Ruddertwin Jugs

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    chris-p
    Canada Member - 1 Year
    Replies: 2473
    Topics: 157
    #6561

    I have not done a rebuilt on a Ruddertwin powerhead before.

    Should the jugs be very tight sliding over the pistons? Almost to the point of needing a mallet to move them along? I also find it very difficult to rotate the jugs around to line up the bolt holes as well, they are very tight.

    I have had these jugs nickel plated, and am wondering if that has something to do with it.

    mercuryman
    mercuryman
    US Member - 1 Year
    Replies: 353
    Topics: 127
    #54512

    yes

    Tubs
    Tubs
    US Member - 1 Year
    Replies: 2406
    Topics: 147
    #54513

    New Rings? Did you check the "all" the ring gaps in
    the cylinders before you put them on the piston’s?

    --

    fisherman6
    fisherman6
    US Member - 2 Years
    Replies: 1774
    Topics: 39
    #54523

    Also, did you measure the bore with a bore gage after the plating to see if the thickness of the nickel put the bore out of spec?
    -Ben

    OldJohnnyRude on YouTube

    Avatar
    hotrod

    Replies: 119
    Topics: 7
    #54545

    It sounds to me that you need to remove the cylinders to see what is wrong. Did you remove all rings and physically decarbon their grooves? Was each ring placed over its pin, facing the right direction, where it belongs ? Check all rings separately, when placed square in their cylinder, to see if the end gap is correct, which is .003-.010" for 3HP models and .006-.009" for 4HP models . The oiled cylinders should slide on fairly easily by hand after all the rings on the oiled piston enter the cylinder. A ruddertwin cast iron piston should have .0025 to .004" clearance in the cylinder. Cast iron pistons are made with less clearance than aluminum pistons. I think the plating is too thick.

    RICHARD A. WHITE
    RICHARD A. WHITE
    US Member - 2 Years
    Replies: 1645
    Topics: 130
    #54549

    If, as I recall, the inside of the cylinders got plated, that is your problem, too close of a fit, and that won’t fly. You will have to remove that plating somehow before continuing. Well unless you make your piston OD smaller by the amount of plating added to the bores, then you might have to trim the ends of the rings so the proper clearance is set for the piston ring end gap..

    http://www.richardsoutboardtools.com

    Avatar
    chris-p
    Canada Member - 1 Year
    Replies: 2473
    Topics: 157
    #54556

    Plating went on too thick at the bottom of the jug, end of the stroke. My hones don’t seem to have an effect on it at all. Ill have to get them professionally machined now I suppose. Thanks for the help all.

    Lesson learned. I tested the bore at the top of the jug only, Did not properly test the bore at the bottom of the jug, and was rushing so did not test for out of round, which it obviously is by about 7 thou.

    Actually if I were to restore another Ruddertwin, I would take the time to make a proper blank for the open end of the jug, to ensure no plating got into the cylinder. I ASSumed it would be easier to hone than it is, so I just dunked the whole thing.

    Avatar
    chris-p
    Canada Member - 1 Year
    Replies: 2473
    Topics: 157
    #54557

    Both jugs are very close in measurements.

    Top of jug (bottom of stroke) is about 2.4960 to 2.4970
    Bottom of jug (top of stroke) is about 2.4995 to 2.5045

    Piston measures about 2.4995 to 2.5010

    Avatar
    chris-p
    Canada Member - 1 Year
    Replies: 2473
    Topics: 157
    #54561

    Im assuming this piston is 2.5000"? (I am only using a digital vernier, my 2-3" outside micrometer is at work.

    So, I believe I should have the machinist bore out the cylinders to 2.5025, which would be at the bottom end of the cylinder to bore gap posted by Hotrod. That would still leave an out of round. Perhaps I go to the upper limit of the range and bore out to 2.5040.

    Ill have to check my ring end gap, see how much they are worn, and decide from there. Boring out too much may leave my end gap too high.

    Are NOS rings hard to come by for these? I personally have not seen them.

    RICHARD A. WHITE
    RICHARD A. WHITE
    US Member - 2 Years
    Replies: 1645
    Topics: 130
    #54586

    Boring them out will be interesting as I would suspect the plating will want to flake off instead of machining out nice and pretty like…
    The other concern is honing the bores out as the same may occur.
    As I suggested previously having them stripped of all plating then re-plating, just the outside this time, might be the best option.
    I would be highly concerned about that plating flaking off while the piston is doing its thing….

    http://www.richardsoutboardtools.com

    Avatar
    wbeaton
    Canada Member - 1 Year
    Replies: 668
    Topics: 74
    #54587

    I think you have a set of "display only" jugs. You will have to find a very good and very patient machinist who can bore a blind bore to less than .010". I agree with Richard that I’m afraid the plating may flake off after machining. Removing the nickel would be best. Or slap it together as a display motor and hang it on a stand.

    Wayne
    Upper Canada Chapter

    uccaomci.com

    Tom
    Tom
    US Member - 1 Year
    Replies: 380
    Topics: 39
    #54602

    Consider going back to the place that plated them and see whether they can "reverse plate" the inside of the jugs. You will need to block off the exhaust ports and plug the spark plug holes. They can use one of various solutions and plate it back on to a piece of copper. I don’t know how much damage could be done to the cast iron, though. You would have to discuss that with the plater.

    T

    Avatar
    chris-p
    Canada Member - 1 Year
    Replies: 2473
    Topics: 157
    #54619

    Ah shoot.

    Im by no means a cheap guy, but the plating was not cheap!

    I have another one to do after this. I may just paint those jugs lol

    Avatar
    pm-t2
    Canada Member - 2 Years
    Replies: 390
    Topics: 7
    #54654

    Try to avoid using the revere method to remove plating from any cast iron.

    The chemicals and the process itself are not kind to that sort of ferrous iron, and the results can be severe pitting after the strip operation is complete.

    The guys who used to do plating for me in Oakville always advised me to glass bead cast iron if it had any old plating left sticking to it for that very reason. The chemicals and the process will also attack the substrate. This is particularly true if there are any rust stains or deposits on the substrate as well. FWIW I followed their instructions on glass beading cast iron prior to nickel plating, I had a few Caille Liberty Twin flywheels done, and they all came out really nice because of the prep work I was told to do ahead of time.

    Hope this helps. Another FWIW – I ran into the same problem as you with nickel deposit on cylinder walls when I had a set of Lockwood Chief cylinders renickeled. it was only for the first inch or so of bore at the base of the cylinder, I did not have plate deposits further up the bore at all, at least none that I could detect either through fit & function testing nor measuring with a telescopic gauge.. I removed it just by hand sanding with fine paper. Nickel is relatively soft compared to chrome.

    Hope this helps.

    Best,
    PM T2

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    brook-n

    Replies: 188
    Topics: 6
    #54697

    I share the same opinion as Chris on this, I have experienced this myself first hand.
    Unfortunately in some cases it might just be easier to start over with another pair
    of good used jugs.

    Respectfully

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