Exhaust

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The Chief originally came from the factory equipped with a single 2 1/8" exhaust running through a catalytic converter. The previous owner had removed the converter and altered the Y-pipe to create dual exhausts. The mufflers were staggered in offset. The entire system was severely rotted, so it was all gutted.

My plan was to run dual exhausts and headers. Doug Thorley makes a set for the Wagoneer/Cherokee, but their cost was outrageous. I had heard some good stories about Heddman Hedders and ordered a pair of inside-the-frame headers. Because of concerns about heat transfer I paid the extra to have them factory ceramic coated. This caused a delay in delivery and I eventually got them 6 weeks later. 

After dropping in the motor, the headers were installed using dead-soft copper gaskets from Mr. Gasket. I had purchased a set of Stage 8 locking header bolts, but found that the set spec'd for AMC motors didn't fit because the outermost bolts were of a different size than the inner bolts. I called Summit Racing and they sent a set spec'd for AMC *Jeep* motors, complete with the two different sized bolts. The locking tabs of each bolt had to be custom ground with a Dremel to fit the specific bolt location. I like the design of the Stage 8 bolts - these stainless grade 8 bolts not only have the usual 7/16" hex head, but also an inner recess for an Allen wrench in those situations where a box wrench won't fit. All the bolts were accessible - even the number 8 and 7 bolts (which had to be accessed from under the wheel well). 

Aluminized 2 1/4" tubing was used throughout. Due to the location of the gas tank on the driver side frame rail, both  exhausts would have to be shifted to the right of the driveshaft before exiting out the left and right rear corners. The passenger side exhaust went smoothly, but the driver side needed some fancy rerouting. Contrary to where the original Y-pipe crossed just in front of the tranny pan, the additional length of the header collectors made it impossible to duplicate this path. I couldn't run the driver side exhaust over the front driveshaft for fear of interference during max suspension travel.  Fortunately, the 2" body lift had created enough room to run the pipe between the inside of the driver side frame rail and the tranny and transfer case. It was then bent to run under the u-joint at the rear output of the transfer case before joining up with the passenger side tubing. Needless to say, it was impossible to run a crossover pipe between the two exhausts - we'll have to see whether this will affect the noise and performance later on....

A pair of Flowmaster mufflers were used, mimicking the original setup by using one with a offset input and center output, and another with a center input and offset output. I really wanted the exhaust to highlight the engine mods with a throaty roar, but had concerns about possible resonance problems within the interior. I ended up selecting a pair of 50 series Delta Flow Flowmaster mufflers. From there the pipes run to the rear crossmember  before turning an exiting over the top of their respective frame rails and dumping out the rear corners of the Chief.  Fortunately the space remaining, where the original spare tire was stored, was enough to allow eventual placement of a 8 gallon air storage tank for powering impact wrenches and the front ARB locker.