getting reasonable numbers cylinder 2-160 4-165 6-165 8-165 1,3,5,7-160 ( this was done dry) I pulled the intake and found the gaskets oily. There was oil film in the heat crossover passage. So it looks like I had an internal leak. I replaced the gaskets and got higher vacuum from 14inches up to 16-17 inches. The motor sounded bad, I was checking things and found if I covered the starboard side primary throttle, the rpms would smooth out and vacuum increased. Well I pulled the carb again and cleaned the primary circuit and the motor has 21inches of vacuum. I reset timing and idle, also idle mixtures and it runs well. Tomorrow I'll test it for power, its looking good. The engine has 2 filter per motor, so I was surprised that the carb again had "crud" in it. The boat did weather hurricane Irene so its possible stuff got stirred up.

    This is a first for me to see intake gaskets fail, they actually sucked up oil into them. I didn't see any smoke but then I wasn't looking for any. The giveaway is low vacuum. Other then carb gaskets and an intake plug, there is nothing else to leak other then the gaskets. If the motor was high mileage, thats different. This also effected timing as the low vacuum would increase as dizzy was rotated, so it would fool me into thinking timing was off.

    Thanks for the help

  8. #8

    Default Re: reverse rotation gear drive for cam

    I have a question about your RR engine. I have the same engine but I can't get it to fire up. I have used the firing order from my manual but they don' t work, what firing order are you using on that engine.

  9. #9
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,561

    Default Re: reverse rotation gear drive for cam

    The firing order in the factory manual is the valid. If a marine (GM) manifold, most have std and rev timing orders as part of the casting. You need to verify TDC and initial timing as well as mechanization for the proper firing order (note the gear driven cam reverse roation engines typically use a 'standard' rotation distributor). If the ignition is correctly setup, you should be able to get it started if in decent mechanical shape. From there you only have fuel left to deal with.

  10. #10

    Default Re: reverse rotation gear drive for cam

    It a fresh rebuilt, the problem l'm having is the dizzy is turning cw. When l reverse the starter it turn ccw but the oil pump was then pumping back into the pan. Compare the direction of the gear that turns the dizzy with the old block and it match up if that mean anything. Could it be my dizzy, l had it rebuilt. Any advise would be greatly appreciated. It was along block when l got the engine l just put all the hardware on.

  11. #11
    Join Date
    Sep 2008
    Location
    Maryland - USA
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    Default Re: reverse rotation gear drive for cam

    "the problem l'm having is the dizzy is turning cw"

    If you check the manual, both LH & RH engine distributors rotate CW, for the 'newer' engines. Turns out there is more than one way to put together a "reverse rotation" engine and the method used drives the selection of several other components. The 'normal' (default GM method starting before 1980) for a marine build was to use a gear drive. This results in an overall economic benefit due to minimizing the parts count. Though the camshaft is different (from the STD - LH - rotation), the distributors and oil pumps are common.

    So, if it was rebuilt using the 'factory' approach, the distributor should rotate CW...#1 wire goes in the "standard position" (though it isn't critical) and the wires are installed on their tower legs (or in their sockets), going CW, but in the 'reverse order'....1-2-7-5-6-3-4-8.

    Based on the description of the oil pump's operation, the distributor should rotate CW and you need to get the wires in the proper order (see above) as well as get the starter wired up the way it was. The rebuilder/distributer/reseller that sold you the long block should be able to verify the camshaft and camshaft drive mechanism used...removing the rocker covers and watching the valve actions when rotating the crankshaft will also give you positive indications of what hardware was used.

  12. #12
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
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    Default Re: reverse rotation gear drive for cam

    Mark, I see a potential for some confusion here.

    The OP (paw2000) apparently has 350 cu in GM engines, and Angler4reel has 5.8 Fords as per his own thread in the Mercruiser section.
    The 5.8L Ford distributor rotation is CCW.... the SBC GM is CW.

    Angler4reel.... as mentioned in your thread, your 5.8L ignition distributors will rotate CCW.... not CW.
    Has to do with the oil pump and the advancing flyweights within the distributor.

    Either your RH Reverse Rotation engine has the wrong starter motor on it, or the wrong camshaft installed.
    There's got to be a simple explanation as to why you aren't getting this engine to fire up.

    I don't mean to tell you how/what to do here, but I believe that staying with your original 5.8L Ford topic thread would better serve you.


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

  13. #13

    Default Re: reverse rotation gear drive for cam

    Thank for the advise Rick, I'm new to the forum, didn't know were to go, I'm just desperate for a solutions, I saw the feed on RR, so l figure l would pick someone brain.

  14. #14
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    Mar 2009
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    Portland, Oregon,
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    Default Re: reverse rotation gear drive for cam

    Understand that you are somewhat desperate for a solution....... I'd be also.

    However, when we remain in one thread, everyone reading it will be able to see the evolution of the thread, and will be better able to offer you help.

    I'm going to peek in at your original thread in a few minutes.
    Hang in there...... we'll figure this out.

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

  15. #15
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    Sep 2008
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    Default Re: reverse rotation gear drive for cam

    Quote Originally Posted by Angler4reel View Post
    I have a question about your RR engine. I have the same engine but I can't get it to fire up. I have used the firing order from my manual but they don' t work, what firing order are you using on that engine.
    Same engine to me = generic GM 350 small block which is what my thoughts covered...if you found the subject at hand is an old 351 ford, and found it in another forum.....well, you're a better detective than I.

  16. #16
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    Default Re: reverse rotation gear drive for cam

    Quote Originally Posted by makomark View Post
    Same engine to me = generic GM 350 small block which is what my thoughts covered...if you found the subject at hand is an old 351 ford, and found it in another forum.....well, you're a better detective than I.
    Mark, no detective work was required.
    I was attempting to point out that in this thread, the OP (paw2000) apparently has 350 cu in GM engines!
    In Angler4reel's original thread > Need help with 1976 351 Windsor < he suggests that he has the 351 Windsor engines. One Std LH rotation, and one Rev RH rotation. I believe that his comment re; "having the same engine" is simply an error.

    Angler4reel is having an issue with engine and distributor rotation.
    His 5.8L Ford distributor rotation will be CCW.... the SBC GM will be CW.



    As we can see, it's always best to stick with the original thread, and/or not Hy-Jack an existing thread.

    Angle4reel, if you are reading this, how 'bout an update to your original thread?
    Did any of my questions, comments or images help you?
    Any progress?


    .
    Last edited by RicardoMarine; 11-15-2011 at 07:27 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

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