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Thread: How To Avoid Machining

  1. #31

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    Quote Originally Posted by vpt View Post
    Yes the shim washers. And to check them you had to bolt the cam down in place, pull cam out, change shims, bolt cam back in, repeat. Then the cam timing was whole nother event of good times.
    Actually not too bad with thoughtful planning. At each position you can check one valve on each side. Make notes. Rotate cams to position for dismounting. Remove cams, check each current shim and swap with required. Reassemble, recheck clearances and if you're REALLY LUCKY you're ready to button it up.

    Compare that to setting valves on a Maserati Biturbo. The cam carrier is bolted to the head with a gasket. The carrier must be removed to adjust shims. Since torquing the same gasket twice won't necessarily put everything in the same position, you pull out a new gasket, replace and torque, recheck and do that over again. (Do they sell gaskets by the dozen?) Oh, and the intakes on 18 valve engines are operated by one cam with the valve shims riding on the RIM of the follower bucket. And some people wonder why stereotypes develop about British/German/French/Italian engineering.
    .
    "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill

  2. #32
    Join Date
    Nov 2012
    Posts
    113

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    Two ideas that we use on the farm.

    1. Hagens Brew Equal parts acetone and ATF?
    Shake while applying. You will be surprised.

    2. Muffler cutting air tool with a semi blunt point
    Put on center of hex and give it a few good burps.
    olf20 / Bob

  3. #33

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    Fascinating thread!

  4. #34

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    Believing in Kroll and heat started think about how to apply heat to such a large Heat sink. For sure using a torch the head will draw heat away making very high temp required to do any good.

    The slow wood stove idea is a good one but not many have a slow wood stove handy. Friend of mine bends Shotgun stocks with two red lamps, kind fast food places use to keep French fries hot. Bathes the wood in linseed oil applies the heat 24 or more hours, he gets the wood up to about 200 Degrees. Method is pretty universal with stock fitters.

    I bet 200 degrees from heat lamps and lots of Kroll several days would get to the problem, and not risk the head. You can use force but it has its problems. Dealing with a water pump on a boats heat exchanger now. 4 bolts one snapped off with heavy force to get at the impeller to replace. Held together with 3 bolts and Permatex now. Had to use force boat out of commission without a working seawater pump. Not able to go slow. Slow always better if you have the time.

    No go then machine the bolts out.

    Boats

  5. #35

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    Heat will have tremendous effects on freeing up stuck parts, but mostly when it is applied as a "shock". In current situation the only practical way to do it, as I see, would be arc welding the head of the plug. That is pretty much a no return point though, so perhaps saved for the last. Just before final desperation and cheater bars that result in breaking loose or breaking off....in about 50/60 ratio
    But really, if nothing gives after a good long warm soak with penetrants, whacking at the plugs with punches and hammers and trying air impact tools, then I would resort straight to machining them out. This be probably the least of all the evils....

    If it is technically possible I would also try to apply the penetrant oils from the side of the cooling channel (literally fill the head up with it) and not just from the top side of the plug. It has a way better chance to seep inbetween the treads from the bottom side of the plug in the channel.
    Last edited by markx; 03-13-2019 at 06:09 PM.

  6. #36
    Join Date
    Dec 2009
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    Stevens Point, WI
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    7,841

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    Quote Originally Posted by TGTool View Post
    Actually not too bad with thoughtful planning. At each position you can check one valve on each side. Make notes. Rotate cams to position for dismounting. Remove cams, check each current shim and swap with required. Reassemble, recheck clearances and if you're REALLY LUCKY you're ready to button it up.

    Compare that to setting valves on a Maserati Biturbo. The cam carrier is bolted to the head with a gasket. The carrier must be removed to adjust shims. Since torquing the same gasket twice won't necessarily put everything in the same position, you pull out a new gasket, replace and torque, recheck and do that over again. (Do they sell gaskets by the dozen?) Oh, and the intakes on 18 valve engines are operated by one cam with the valve shims riding on the RIM of the follower bucket. And some people wonder why stereotypes develop about British/German/French/Italian engineering.


    Thats why I drive a honda.
    Andy

  7. #37
    Join Date
    May 2006
    Posts
    14,534

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    Iv worked on the Mazerati V6 Bi-turbo and also got called in to do "crash forensics" on one,

    If you think the Bi-turbo has some engineering flaws you should check out it's bigger brother the V-8 Quattroporte, just as much "engineering fun" and then they top it off with an interior floor panel piece that relaxes and warps and as the holding screw starts to vibrate out the panel is cleverly engineered to act as a one way "sprag" so that it will allow the gas pedal to go bye and then stop it from coming back,
    the results are close to wide open throttle with the type of carburetion that has a venturi for every cylinder coupled to no rev limiter, every valve floats and gets stuffed into every piston - fun time...

  8. #38
    Join Date
    Oct 2012
    Location
    San Antonio TX, USA
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    2,467

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    Probably won't help here but I've had some success with alternating heat/ cold cycles. Map torch for a while, then freeze spray (or can of compressed air held upside down), then heat, then cold for 4 or 5 cycles. Bolt or nut usually unscrews without drama.

  9. #39
    Join Date
    Dec 2016
    Location
    Helsinki, Finland, Europe
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    3,077

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    Quote Originally Posted by boats View Post
    Believing in Kroll and heat started think about how to apply heat to such a large Heat sink. For sure using a torch the head will draw heat away making very high temp required to do any good.

    The slow wood stove idea is a good one but not many have a slow wood stove handy.

    Boats
    I'd bet almost everyone of us has a gas bbq on the yard.

    But I'm more of the shock-heat class of school, OP mentioned MAPP gas but its not comparable to oxy-acet. (Oxy-MAPP should do it tho.)
    Arc welding is the next best thing after oxy-acet or even better. Make some rounds with TIG welder to those bolt heads until they are cherry red and partly melted from the middle and let them cool.
    Heat them enough fast and there shouldn't be much worry about melting the threads on aluminium.

  10. #40
    Join Date
    May 2006
    Posts
    14,534

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    Don't underestimate reverse to forward shots with the "get it gun"

    it sounds counterintuitive but it's really not - all's your looking for is initial movement and due to the elasticity of materials they at first really don't know the different between tightening and loosening, so - so many times they reach a limit in one direction and won't budge, using the opposite direction can be the ticket to get some kind of movement, then when you go back to the other direction things can get a "running start" it's worked for me so many times it's my go to trick with some penetrating oil and just letting the gun do the work... guns set at a predetermined level will out-due just trying to undo it with brute force every time...

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