How to repair (straighten) header flange? - LotusTalk - The Lotus Cars Community
 
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post #1 of 8 (permalink) Old 12-29-2008, 10:55 PM Thread Starter
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How to repair (straighten) header flange?

If a header's flange is not completely flat. (the flat piece that goes against the motor) What's the best way to even out the surface? Have a machine shop grind it flat?

also, the cat was damaged in shipping and I've already had a muffler shop make the outlet round again. It was a bad dent that flattened out a portion of the edge. Hopefully I won't have installation issues with that.


thanks!

** save ~10 lbs gain 1 hp ** EQ: Y=(190*X) / (1984-X) where Y is (HP) and X is (lbs)

'07 Lotus Exige S310


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post #3 of 8 (permalink) Old 12-30-2008, 11:19 AM
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If the header is not used, have the machine shop true up the flange using a press and then take a thin skim off the flange surface using a surface grinder if needed. If the header flange is warped from use, it may be better to have the flange ground flat because the header flange warped as a result of stress relief and it will likely try to warp again the next time it is heated if it is just pressed back to being flat.

Last edited by tesprit; 12-30-2008 at 11:24 AM.
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post #4 of 8 (permalink) Old 12-30-2008, 11:40 AM
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Ara,

Here's some advice relating to your issue from DMH...for what it's worth....

"No flange is perfectly flat after welding -- none. If you know how to install them, it just doesn't matter. And if you have to ask how, you shouldn't be undertaking the work."

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post #5 of 8 (permalink) Old 12-30-2008, 11:53 AM
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Quote:
Originally Posted by Jack View Post
Ara,

Here's some advice relating to your issue from DMH...for what it's worth....

"No flange is perfectly flat after welding -- none. If you know how to install them, it just doesn't matter. And if you have to ask how, you shouldn't be undertaking the work."
I was just being smug. Torque the flange bolts when hot/warm and it will be just fine.

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post #6 of 8 (permalink) Old 12-30-2008, 05:41 PM
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No flange is perfectly flat after welding, that is why you then grind it flat on a surface plate.

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post #7 of 8 (permalink) Old 12-31-2008, 08:31 PM Thread Starter
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Thanks all for your advice!

Quote:
Originally Posted by Jack View Post
Ara,

Here's some advice relating to your issue from DMH...for what it's worth....

"No flange is perfectly flat after welding -- none. If you know how to install them, it just doesn't matter. And if you have to ask how, you shouldn't be undertaking the work."
I have never worked on cars before the Lotus. I've tried to do all the work on this car myself. Save when I don't have time and I get impatient with all the goodies lying around. So I don't know all the tricks just yet.

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I was just being smug. Torque the flange bolts when hot/warm and it will be just fine.
Yeah, that's what I'm gonna do. By advice, I will re-torque the flange bolts after 500 miles. Maybe at 250 miles and 500...

** save ~10 lbs gain 1 hp ** EQ: Y=(190*X) / (1984-X) where Y is (HP) and X is (lbs)

'07 Lotus Exige S310


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post #8 of 8 (permalink) Old 07-07-2017, 05:13 PM
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Quote:
Originally Posted by shay2nak View Post
If a header's flange is not completely flat. (the flat piece that goes against the motor) What's the best way to even out the surface? Have a machine shop grind it flat?

also, the cat was damaged in shipping and I've already had a muffler shop make the outlet round again. It was a bad dent that flattened out a portion of the edge. Hopefully I won't have installation issues with that.


thanks!
I found a solution to warped, weakened header flanges.
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