Overland Vehicle Outfitters

Project Flatfender: Engine

The 1970 CJ-5 Renegade came from the factory with an optional "Dauntless V6" engine, a 225 cubic inch (3.7L) 90-degree V6 of an odd-fire design.  Up until the mid-60's the Jeep "Universal" models relied on the durable L- and F-head inline four cylinder engines that were adequate to the task, especially off-road, but were never accused of offering "inspired" performance on the street.  Kaiser Jeep's primary competition in the small 4x4 utility segment was upping the ante in the form of V8 engines being offered in the Ford Bronco and International Harvester Scout.  To remain competitive, Jeep needed an optional performance engine for the Universal line.  The AMC acquisition, and subsequent switch to the excellent 232 and 258 cubic inch inline sixes, was still a few years away, and would require a slight stretch of the wheelbase to accommodate the longer engines.  So Kaiser Jeep began looking for an existing compact and powerful engine that would forego the large investment of time and money to develop an engine of their own.


Enter the Buick V6.  It had first been installed in the 1962 Buick Special as a 198 cubic inch 90-degree V6 dubbed the "Fireball".  This engine was a derivative of the aluminum block 215 V8 from Buick, and was essentially a shortened version of that V8.  This is what gave the engine it's unique odd-fire design, so called because of its unevenly spaced firing impulses.  Buick increased the bore, bumping displacement to 225 cubic inches, in order to match the bore of another of its V8 engines (the 340).  Kaiser bought the rights and tooling from Buick and, in 1966, introduced the engine in the Jeep CJ line as the "Dauntless V6" making 160 hp and 235 ft lbs of torque.  The engine was a great match for the Universal Jeeps and offered a dramatic increase in performance.  It sold well and continued to fill the role of Jeep's performance engine through 1971, when AMC replaced it with its own inline sixes. 
Dismantling the engine began with lifting it free of the chassis with an engine hoist, and then bolting it to an engine stand for ease of disassembly.  Having no experience with this engine when it was in running condition, I was anxious to see what condition its internals were in.  I removed the external engine accessories such as the alternator, starter, fan, clutch and pressure plate, and exhaust manifolds.  I then moved on to the oil bath air cleaner assembly and the carburetor before draining the antifreeze and engine oil.    





One thing quickly became apparent after removing the valve covers and oil pan - there was a large amount of metal particles in the engine oil, oil pan, oil pickup screen, and surrounding the rocker arm assemblies.  You can clearly see the abundance of shiny metallic flake in the pictures below.  This was a clear indication of excessive wear of internal engine components.    






Continuing with disassembly, I removed the timing cover, intake manifold, and the rocker arm assemblies.  This allowed removal of the pushrods and hydraulic lifters.  Next were the heads themselves, and then the camshaft and bearings.  Finally, I removed the block plate that houses the rear main seal, and then the crankshaft and crank bearings.  With all of the major components removed, the next order of business was to clean off the 40+ years of accumulated gunk and grime.  I used a friend's industrial parts washer and, after several cycles, the components were ready for a detailed inspection, which began to tell the story.
The rocker assemblies, especially the shafts themselves, showed excessive wear in the form of deep grooves from the rocker towers, springs, and rocker arms.  (This probably accounts for the majority of the metallic particles in the oil.)  At least two pistons had cracked oil rings, and several cylinders showed significant scoring as well.  But the biggest issue I uncovered, and probably the reason the engine gave up, was that the timing/front housing cover had cracked near the oil pump assembly.  This cover is aluminum, so the prior owner had attempted to seal it from the inside with epoxy.  It must have held up for a while, but the epoxy had become brittle and pieces were breaking off and being sucked through the engine.

The camshaft and lifters showed normal wear, but would need to be replaced.  (Whenever you install a new camshaft, you need to install new lifters at the same time.)  The pushrods were all straight and true and, after a little polishing, the ends were smooth and shiny.  The crankshaft appeared to be in good shape.  The front housing cover, in addition to the aforementioned crack, also showed excessive wear at the oil pump and at the front of the camshaft.  This aluminum timing cover is a critical component, as it serves as the mounting base for the oil pump, oil filter housing, water pump, fuel pump and distributor.  Obviously it would need to be replaced.  The bottom "ear" of the aluminum alternator bracket had also broken off, necessitating replacement. 





Now that I had a good idea what I was dealing with, it was time to begin the rebuild process, and this meant starting with the machine work.  I had spent a considerable amount of time researching local automotive machine shops through online research and reviews, talking with fellow gearheads, and seeking out recommendations from friends who have built multiple race engines.  I settled on a shop located in West Liberty, Ohio, called Wilgus Automotive Machine.  The owner, John Wilgus, has been in business for decades building all types of gas and diesel engines for street and race applications.  After discussing my application and engine needs, John helped me develop a plan and provided recommendations for parts.  I decided to have John order a complete engine rebuild kit, consisting of top shelf parts from manufacturers like Fel-Pro, Hastings, Clevite, Silv-O-Lite, Sealed Power, and Melling.  This would be cheaper and more effective than trying to piece together the right parts for compatibility. 
I dropped off all of the major components to be thoroughly cleaned, inspected, checked against OEM specs, and magnafluxed (where applicable) to check for cracks.  In the end, the block and heads were in good shape.  The block was bored 0.030" over due to normal cylinder wear.  The heads were treated to a full refurbish including reground or new (where needed) valves, new valve guides and seals, retainers, springs, and hardened seats.  This last point is critical for longevity - using the original valve seats with today's unleaded gasoline can cause rapid deterioration.  (Remember that in 1970, leaded gasoline was the norm.)  I had John reassemble the valvetrain in the heads while he completed the other machine work.  When the block and heads were completed, they looked better than new.  






The crankshaft was found to be true, and only required polishing of the journals.  This would save me quite a few dollars vs. replacing the crank.  The piston connecting rods were also true and crack-free and could be fit to the new Silv-O-Lite pistons and Clevite bearings.  An interesting note about the connecting rod caps; when refitting the cap to the connecting rod, it must be oriented in the right direction.  There is a mark on each half of the cap, and these must be lined up, which will ensure that the oil hole will deliver the needed lubrication (see picture below).  The pistons themselves are a deep dish aluminum design similar to the OEM pistons.  This design uses two compression rings and one oil control ring per piston. 





With the bare block awaiting, the first order of business was to install the crankshaft bearings.  These are indexed for easy reassembly in the correct position in the block and in the bearing caps.  It's critical to thoroughly coat the bearing surfaces with Permatex Ultra Slick Engine Assembly Lube or equivalent (engine oil alone won't provide the same level of protection) to protect from excessive wear at initial start-up.  Next came the installation of the rear main seal components.  Note: the original rear main seal utilized a two-piece rope packing (see picture below) that was meant to accommodate a wide range of machining tolerances.  While adequate for the time period, I chose to use a more modern alternative from Fel-Pro incorporating a two-piece molded rubber design.  Use extra care on the installation of the rear main seal and follow all instructions closely - this is not a job you want to repeat due to oil leaks.  This multi-part seal design requires use of assembly lube, grease, and RTV Silicone in specific locations.  Again, you can't be too careful here.
For extra insurance, I used assembly lube on the crankshaft journals as well before setting the crankshaft into place in the block.  When working with the crankshaft (and camshaft) be very careful not to nick or damage the polished surfaces during installation.  Prior to final installation, it's recommended that you use Plastigage to measure tolerances between crankshaft and bearings to ensure they're within spec.  With the crankshaft in place, I bolted the four main bearing caps in place and torqued them to spec.   






At this point, it was time to rotate the engine to its right-side-up position and install the rings onto the pistons and the piston/connecting rod assemblies into the block.  I purchased a piston ring compressor tool at the local parts store, installed the rings, then lubed the cylinder walls in preparation for installing the pistons.  The tool made it easy to compress the rings sufficiently to slide the piston/rod assembly into the cylinder.  The difficult part is ensuring the connecting rod doesn't damage the cylinder wall and crankshaft journal as you slide it into place; having an extra set of hands to assist makes this process much smoother.  Once the connecting rod is positioned properly on the crankshaft, and the bearing halves in place, position the female end of the rod/cap into place and hand tighten the cap nuts.  It will be more difficult to access and tighten some of the nuts due to the position of the piston on the crankshaft, but with a little care it can be done.  Be sure to go back and torque all of the nuts to spec as the final step. 
At this point I decided to button up the bottom of the engine.  This meant installing the small oil tray and the oil pickup tube before installing the oil pan gasket and oil pan.  Along with a high quality gasket, I chose to coat the block with Hi-Tack sealant to both seal and hold the gasket in place during installation.  I also coated the pan side of the gasket with sealant before torqueing the bolts to spec. 





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Overland Vehicle Outfitters
Marysville, OH 43040