Cummins93

Over the years of replacing a few exhaust manifolds I have seen multiple head flange thicknesses.

Ebay China header 1996 xj =0.41"
Ebay China header 1995 xj =0.41"
Rockauto ATP 101330 =0.45"
1996 stock manifold =0.49"

I have also noticed the mopar performance exhaust gasket has metal insert rings for the exhaust ports. Was this ment to take up height for a superceeded thinner exhaust flange thickness?

The issue of the reduced thickness causes a difference in height between intake and exhaust flange landings. This causes an unequal clamping of the washers when torqued down. They are clearly at an angle. Anyone want to measure some manifolds they have sitting around and where they came from?7

Bmoney

1996 i have off is 15/32 with a tape measure.
I can throw some decimal calipers on it.

jessenator

some caliper shots comparing flange' thicknesses

1/2" or 12.8mm is the standard (from the two OEM exhaust manifolds I have).

Just like mine: FAR shy of the OEM thickness. Sent them both back...

Aftermarket exhaust header woes

Cummins93

Has anyone found a stock design with the right thickness? I will try to see what Dorman has next.

jessenator

If you're talking about the modified header design, the 3-2-1 (non-oem) design, Banks is pretty much the way to go. It's the cheapest you'd want to go, at any rate.

For the improved OEM (with expansion areas) i believe the last one (in my old 96) was a Dorman.

I recently went through two ebay chinesium headers and found one of my spare OEM headers that wasn't cracked. Gave up on them.

Cummins93

Dorman oem replacement =0.45

So I took up the difference with some washers I found.

PatHenry

Cummins93 - Can you report back in a few days time with how well that the Dorman manifold is working for you??
I'm planning on replacing the leaky manifold on my 95 in the near future and was contemplating using the Dorman replacement.

Cummins93

Yea I'll update once I have everything done.

The felpro gasket with the metal inserts on exhaust ports did not make a difference in the unevenness of the intake/exhaust bolts. But I will include its info below.

PatHenry

Awesome - thank you sir!

PatHenry

So I pulled the trigger on the Dorman exhaust manifold. I'll make sure to grab a handful of washers to deal with the flange thickness issues.

Cummins93 - Are there are tips/tricks/advice that you have for doing the replacement? This is the first time I'm pulling the intake or exhaust manifolds off - the instructions look simple enough, but they always look simple it seems.

What is the recommendation on the hardware kit - is this necessary or only if I lose/break something?

Cummins93

Report the flange thickness when you get it please. Also the Dorman collector doughnut was not very impressive. It was almost too small on the inner diameter, very tight fit.

I am still having issues with an exhaust leak. While pressure testing the exhaust the only place upstream of the crossmember to have a detectable leak is the collector joint.

My advice is to have an assortment of 3/8 extensions. Mine have the wobble ends on them which helps. A shallow 9/16th or 14mm socket will expose enough threads to hand start all the bolts under the intake manifold. I am able to reach all bolts from the driver side fender. Trying to go from underneath made it more difficult.

PatHenry

I will definitely report on the new and old flange thicknesses.

PatHenry

As far as the exhaust doughnut goes, I'll have a good chance to play with it a bit since I'm also replacing the front pipe. (When I'm done the exhaust will be all new-ish since I had to do the muffler and tailpipe when I first got it.)
My local Autozone has the walker (same brand as the pipe) gasket, so I may grab one and see which works better.

It looks like you welded the washer. Is that the case?
I don't have the tools or knowledge to weld, so I'm thinking I'll probably cut the washer in half and sort of slip it in as if it were on the bolt. (This is assuming the Dorman manifold is the same one that isn't the correct thickness.)

PatHenry

Dorman manifold is far shy of the 0.49" thickness. It appears to be about 0.45" as previously noted.

It's hard to see in the photo but it's about 1/16" shy of

PatHenry

the 1/2" mark.