Exhaust Manifold bolt holes will not line up! Can't figure it out for the life of me!

[Techlight]

Hey all

So I'm in the middle of finishing up a crate motor install on my 84 CJ7 AMC 258 i6 / 4.2l i6.

I went to install the exhaust/intake manifold and couldn't get the bolt holes to line up for the life of me. I put the two center top bolts in a few threads and one outer bolt all the way to the side and when I do that the bolt on the far side is out by about a 1/8 to 1/4 inch and one of the other flanges is overlapping one of the bolt holes. Of course no positioning or prying would work at all.

My original exhaust manifold was cracked so I bought a used one with same casting #'s etc. They both have the lining up issue. Now here is where I think it gets weird personally: Neither manifold will bolt up to the original motor either...which has me stumped. I took the cracked one off the old motor myself a few weeks ago so I know it fit.

Any help would be greatly appreciated.

The only think I can think to do is grind/file/cut so that the holes line up properly, but I don't know if that will cause me more grief later or if I somehow have the wrong exhaust manifold or ?...

Thanks in advance for any help...appreciate it.

 

[Rube83]

The old manifold will expand and contract from heating and cooling all the time and will not end up being like a new one. Usually involves a lot of prying to get it on.

 

[Busted Knuckles]

This is not uncommon on cast iron mainfolds, they sell threaded spreaders for other brands, to adjust the manifolds for re-installation.

You probably need to make your own tool, to spread them wide enough to get the bolts in.

To give you some idea :

http://www.amazon.com/Lisle-13000-Manifold-Spreader-Chevrolet/dp/B0009OR94W

 

[Torxhead]

You will probably will have to come up with a combination of methods including the tool or something like it that Busted Knuckles listed. With enough force that cast iron will move around some. Included with a couple of studs to set it on and drilling out a few holes. Cussing and drinking beer is optional.

 

[Techlight]

Well, it's good to know I'm not crazy haha...I assumed it was out of shape from heating cooling but wasn't sure. I'll try the to find a spreader and if all else fails I'll grab a new manifold.

Thanks again for the answers...

 

[IOPort51]

I am always surprised when people are doing anything with a AMC 258 i6 / 4.2l head that does not involve the words boat and anchor. The 4.0 is such a major improvement that using a AMC 258 i6 / 4.2l head is a waste of time and money.

BUT

I think if I were in your situation I would start by lining up the gasket on the head and the manifold and see how much of a difference you had and how much time with a die grinder and a carbide burr it will take to make it happen. I would shy away from anything that worked on the idea that cast iron will bend, it won't, it will break.

 

[Techlight]

Ended up buying a new manifold and only had to grind one part that was overcasted. That and I had to paint it since it was bare cast iron (we'll see how this turns out haha).

On the head swap I have heard of it but haven't read much about it since I bought a long block with a 7 year warranty I don't plan on any engine mods for awhile. I'm in California too, so swapping things that effects emissions is usually something I avoid like the plague.

Although, I would love to do the EFI conversion...if only I had 1200 or so bucks laying around haha. Then there's that peskey YJ leaf conversion and lift I need to do, as well as ditch my AMC20 and my T-5 .

To be perfectly honest I'll just be happy to be behind the wheel of a Jeep again...I'll wheel it for awhile and either restore this one or get another one to tear apart with my boy. Probably the latter.

Thanks again for all the help.