Leaderboard

Quite often the flange for after market headers is thinner than the original exhaust manifold AND INTAKE MANIFOLD, so it doesn't get clamped down properly in the middle where the bolts have to bridge across both. Have have to shave the ears of the intake manifold down to the thickness of the exhaust so they both get clamped evenly

" these are poorly welded and or warped"... Likely... When we weld a manifold it gets bolted to a head beforehand to minimise the warping. What does a straight-edge along the whole extractor face show? The middle two bent to one side or not parallel vertically?? The best answer would be to get them ground flat right along the mating face, which would be good if it was $100 or less. It would be cheaper to heat the middle pair up with an oxy/acetylene set and twist them to the right place once red-hot. Simple to heat up, but hard to get lined up just right. You could try lightly bolting just the headers on and heating them up, then pulling them flat with the bolts when soft. Unless the bolts/nuts pull it straight and flat, then the gasket will blow out all the time. Was it up to torque when you put the feeler gauge down it?