slant six manifold issues

heviarti · Post by **heviarti** » Fri Jan 27, 2006 9:30 am

I've since managed to fix my manifold, but I was curious if anyone had seen or heard of this:

My exhaust manifold sat up about a half inch at the ends and 1 quarter through the rest above the intake, so bad infact that number one and number six were not fully aligned witht he exhaust ports on the head. I got a different exhaust manifold, figuring mine was warped. after bolting it together(finger tight) I found that it sat about the same. So, I bolted everything up loosely, and pulled the head side to five inch pounds before the manifold joint. The side of the joint facing the fender was contacting, and the side of the joint facing the block had about an eighth of an inch gap along it.

I filed some material off it, and got it reasonably lessened, but still not ebough for the metal gasket to seal it. I ended up making a brass bail that was wedged on the legs, and fitting it in the channel on the crush gasket.

The two big mopar people around here had differing opinions, both of which I know are wrong. One suggested my head was warped, and seeing as a head generally warps only .002 or .003 along that surface that can't be right. The other suggested I had a manifold for an EGR valve, and was missing the spacer. I specifically searched out the manifold for an early slant six, plus a 1/16 inch spacer as clearance for an EGR valve makes no sense.

Has anyone seen this condition before, or have a correct solution for it?

Daddiojoe · Post by **Daddiojoe** » Fri Jan 27, 2006 12:53 pm

The knowledgeable folks at http://www.slantsix.org will be able to help, I'm sure, but let me tell you about my experience.

I had kind of the same problem after I took my manifolds in, bolted together, and had a machine shop even up the surfaces and also grind the bottom exhaust flange. I couldn't get the manifolds bolted to the head for love or money.

Took it back to the shop, wondering what they did, and they suggested I loosen up the bolts holding the two manifolds together then bolt them to the heads. It worked.

So--are your manifolds still bolted together? Loosen them up, mount them on the heads, and then tighten them back together.

You really don't want the manifolds too tight on the head, like 15 ft lbs: it slides back and forth a little bit.

Hope this has helped. If not, go to http://www.slantsix.org

Good luck,

Joe

heviarti · Post by **heviarti** » Fri Jan 27, 2006 1:14 pm

no, I parted them..

Jeffc · Post by **Jeffc** » Sat Jan 28, 2006 12:42 am

Bolts holding the two together must be loose before you bolt the intake and exhaust mans to the head if the two have been parted.
Tork the intake and exhaust down, then the bolts that hold the two together is SOP.

Only way it works well...........

If they have never been parted, just bolt them up as is..... and hope the mated surfaces on the intake/exhaust man don't leak

73_Adventurer_Sport · Post by **73_Adventurer_Sport** » Sat Jan 28, 2006 6:28 am

What you have is a very typical situation with slants. On the last one I put together, the misalignment between manifolds was about 1/4".

I replaced the thin, metal gasket between the carb heat box and exhaust manifold with one I made out of high temp gasket stock. That helped the vertical alignment. Then I bolted the manifolds together and took it to a machine shop and had the mating surface trued. They had to take off about 1/8" in places. That resolved the twist. I also had to slightly slot a couple of the exhaust manifold holes to keep them from binding on the studs.

It's extremely important to install the PROPER nuts and washers exactly per the service manual. The extreme warping condition you found was likely the result of not doing that. Usually they break when not installed per the book. The manifold must be installed so it can float when it expands and contracts.

Another solution is to get a cast iron header from Doug Dutra, the guru of all things slanted.