Top End Installation - Valve Timing vs Ignition Timing 1100/1150

Discussion in 'GS Boxers' started by geometrician, Jun 13, 2018.

  1. geometrician

    geometrician let's keep going...

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    Greetings Oilheads!

    I've just finished installing a new updated left top cam chain tensioner and tensioner blade (end broken off, almost all pieces recovered from sump) for a friend. Pulling the subframe & airbox and routing the hoses, cables & electrical during reinstall was (almost!) a bigger job than removing the gearbox/final drive and clutch/flywheel to drift the tensioner blades' pivot shaft out. The pivot shaft e-clips and washers were not as tricky as I first thought; it was a matter of taking my time to study the situation and arrive at the right process and the tools and tricks I'd need to do it without dropping anything into the engine cases. Now that I've come up with an actual procedure (YouTube videos are more proof of concept than instructional) I'm ready to do this for anyone in need!

    The owner decided to go with new ring sets (115,000 miles, no serious oil consumption or odor when running) as the top ends had to come off to provide access to the pivot shaft- who wants to split cases when it can be avoided? The factory cylinder crosshatching is clearly visible and two of the pushrods had ends that were loose enough to rotate when inspected- not bad at all.

    I am installing the top ends but not installing the cam sprockets/chains until I'm sure that my left cylinder "0T" mark is at ignition TDC and not overlap TDC. I still have the front timing (engine) cover on (I didn't order a replacement gasket, my mistake I reckon) and am hoping to get it right the first time without being able to see the ignition marks on the front timing sprockets. 15289043942031684236614.jpg

    Is there another way to confirm ignition vs cam timing while still having the front engine cover in place?
    #1
  2. GS Addict

    GS Addict Pepperfool

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    If you zip tied the chains to the cam sprockets you should be good to go.
    #2
  3. geometrician

    geometrician let's keep going...

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    Alas the cylinder heads, pistons and cylinders were removed before I received the project- and that fellow is currently riding in the Himalayas
    #3
  4. GS Addict

    GS Addict Pepperfool

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    Then just lock the crank at TDC and the sprocket arrows should be level horizontally.
    Hand turn the engine gently CW viewed from the front to confirm clearance.
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  5. Steve W.

    Steve W. Boxer Pilot

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    To the OP; I guess it's a little late, but are you aware of the "steptoe" method of replacing the guide rails? Just cut a notch and slip it over the pin.

    There is only one "tdc" position for the crank, as both sides are out together and the firing pulse is the same due to the wasted spark configuration. The cams are 360* of crankshaft rotation apart.

    Cheers
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  6. SplitLanesLikeMOSES

    SplitLanesLikeMOSES ....................

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    The front cover doesn't have a gasket. It's RTV. I use Threebond 1211.
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  7. geometrician

    geometrician let's keep going...

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    Not too late; there are always other projects however she's taking up prime real estate on the lift at the moment, and I wasn't going to proceed until I was sure one way or the other

    I wasn't aware of this method of replacing the tensioner blade(s). I'm not sure the owner would opt for this; he's a pilot and doctorate of mechanical engineering lol. The material is pretty brittle (new or old blade) and would be curious how much one would have to remove of course we always envision the worst case scenario and as this is a Trans-Continental ride I'd sure hate to think what might happen and where! Could you provide a link?

    You hit the nail on the head with the spark answer- I figured BMW would have no wasted spark at overlap, and was afraid I'd have the plugs firing when the intake charge wasn't compressed and ready

    Cheers to this forum once again, the best on the planet IMHO :beer
    #7
  8. geometrician

    geometrician let's keep going...

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    I must admit I'm not used to engines without base gaskets - using liquid sealants instead.

    Now I'm looking for the product to use. I have Yamabond, Threebond which I typically use for assembling engine cases and super-pesky leaking side & valve covers. I also have some of the modern Permatex UltraBlack silicone RTV which is pretty amazing stuff with seemingly endless applications

    I have fresh Hylomar (most recent sliced from Cincinnati VALCO, great price) which I an a strong believer in- but I've never used it as a "pressure" sealant, and I view base gaskets as such from the compression of the cylinder assembly from the studs as well as the pull created by the combustion cycle.

    So what's the wisdom of the forum? :confused
    I'd say I'm afraid the hylomar won't last another 120,000 miles, and the Yama/Three-bonds seem too thick and "goopy" for the (assumed) precision required for the base gasket... 1st World Problem, too many choices!!!
    #8
  9. GS Addict

    GS Addict Pepperfool

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    I use this exclusively. Never had a leak.

    [​IMG]
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