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Thread: annealing copper head gaskets

  1. #11
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    Thx Bosch. I am confident again.
    Tom, my engine shop (head shop) boss and I were looking at the gaskets, observing a dark portion between 2 adjacent bolts, and considered whether the cylinders might need planing. He suggested a minute "dusting" to both the head and the cylinder to be sure they were both planar. I agreed, and now both surfaces are smooth, without the concentric (to the bore) ridge-rings we usually see in the cylinder's head gasket surface. I do have linear scuffs, the result of the planer.
    The engine is a post-war Chief with aluminum heads. ..... where were you headed with that? .... I'm all ears, btw.

  2. #12
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    Filibuster!

    With aluminum heads, you do not want copper headgaskets anyway. They make horrible impressions into the aluminum, whether by dielectric corrosion, or the "beating" of compression of the harder copper into the softer head casting.
    Please get composites from your favorite supplier.

    The warpage is common, usually right over the intake port where the casting is thinnest (attached: Note plate glass for inspection; usually just a few swipes on a large stone displays it, but it takes many more to level it).

    ...Cotten
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    Last edited by T. Cotten; 04-07-2015 at 09:22 PM.
    AMCA #776
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  3. #13
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    Quote Originally Posted by T. Cotten View Post
    With aluminum heads, you do not want copper headgaskets anyway. They make horrible impressions into the aluminum, whether by dielectric corrosion, or the "beating" of compression of the harder copper into the softer head casting.
    Er, um, that would mean just about every post-WWII BSA and Triumph imported to the U.S. is in serious trouble, because most used Cu head gaskets and Al heads. But, can you explain why a piece of flat, soft copper pressed against the harder Al head would make any impression at all, as well as why it is worse to press soft Cu against the Al than the harder iron of the cylinder? Any defects in the Al head certainly will be transferred to the soft Cu, but since the Cu is flat (and soft), not vice versa. As for electrolytic corrosion, I've had a fair number of engines apart over the years and have yet to see any evidence of it.

  4. #14
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    I dont know anything about Brit machines, BoschZEV,

    But I pulled H-Ds and Indians out of barns that have been scarred. It is one reason why so many have been milled.

    And if its green, I call it corrosion, no matter what the chemistry.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  5. #15
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    Quote Originally Posted by T. Cotten View Post
    But I pulled H-Ds and Indians out of barns that have been scarred.
    And if its green, I call it corrosion, no matter what the chemistry.
    Green is copper sulfate and it only develops when copper is exposed to air and moisture in an acidic environment. Because of this, if you found green corrosion on copper head gaskets it means the heads were not bolted to the cylinders. So, my advice to filibuster is if he plans to leave his engine disassembled in a leaky chicken coop for 75 years he should place the copper head gaskets in a separate box. Otherwise his engine will be fine, there won't be any corrosion, nor will there be any impressions made in the Al by the flat, soft Cu head gaskets.

  6. #16
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    Quote Originally Posted by T. Cotten View Post
    (attached: Note plate glass for inspection; usually just a few swipes on a large stone displays it, but it takes many more to level it).
    Cotton, I hadn't noticed this comment until just now. On the principle that metal can never be put back once it's removed (which isn't always the case...), instead of grinding a warped head flat I would tap a couple of holes in a thick plate and remove as much of the warpage as possible by the use of shims at ~90-deg. to the warp.

    For example, if when on a flat plate I could slip a, say, 0.010" feeler gage between the head and the plate, I'd start out by bolting the head down with 0.015" shims at the two 90-deg. locations with respect to the gaps. After I released tension from the bolts I'd measure again to see how much of the warp was gone. Based on what I found I would repeat with different shims.

    Not all warping is due to a simple twist so where those shims have to be placed depends on the location of the gap(s). But, only when I had "de-warped" it as much as I could in this way would I consider grinding way the last 0.001" or so.

  7. #17
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    BoschZEV!

    That's the cast iron cylinder (sometimes called a cylinderhead, of course, because it holds the valves) in my photo, not a head on top.
    I have partially straightened aluminum auto heads as you describe, with an oven.

    I cannot explain the mechanism of the "warpage" over the intake port on Chiefs, but it is quite common on aluminum H-D OHVs to warp over both ports.

    ....Cotten
    PS: Copper sulphate is blue. Verdigris be green.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  8. #18
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    Quote Originally Posted by T. Cotten View Post
    BoschZEV!

    That's the cast iron cylinder (sometimes called a cylinderhead, of course, because it holds the valves) in my photo, not a head on top.
    I have partially straightened aluminum auto heads as you describe, with an oven.

    I cannot explain the mechanism of the "warpage" over the intake port on Chiefs, but it is quite common on aluminum H-D OHVs to warp over both ports.


    ....Cotten
    PS: Copper sulphate is blue. Verdigris be green.
    I'll report in tonight on where the black areas were on my head gaskets, but I think they were over the intake port, or near it.
    And I'll order a pair of composite gaskets just in case I have some kind of issue with the copper. Got a couple of days before I land the cylinders on it.

  9. #19
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    Quote Originally Posted by T. Cotten View Post
    PS: Copper sulphate is blue. Verdigris be green.
    Not quite right. Copper Sulfide is blue, but Copper Sulfate is green. Although other compounds form as well depending on the local environment (oxides, chlorides, carbonates...), it's the sulfate from the acidic sulfur pollution in the air that is given the primary "credit" for turning copper roofs green.
    Last edited by BoschZEV; 04-08-2015 at 02:01 PM.

  10. #20
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    Quote Originally Posted by fillibuster View Post
    And I'll order a pair of composite gaskets just in case I have some kind of issue with the copper.
    It's a shame some incorrect information has made you nervous about copper, although composite gaskets will be fine as well. However, many such composite gaskets are sandwiches with copper as the top and bottom so there's a good chance you'll still end up with copper. Which, for the reasons I've given, is perfectly fine other than for very long term storage in leaky chicken coops...

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