Conference vicki::boats

re                       <<< Note 1147.0 by UNYEM::FRASCH >>>
>                         -< All Things are NOT Equal >-

	First the topic title...  I think you might mean 

		"Not all things are equal"  (-:


	Anyway, you describe a symptom that another noter had a while 
back - it turned out to be (can you b'leeve this ?) different pitched 
props.   So, before getting into cable adjustments I guess I'd check 
some of the more obvious things first - like are both engines in a 
comparable state of tune, etc.

	Reg

    Reg,
    
    
    I think the tune is pretty good. I put in new parts in August, and set
    the timing. They are electronic ignitions, so not much else to worry
    about (I think).
    
    
    I did take a couple of turns of adjustment at the Carburetor linkage
    which made some difference for the better, which is why I think it's
    mechanical.
    
    There are two 19"X21" props that are only 2 years old ---- seem to be
    OK.
    
    As I said, I'm new to the big V-8, twin screw arena, so treat me like
    totally stupid (shouldn't be too hard) and I'll soak up the info like a
    sponge!!!
    
    Thanks,
    Don

    
    let me agree with reg, and i'll explain why.
    
    first: if the throttles are "x" much out (more than seems ususal)
    
    it ain't the obvious, not the throttles.
    
    and if your engines are in tune, oh well, no here.
    
    i would definitley check your props, or for a loose shaft at the 
    
    coupler.
    
    i had the same problem, when i bought the boat the previous owner
    
    told me that new props had been put on the season before.
    
    up to this point all he said seemed to be true.
    
    my first season i went absolutley crazy trying to adjust the
    
    throttles at the helm without luck.  when i laid up,
    
    i told the marina to pull the props and send them out.
    
    about a week later ( i think it was H&H) called and gave me the
    
    bad new.  they should be 18x18, they were in dia. 16" and just over
    
    17"  no wonder one throttle had to be advanced ahead of the other.
    
    you can check these yourself without pulling them, but not be eyeball.
    
    i wound at their recommendation buying new ones.  the difference
    
    in throttle movement toady is miniscule, say a 1/4 to 3/8".
    
    
    JIm
    
    
    
    

    Well, It's on the cradle, so now is the time to check it out! I'll pull
    the props and send them out to the prop shop for a look-see!
    
    Thanks,
    Don

re                     <<< Note 1147.3 by MR3MI1::BORZUMATO >>>
>                           -< it aint the throttle >-

    
>    let me agree with reg, and i'll explain why.

	OK, I'll let Ya agree... (-:
    
>    first: if the throttles are "x" much out (more than seems ususal)
    
>    it ain't the obvious, not the throttles.

	I was thinking along the lines that OK, maybe cables 
wear/stretch, but not by very much.  On the other hand, if one engine 
takes a lot more throttle (actually "throttle lever angle" is all we 
know at this point) then its more likely that either the load on it is
different or it just doesn't respond the same 


	A different load could be caused by, amoung other things;

		prop size (diameter or pitch)
		trannie rati<fergettit>
		any difference in drag, e.g. shaft bearings, etc.

	Different response...  Well, I guess this is the symptom 
you're seeing, so its difficult to isolate )-:
	Twin screw boats aren't in my foreseable future, but I'd try 
to somehow check the state of tune, maybe you could try performance
testing the boat separately on each engine to figure this out ?  
Are there any differences of temperament in the two engines ?
e.g. is one a much better/worse cold starter than the other one ?
do they idle down equally smoothly ?  Do they rev as freely in neutral ?
etc.

 
	Reg

    ain't it fun,
    
    :>)  
    
    before you pull them take a measurement, look on the prop hub
    
    to determine what dia and pitch, it should be stamped there.
    
    if suspicious then pull.
    
    check both shafts, especially the one that needs more throttle.
    
    
    was nice of reg to let me agree>>>>>>>>>>>>>>>
    
    JIm

    
    Assuming thisboat has dual Tachometers..... are the engines
    running at different RPMs when this mismatch of throttle 
    controls occurs?
    
    Rick

    
    Rick,  whats happening from what i understand, is that the throttles
    
    need to be mismatched in order for the engines to be synchronized.
    
    If the throttles are matched one is running at a lower rpm..
    
    Which me thinks is a set of mismatched props.   Also if the throttles
    
    handles are set even, the boat will turn in one direction, in favor
    
    of the engine with higher rpm.
    
    my 2.369c
    
    JIm
    
    in one direction.   

    I would think that with the help of one other person it would be easy
    enough to determine if the carbs (you do have carbs, not fuel
    injection ?) were both at full open position at full throttle position
    on the levers.  If not, then there must be an adjustment at either the
    engine or where the two sets of cables (from the two helms) come
    together.  There is probably adjustment at both locations.  The reverse
    gears should be marked with their reduction ratios but I suppose
    somebody could have modified one.  If they are Warners (ie: hydraulic)
    you would probably have to open them up to determine this unless the
    engines could be run and you had a hand-held tach that could be used to
    measure output shaft RPMs.  (But don't do this dry with prop shafts
    connected or you'll fry all your strut bearings, packing, etc.)
    One last thing.  Do you have counter-rotating engines/props?  If no,
    then there is a possibility that one prop could be sucking air from the
    side of the boat and causing a cavitation situation.  Ideally, the
    right hand prop (when viewed from the stern) should rotate to starboard
    (or clockwise) while the lefthand prop should rotate to port
    (counterclockwise).  If both props rotate in the same direction, I
    would expect the engine that doesn't meet the above to need less
    throttle because the prop is getting less of a "bite" on the water.
    
    Wayne (who will probably never be in a position to worry about multiple
    engines in the near future.  15' boat, 1 engine, 1 steering wheel, 1
    throttle, 1 shift lever, no payments)
    

    
    By the way, what make and model yr is the mutha...
    
    sounds like a luhrs or silverton....  the chryslers have a ring
    
    to it..
    
    
    JIm

    If one engine is sick, and producing less power, it will need
    a 'bigger' throttle setting to achieve the same RPM under the
    same load, as the other.

    Same thing for load.  If one prop were of a higher pitch,
    that engine would need a 'bigger' throttle setting to
    maintain the same RPM.

    If it were my problem, I would (with the engines off) have
    someone advance the throttle until the throttle-plate in one
    engine is fully open.  Then do the same with the other.  If
    the throttle controls are in very different positions -- it's
    the cable/linkage.  If the throttle controls are in a similar
    position, the problem is either power produced, or load
    presented.

    Are there any 'accessories' being powered off one engine?
    (alternator, generator, pump, etc.)

    My .02:
    
    Do U have an enginer synchronizer?  This would be a pointer to the
    engines being in Sync and validate Tach readings.
    
    ALternately, if the boat pounds and sounds for Sh#% when throttles are
    equal, it says the engines are out of sync -- Ergo the throttle
    mismatch.
    
    Tis all load dependent --  You could have a sick engine (the one with the
    most throttle)-- Do a compression check -- Wet and Dry -- If not that,
    could be a problem with the fuel delivery system. 
    
    The shaft coupler (Flange that attaches to the back of the tranny)
    could have the locking bolts backing out of the shaft (There are 4
    Flange coupling bolts coupling the shaft flange to the tranny.  There
    are two bolts 180 degrees diplaced going into the shaft.)
    
    You could have something wrong with your strut bearings on the high
    throttle engine side.
    
    The props are mis-matched -- The higher throttle engine has a bigger
    pitched prop.   The prop hub has a number stamped on it -- First # is
    diameter, second number is Pitch (1918 = 19 inch diameter, 18 pitch"
    
    Welcome!
    
    Dennis
    
    Welcome to the world of "Double-Trouble."

    Boy, you guys are honing right in on what I have! Some details:
    It's a 1978 Silverton "Sport Cruiser", 34' long, 12'9" wide with twin
    Chrysler 360 Cube V-8s. They have 600 Hrs on them. There are no
    differences in loads (generators, etc.) between the engines, they have
    4 bbl carbs and electronic ignition.
    
    One observation from your comments ---- the stuffing box packing on the
    fast engine leaks too much and needs to be repacked (which might mean
    it has less drag on the shaft than the other "slow" engine?). 
    
    I have a "Quest" electronic synchronizer on it which shows equal engine
    speeds at different throttle positions. And, I can really hear them
    come "in synch". At WOT, the starboard engine is about 150 RPM slower
    than the port one. The throttle positions are then full open, and
    against the mechanical stops.
    
    At idle, the throttles are both even, and at the lower stops, and the
    engine RPMs are equal. (about 600 RPM) The tachs and synchronizer
    agree, and they sound right.
    
    The difference in throttle positions gets increasingly worse going from
    full idle to WOT (until I hit the stops).
    
    I checked the carbs visually, and they both seem like they are full
    open at full throttle --- but that's just an "eyeball".
    
    The more I think about your comments, the more I suspect that once I
    repack one stuffing box, the problem will basically go away!!!
    
    
    Regards,
    Don

    
    
    i don't think so....   unless the other is so tight
    
    to cause that much drag...
    
    
    i still think its something els... but i'm not here to say i'm
    
    right, you got a lot of good info here.
    
    good idea to check it out.
    
    JIm

    Don,  I also doubt that it is your stuffing box causing that much of a
    difference but I might be concerned that the tighter one may be scoring
    your prop shaft if too tight.  I had to replace my shaft because the
    prior owner ran it too tight.
    
    Were both engines installed at the same time?  If not, perhaps one carb
    is jetted differently than the other.  WOT position would seem the same
    but one engine would be getting less fuel and run slower.  Idle/slow
    speed would not be effected by this due to the seperate idle circuit.
    It wouldn't be a big deal to pull the jets and check there sizing. 
    Also, check for any signs of bent carb linkage past the throttle stop.
    Even though it's hitting the mechanical stop it still may not be
    opening the carb all the way.  You need to observe the butterflies
    inside the carb venturies to be sure they are wide open.  One last
    thing.  I will assume that the secondaries open via mechanical linkage
    and not vacuum but if they are vacuum, make sure that there are no
    leaks in the vacuum line leading to the carb which would prevent it
    from being fully opened at WOT.
    Wayne

    
    to see if it is a carb  problem, why not swap the carbs between
    engines. If teh problem follows the carbs- find out what's wrong. IF it
    doesn't start running compression checks, check timing , valve lift
    etc. Could be someone changed one of the engines at one time and it has
    a different cam in it, or different compression ratio , or different
    valve diameters.
    
     I had a freind who bought a used boat with a 350 chevie- it wouyld run
    lousy at hogh speed. She finally ble a head gasket and we discovered
    two different heads- the vlave diameters were different, and from
    examining the heads, IT appeared hat the volumes were different. We 
    ended up with matched heads complements of the local JY and the engine
    ran beautiful.
    
     There's lots of shade tree mechanics out there- seems to be more so on
    boats for some reason.
    
     Dick
    

    
    WOw -- Now into the FERMI zone -- How about at WOT for one engine U
    have valves starting to float -- Would that have a difference in WOT?
    
    --ALSO -- What does your trim look like -- If one side is deeper in the
    water, it will run slower than the one on the high side.
    
    It could be the tranny.
    
    It isn't the stuffing box.
    
    Dennis

    I just thought of something -- 600 hours -- 15 year old boat --  
    
    34 footer?
    
    Hmmmm -- That says an average of 40 hours running per year -- That
    ain't much -- If these are original engines, I'd be wondering about the
    accuracy of the hour meter -- Of course the boat could have been used
    by a little old lady who only drove on Sunday - and never over 20 MPH!
    
    The plot thickens!
    
    Dennis 

    
    I guess i would make a list of all the good suggestions made here.
    
    divide them into 2 parts.
    
    in storage             in water
    
    
    check all the things on land you can, then launch and check the others
    
    in the water.  obviously some things can't be checked on land.
    
    check/do one thing at a time to avoid confusion, ( isolate the fault)
    
    and go from there.
    
    the hours don't seem to have much affect here, the owner says
    
    they run pretty good.  
    
    previous owners on unduly scruples, sometimes tend to spread it
    on kinda thick.
    
    like my new props, sure thing dude.
    
    JIm

    If I check ALL the things you guys suggested, I'll never get in the
    water next year! (just kidding) After thinking about it, I couldn't see
     how a 360 cube engine could be pulled down by a stuffing box either!
    It should have some torque.
    
    I suspect it is engine related somewhere. I know the previous owner
    very well (original owner), but he had a guy trying to buy it for 5
    years --- ran out of money two years ago and lost the boat. It looks
    like one engine (the fast one) had a valve job, but the other one
    didn't !!!!!! AHAH!
    
    Don

    Take a look at the bottem of the controls.  On some the cable can be
    connected to to a different hole or screw on the level arm.  This will
    change the throttle angles.
    
    A couple of quick checks.  1.  Are the levers lined up at idle? 
    2.  Are the levers lined up at WOT?
    3.  Are both flybridge and lower station controls acting the same?
    
    A two person check would be to open the throttles until the secondarys
    just start to open.  Then check the throttle lever positions.  If the
    carb secondaries open at different positions then you will get the
    large mismatch.
    
    Try the simple low cost ones first after checking that the props are
    the same and the trannies are the same. 
    
	Kc
    

    A valve job on one engine?  I think you may know the solution to your
    problem already.  I wouldn't doubt that you would see a 150 RPM
    difference between one engine with the valve job and the other engine
    that doesn't (and now has 600 hours on it).
    Wayne
    

    
    I agree, one stronger than the other....   if this wasn't an issue
    
    i'd stick with props.   but props are losing out here.
    
    JIm

    Even a compression test done at 1000 - 1500 RPM's may not show any
    difference the non-valve job engine has weak springs.

I think I'll step back a bit, make notes of all the suggestions, and go forward as
much as I can out of the water.

I had forgotten about a comment from the original owner that the other guy had a
valve job done on one engine --- "he thought"! It's hard to believe there could be
that much difference in two engines, but then I've never dealt with twin screws
before.

I'll do all the mechanical checks, including compression, on the cradle, and then do
a tune up including a vacuum test, timing, and carb adjust when I launch in April.

However, my gut still tells me it's mechanical! I've asked a couple of other guys at
the marina who have twin engines and the answer I get is " oh yeah, mine does it too,
I just live with it --- ".

Anyway, I have a lot of good ideas from all of you to go play with. After all, isn't
that why we buy these things in the first place??

T-H-A-N-K-S !!!!!

Don