I have been a member here for about a year and have been repairing a 73 Dart Sport using information that I have gotten here. I searched for this answer but came up empty.
I had a large crack in my Slant 6 exhaust manifold. I purchased another exhaust manifold and when I did a trial fit up of the manifolds I found that the intake flanges are about .040 to .050 inches above the exhaust manifold flanges. Both the exhaust and intake gasket surfaces are flat and true and without warp. I don't believe the gasket will seal (maybe I'm wrong).
What I need is information on what to do. Will the gasket seal? Is it going to be necessary to mill the surfaces to even them up? Is there another answer.
I need some advice from people more experience that I.
Thanks
Steve.

Do you mean it's as if the intake manifold runners are a bit longer? If so - have you tried loosening the 3 bolts that hold them together and aligning? There should be some slack in the bolt holes / threads.

I have wiggled the intake to all possible positions and the intake runners are still .040 to .050 inches longer than the exhaust runners. I don't have three bolts to connect the manifolds, I have a stud and two bolts. The hole for the stud doesn't allow the intake to be moved back at all.
Steve

I haven't picked up a stock manifold in some time. The hole the stud goes through - is there enough meat there to just drill (or dremel if your a masochist) it out? Just be careful of the exhaust to intake junction and make sure there's enough surface there to still seal up after the move.

Otherwise, I'd take it to a engine machine shop as a unit and have them surface grind it like they would shave a head/block.

With a stock type gasket I wouldn't risk it. With a thick remflex graphite or Australian gasket maybe, but there's always gonna be that what if in the back of your mind.

Vote #2 to drill-out or grind more clearance into the holes to allow you to shift the manifolds around so you can get good alignment at the port face.
It is a good idea to have the set resurfaced once it is aligned as close as you can get it.
DD

A used stock manifold? Or a 'new' one from eBay?
The new eBay manifolds are Chinese copies and are not even close to being accurately made.

If it's a used OEM manifold, perhaps someone milled the flange. You may have to mill the intake flange to match.

_________________
--> Check out my FI Turbo build <--
--> And the race truck build project <--
--> The Diesel Corvette <--

I appreciate the timely responses. The manifold that I purchased had been surfaced. I checked on getting the assembly surfaced, but the cost effective way was to purchase the matching intake manifold from the original seller. He is local but didn't know that the pair had been machined. Because of the error, he cut me a good deal on the intake manifold and everything is now in the green.
Thanks again to all the responded
Steve