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Spray welding

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spigot
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2011/04/24 14:52:49 (permalink)
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Spray welding

Does anyone have any experience with this??

The impression I get is that it can be hit a miss and the guides will get screwed from the heat.

Porting head and I popped through behind the inlet valve guide, looks to be a casting fault.

Tossing up to try and repair or start again, head has good exhaust guides and hardened seats. I am going to group 1 valve sizes.
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    JamesR
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    RE: Spray welding 2011/04/25 19:28:43 (permalink)
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    quote:
    Originally posted by spigot

    Does anyone have any experience with this??

    The impression I get is that it can be hit a miss and the guides will get screwed from the heat.

    Porting head and I popped through behind the inlet valve guide, looks to be a casting fault.

    Tossing up to try and repair or start again, head has good exhaust guides and hardened seats. I am going to group 1 valve sizes.

    i think spray wending is only good for building up a surface, not sure if it would be any good for filling a gap/hole?
    #2
    PeterM
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    RE: Spray welding 2011/04/26 02:22:21 (permalink)
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    Spray welding is usually only for building up or replacing lost surfaces. Not for filling holes etc.

    What head is it?

    If the head can easily be replaced best to start again.

    It might hurt but best to replace the head. Considering costs and future engine reliability.

    If the head can't be replaced best to find a good engine shop who can refer you to a good repairer.
    #3

    spigot
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    RE: Spray welding 2011/04/26 10:42:02 (permalink)
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    I have seen it used to fill smaller holes before but it requires experience.

    Its an EB head that WAS in really good condition. I was finishing of the inlet bowls behind the guide and it fell through. I wasn't mucking around with the port job but there should have been material there. I have ported about a dozen heads before and this has never happened before, and its a mate's head too.
    #4
    Timw
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    RE: Spray welding 2011/05/05 21:07:53 (permalink)
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    Commonly called Plasma spraying and is usually used to reclaim surfaces on expensive parts in the aircraft and space industry.

    But is being used in the commercial industrial field to reclaim a lot of surfaces that was not possible even several years ago. It is not a cheap process and although you could have many hours of work in the head I would be surprised that the cost could justify the repair with the experience required of the repairer.

    I believe is has been done on cast iron before, but in the area that you specify may not be possible to actually carry it out.

    I would talk to somebody who has good record of tig welded cast iron to see if the repair is possible that way, but a failure could result in a hydraulic lock which will be even more expensive and spectacular.

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    Timw
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    RE: Spray welding 2011/06/05 14:07:18 (permalink)
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    quote:
    Originally posted by spigot



    I have seen it used to fill smaller holes before but it requires experience.

    Its an EB head that WAS in really good condition. I was finishing of the inlet bowls behind the guide and it fell through. I wasn't mucking around with the port job but there should have been material there. I have ported about a dozen heads before and this has never happened before, and its a mate's head too.


    I have seen and used ultrasound NDT methods work on head porting to ensure material available to carry out and to check for cracks, this save the problem that you encountered as due to the casting tolerances not all heads are the same thickness in the same area, you probably saved your mate a tow truck fee or a DNF on the race track with an expensive bill to boot. Without the right equipment and experience it can be a very hit and miss affair.

    I also learned this the hard way. I have even seen a crack appear from the exhaust port to the water galley on a test head that was being used to test some different cams. With less than 2 Hours running. This head had been hot and cold tested and pressure tested without fault before being used. Ported yes, enough material yes, could have been an air pocket in the vicinity of the valve but the cooling water added to the radiator was the same as was drained before
    the head was removed to change cams. Your guess ????

    The NDT method also ensures integrity of the head when used, but sometimes cannot be used in all area due to the probe unable to reach the required area for test.

    #6

    spigot
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    RE: Spray welding 2011/07/05 10:07:05 (permalink)
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    I have confirmed that the cost of spray welding is not viable. Also when you spray weld the heating proceedure destroys the bronze guides which would make the head worthless to repair.
    #7
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