Engine Rebuild

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The previous owner reassured me that the Jeep started and ran. As we started to pull it up onto the trailer for the long trip back home, it in fact did start, but barely ran and we needed to push it onto the trailer. A mixture of gas and oil was pouring out of the rear of the engine - suggesting a blown fuel pump diaphragm among other things.

The engine was a total mess glued together with thick oil and rust. The water pump was shot and the radiator fan had a serious wobble, the coolant tank was missing, and the AC was devoid of any freon. The heater hoses were a patchwork of bits and pieces and a used battery kept things lively. A compression check showed that most of the cylinders had between 125 and 145 psi - except for 170 psi in cylinder number 8. A thorough steam cleaning and degreasing helped little. We decided at this point that it would be better to take out the motor for a complete overhaul.

We were shocked by the amount of coked oil that had collected under the intake manifold heat shield and in the valley. Several of the water jacket passages were almost completely clogged with scale.

After the heads were removed we discovered evidence of a blown head gasket (that explains the high compression on cylinder 8). The walls were deeply worn and the pistons were scorched. We packed everything up and sent them off to the machine shop for hot-tanking and a rebuild. The cylinders were bored .040" over and the block was line honed and slightly decked. The bottom end was relatively intact - the crank was in good shape (it was already 0.10" undersized from the factory) and only needed polishing. The rods were cleaned, sized, and reused. The heads were completely rebuilt with new Edelbrock springs and retainers. The valves were treated to a triple angle grind and new seats were installed.

The engine bay was stripped, cleaned, and repainted semi gloss underhood black.

The engine returned in fantastic condition. The block was degreased and washed with soap and hot water before being reoiled with WD40. The machinist had already installed new cam bearings, freeze plugs, and pressed the piston rods onto new cast pistons.  The engine was rebuilt using  Edelbrock's Performer  RV cam that was degreed to neutral advance, Edelbrock's double roller timing chain,  Performer manifold, and 750 cfm Quadra-Jet carb.  A standard rebuild kit was used using Felpro gaskets and seals, a high flow Flowcooler water pump, low restriction 180 degree Mr. Gasket thermostat, and a Melling high flow fuel pump. The ignition was treated to a rebuilt distributor with a cap spacer and cap from a Ford F350 with the 460 engine. The ignition will be upgraded to a high energy unit using Ford's TFI coil system and a HD Duraspark box. With the exception of the PCV valve, all the remaining emissions equipment was tossed.

The A727 TorqueFlite transmission leaked heavily. It and the NP208 transfer case were brought to Jeff's 4X4 for rebuilding. Jeff called later to tell me that unfortunately the tranny's tailshaft housing and rear drum was irreparably worn due to lack of lubrication. I was surprised, especially since the PO had told me that the tranny was just rebuilt. Jeff said that probably the tranny lines, radiator cooler, and torque converter were never cleaned of metal shavings and debris before the first rebuild. He was able to rebuild the tranny from parts from a scavenged Dodge unit. A complete rebuild kit along with a shift kit and valve body job was done, and a new converter was ordered. Happily, the transfer case was is good condition and only needed to be resealed.

My friend Ernie (the Big E) Prevedel was indispensable during this rebuild - volunteering his time, space, parts, and sweat to help me with this first engine rebuilt project. Here he is supervising us reinstalling the tranny

And here is the mated engine and tranny with a set of Ceramic coated Hedman Hedders installed. 8.5mm MSD wires and Champion plugs were installed. There were a couple of missing teeth on the flywheel, but since we didn't have another one we decided to chance it. The original starter seemed to work well, so it was left intact.

All the engine and tranny mounts were replaced with polyurethane units from Daystar. Dropping in the engine and tranny was easy, and the headers cleared without any difficulty at all (whew!). 

Here's what it looked like just before the hood went back on.

It took a little time to custom bend new metal fuel hose to connect to the Q-jet carb. Be sure that a OEM fuel filter is used, and check to be sure that the filter's return port is positioned above the input port. Unfortunately, Q-jets have been long out of production, and my choices were to scavenge one from the junk yard, buy a rebuilt unit from JET Technologies, or buy a new unit manufactured by Weber for Edelbrock. JET's smallest carb was 800 cfm, so I went with Edelbrock's smallest unit that was rated at 750 cfm.  This model is not available with an electric choke, and did not have the bosses necessary to adapt a junkyard choke to the carb body. After a little fiddling, a custom linkage bracket was made for the throttle cable, and a manual cable choke as added. This Q-jet is really supposed to be used as an OEM Chevy replacement, using all the original vacuum fittings from the original carb. There were more than enough vacuum ports to power the vacuum advance and power brake booster - although I had to find a 1/8" vacuum fitting to connect the booster hose to the back of the carb. An Edelbrock air/fuel mixture was added to help fine tune the carb, and the corresponding bung for the oxygen sensor was welded onto the passenger side header collector. To top it all off, a 14 inch cast aluminum with "JEEP" casted onto it was ordered from MOPAR, and the original paper element was soon replaced with a K&N unit.

The powersteering pump and reservoir appeared to be remanufactured units that were relatively new, but the alternator was rebuilt. The radiator fan's clutch was replaced, and a *new* OEM fan shroud was purchased from MOPAR for $50 (I hear that there's still several dozen left at a parts depot in Orlando Florida!).  A B&M 19,000 lb tranny cooler was also added, along with a B&M tranny temp sender unit and gauge. New hoses and belts were used wherever possible.

All the electrical leads connecting the battery, solenoid, and alternator were replaced with 0 or 1 gauge units and carefully routed clear of the headers. Grounding was done with two beefy 4 gauge braided straps that connected the engine to the body and frame. An Optima yellow top deep cycle battery was installed.

I wanted to keep the AC (this IS Florida, you know!), but wanted to convert to R134a refrigerant. The original York -style compressor had seized, but I was able to buy ($$$$) a rebuilt York, and had the condenser, evaporator, drier, and hoses replaced with new units.

The engine was filled with oil and primed before it was installed, and started up with the first crank. The engine was ran at 2000-2500 RPM for 30 minutes to break in the cam, then the oil and filter were immediately changed. The Jeep was then driven cautiously for 500 miles before another oil change, then driven normally for another 500 miles.

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