I need to replace the front ex manifold on my v6. I got a new ie used, set sometime ago but when I looked at them, the condition of the face that fits flush to the cyl head is not that great on a couple of the flanges. Thres some corrosion and pitting on them. There's also a slight twist to the middle flange in that it does not lie in line with the other two.

Will the ex gasket be enough to make up for the corrosion and will the bolts pull the twisted flange straight or would I be better off finding another set of manifolds?

Thanks

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Anything I might say is probably worth what you paid for it, so treat it accordingly!

Dave

www.ltlfrari.com

You will probably break a weld when you torque it down. Check with a machine shop. They can re surface the manifold to make everything flat (if enough material is available).

A buddy of mine uses a large belt sander to reface/realign the flanges on 2.8 exhaust manifolds. I believe he holds the sander upside down in a bench vise and carefully sands the three flanges at once... but it may be the manifold that's held in the vise. The results are great.

rust etc on flanges won't matter much and just sand/grind most that off of it... Twisting is the main problem and can/will likely break when mounted. If not now then metal stress from twisting will cause it to break, often soon.
GM for V6 used welded tube manifold about same as Header but not like Headers on many other engines that often have enough tubing between weld joints to take odd loads for heat cycling etc. V6 exhaust manifolds break very easy to start. If flanges are > 1 to maybe 2 mm out of flat plane then forcing flanges to the head will likely stress the part causing fail.

Manifold "Gaskets" won't "eat" much space to make up the difference for un-flat surfaces. Many can barely seal a flat surface on exhaust parts.
Example: 87+ L4 exhaust gasket is a very simple stamped metal piece.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave