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seattlejester

Undoing aluminum valve cover warpage

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Hey guys,

 

I've been searching the internet for quite a while and haven't been able to pin point a real answer.

 

I bought some aluminum valve covers for my 7m. They are essentially one offs.

 

They have a slight bow in the middle. How would I go about fixing that?

 

Online I have found people suggest hitting traditional valve covers with a hammer, but I think that applies to steel and this one is aluminum. Others have suggested putting it to a belt sander but this one has a valley on the flange that retains the rubber gasket. 

 

Is there a way to take a slight bend out of a large piece of aluminum? The seller assured me it isn't a problem, but I'm worried about leaking oil from the head or stripping a bolt trying to tighten it down. 

 

I was thinking of maybe ratchet strapping the center down to something more robust, but I'm not sure if that would take out the bend or if it would just bounce back. Some people have suggested adding heat into the equation, but others have said that it could mar up the aluminum if not distributed evenly.

 

Just figured I would take your guys thoughts on the matter.

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Those clamps look like they would be good for spreading some of the load. I'm concerned that if I tried too hard it might pull the threads out of the head. 

 

I'm not sure a thicker gasket is a possibility, but maybe some RTV or something might help if it starts leaking.

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 I'm concerned that if I tried too hard it might pull the threads out of the head. 

 

Make a fixture.  A flat piece of metal, some holes, a tap.  You'll either find that it pulls down easily or there's no freaking way.  Or just stick it on the head, torque the bolts lightly and see what happens.

 

I tried this technique on a cylinder head and was surprised at how easily the warpage pulled down.  Made me wonder about all of the effort spent making heads flat.  You're just trying to stop some oil from leaking out and air from leaking in.

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Sorry for the delay, I'm planning on heading to my car tomorrow and grab them and take pictures. I want to say it looked like maybe 1/4 or 3/8 of an inch in the middle with the two covers being held flange to flange. I think you guys are making a good point that it may be minor enough to compress especially given it's relative length and small width. 

 

The concern with lapping or flattening the surface with a sander is that it is a valley type of gasket so the flange has a groove for the gasket to sit in.

 

I would just install it, but I put the engine far back enough where the stock hood latch is actually preventing me from installing it as the breather holes were moved to the back by the creator. I have my nutserts on the way to install the brackets for my new latches, so I figured if there was a recommended way to relax or unwarp the head before they went on I could save myself some trouble.

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1/4" to 3/8"?!?!? That's beyond warping and I have no clue what to suggest, good luck with it though.

 

Note he said: I want to say it looked like maybe 1/4 or 3/8 of an inch in the middle with the two covers being held flange to flange.

 

Holding the valve covers flange to flange does not give a true picture of how much the cover is actually warped. He needs to place the covers on a flat surface and measure how much the flange deviates from the table.

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Note he said: I want to say it looked like maybe 1/4 or 3/8 of an inch in the middle with the two covers being held flange to flange.

 

Holding the valve covers flange to flange does not give a true picture of how much the cover is actually warped. He needs to place the covers on a flat surface and measure how much the flange deviates from the table.

Regardless of how you measure it, if the gap really is 1/4-3/8 then one or both covers are beyond help. I'd like to know how make that much of a warp without cracking something.

 

No amount of lapping or grinding or whatever is going to give you a servicable cover.

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Not quite as bad as I recall. 

 

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Maybe a 1/16 on the edges coming to about 1/8 in the middle

 

Once again the caveat is that this is a valley style gasket, the gasket itself has a bit of protrusion. I think it really will seal, I was just hoping for some kind of input into maybe relaxing it a bit. The story is that it was bolted to a jig when it was made and then a coilpack mount was welded in after the fact to connect them. I'm guessing it warped when that was done. 

 

I think I'll just go with newzed's solution. Maybe I can find a spare head to bolt it onto without the gasket to kind of gauge how far the center will go down. 

 

Bought on craigslist, and I quite like these, they don't really make this kind of stuff for my engine, so I would like to make it work.

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If I had these and wanted to keep them.... I would clamp them down to a thick piece of steel and heat them, then slowly add clamping pressure until they lay flat or flatter.  Let cool naturally while still clamped.  You may have to repeat this.  Just take it slow and keep the heat and pressure even, should work.

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