Drivetrain and Suspension, Version 1


Engine #1- AMC 360

When I bought the truck, the engine was untouched and original. Well, make that unmaintained and original; based on the buildup of burnt oil under the valvecovers, I should probably add a "1" before the 90,000 miles showing on the odometer. It did start and run, but smoked badly from the tailpipe. Unclogging the oil drainback holes in the head eliminated that problem; they were so clogged that a quart of oil dumped out from under one valvecover when I removed it! Oil pressure hovered somewhere between bad and low, and the incessant valvetrain tapping was a constant reminder that this engine's days were numbered.

My eventual plans to rebuild the engine were moved up the agenda when a lifter self-disassembled itself into the lifter valley when I was replacing a pair of rocker-arms. The solution was not a full rebuild, but a good-running 90,000 mile 360 from a 1979 Wagoneer Limited parts-truck. The engine itself was used, but very clean inside and certainly useable. The main bearings plastigaged to within specs, so I replaced all the gaskets and seals but left the bottom-end alone. One valve was flawed, so I replaced it and had all the others ground. I cleaned up the casting-flash in the ports, and added an Edelbrock Performer Plus camshaft, lifters, timing-chain and valvespring set. I used stock exhaust manifolds covered in Plasticote High-Heat pain. The radiator was an old three-row I had hanging around, but even with a worn clutch-fan, the engine temp consistently ran below the halfway mark in the green zone on the temperature gauge.

The stock Motorcraft 4350 4-barrel carburetor used a unique spreadbore pattern (very different from a Quadrajet; click here for information and pictures on adapting an ordinary squarebore carb to the oddball Motorcraft pattern), so when it was eating up too many accelerator-pump diaphrams (and I was tired of special-ordering $25 carburetor rebuild kits just to get the diaphram), I bought a TD-Performance #2199 adapter to mate a Holley Model 3310 750cfm vacuum-secondary carburetor to the oddball spreadbore intake. A couple weeks later, I traded an axle for a core 360 that came with an Edelbrock Performer non-EGR intake manifold, so I eventually (a year later) installed that with the nice 12-pt ARP stainless bolts that came with it, and have done away with the original intake/adapter combo.

The 750cfm Holley was one I happened to have lying around at the time, and after hearing so many horror-stories of this carb flooding or bogging off-road, I took preventative measures before I installed it. First off was a pair of Holley off-road needle and seat assemblies for my center-hung float-bowls; they use spring-loaded tips to smooth out any bobbing of the float in the bowl (kind of like little float shock-absorbers). Next up was a pair of extended jet pickup tubes accompanied by a notched float. I installed the "whistle"-style anti-slosh vent tube that came with a Holley Trick-Kit from years back, and also installed an anti-backfire power-valve blowout protector. Finally, I ran some 1/4" fuel-line in an arc from one bowl vent across to the other, with an opening cut in the middle, so that any fuel that sloshed up wouldn't go down the carb throat.

This carburetor was really bigger than an optimally-sized piece for this engine, so it took a bit of tuning to make it work right at part-throttle. I originally started with #68 jets on the primaries (I left the stock secondary metering-plate untouched), but was left with quite a bog in the transition from the idle to the main fuel circuits. I replaced the original #25 accelerator-pump squirter with a #37, installed a blue accelerator-pump cam on the #2 screw position, and upped the jetting to #70's on the primary side. This removed the bog entirely, and the carb performed flawlessly off-road at virtually any angle. Bumping the truck over rocks while blipping the throttle on and off didn't upset it at all.

I then replaced that #3310 carburetor with a #9834 600cfm single-feed vacuum-secondary Holley with side-hung floats. I ran #66 main jets, a stock rear metering plate, and off-road needle and seat assemblies, along with the extended fuel-vent hose. The pink accelerator-pump cam that it came with produced a bit of a bog, so I put in a blue cam on that #2 screw setting, and the bog disappeared (that seems to be the trick on this engine).

I had this carb off-road at severe angles, I can say that it performs very well. It doesn't stumble at odd angles, and the only time it ever stalled was the suddent stop at the bottom of this descent, due to a momentary exposure of the fuel feed lines:

Nevertheless, it started right up and I just kept going.

Driveline #1: TH400 3spd Auto Transmission and Borg Warner 1339 Quadratrac Transfer Case with 2.57 Low-range

The transmission and transfer-case were rumored to have been rebuilt by the last owner who had it on the road; the chain in the Quadratrac case was nice and tight, and the center differential worked great, so I'm inclined to believe they've seen some work. The Emergency-Drive vacuum lines were missing upon arrival, so I  fabricated a new set to take full advantage of all the transfer-case modes.

Still, there was some banging coming from the transfer-case under high-load conditions; since the chain is perfect, this points to the splines on the clutch cone in the QT differential being stripped out. Instead of repairing the transfer-case, I upgraded to an NP205 transfer case to bolt in to replace the original QT:

Axles and Suspension #1:

I left he stock leaf springs untouched and added a 2" block in the rear to lift the tail up a bit for increased departure clearance. The shocks were a set of Gabriel Light-truck shocks donated by my Grand Wagoneer when she acquired a set of RS9000's. For trail-use, I would unbolt the lower links on my front swaybar; it only took five minutes, but it increased the flex significantly.

The front and rear Dana 44 axles retained their stock 3.54 gearing, which worked fine with the 33" tires, the 2.57 low-range and the torque of the 360. I always carried a spare set of axleshafts and driveshafts, which came in handy when I had to replace a twisted front driveshaft out on the trail. The current front replacement is from an '80-up FSJ that has a much larger cross-section. I didn't realize its original application until after I had already installed it, but it fit like a glove, and the larger diameter had no interference issues with the stock TH400 tranny.

I began with a set of 31"x10.5" Regul Trailblazer AP's mounted on the stock 5-slot rims, which I intended to use as my street tires. the set of B.F. Goodrich 33"x9.5" Mud Terrain T/A's that I had mounted on a set of red 15"x8" wagon-wheel steel rims worked so well on the road that I never switched back. .

On to Cherokee Drivetrain, Version 2

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