leaky headers......

There's only one way to fix it up, and that's to take the header off, and either take it to a machine shop, and have them re-surface the flange, OR spend an afternoon with a long flat file, and a straight edge, and file it flat.. I am absolutely astonished at the finished factory flanges for being un-true.

I always check the flanges, new and used, and seldom find a set that are true.

And don't tighten the juice outa them, and re-bend them..