Engine & Exhaust

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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.

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 pictures 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 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. 

With the bottom half of the engine addressed, I moved on to the new camshaft.  Installation of the camshaft bearings and camshaft was a similar process to the crankshaft and was straightforward, although care must be taken when sliding it into place so as not to damage the machined surfaces.  After coating the hydraulic lifters with assembly lube, I dropped them into their holes to rest on the cam lobes.  

As mentioned above, I had John Wilgus reassemble the the heads after completing the machine work.  I installed the heads with the high-quality head gaskets provided, torquing the head bolts to spec in the proper sequence per the factory service manual.  Once installed, I was then able to insert the pushrods and reinstall the rocker arm assemblies.  Because the rocker shafts were seriously worn, I purchased all new shaft assemblies for installation.  I used assembly lube on each of the rod ends for start-up, as well as the end of each valve, and also liberally coated the rocker assemblies. 

The intake manifold, which spans the valley between the engine's heads, was thoroughly cleaned in a hot dip tank along with the rest of the engine parts.  The engine kit provided a new gasket set for properly sealing the intake manifold.  I was careful and deliberate when seating the manifold to ensure a leak free seal.

A few words are in order regarding the new timing chain cover.  I contacted TA Performance in Arizona for one of their reproduction covers.  TA Performance is the go-to for Buick engine parts, and their knowledge and expertise on the odd-fire 225 V6 was extremely helpful.  They have many parts you can't find anywhere else, and their catalog offerings are extensive.  Their reproduction timing cover is machined to exceed OEM tolerances and comes with the neoprene seal already installed.  All the components that mount to the timing chain cover (oil pump, oil filter housing, water pump, fuel pump and distributor) aligned and installed perfectly.  TA Performance also offers a new camshaft bumper consisting of a spring and thrust washer; I installed this to prevent unnecessary wear on the inside of the timing cover.  The engine kit included a new timing chain and new oil pump components.  I also purchased a new set of timing chain dampers from TA Performance to replace the originals.  TA Performance also supplied a new distributor hold-down bracket and timing cover bolts to replace a few broken originals.

I decided early on to ditch the original oil bath air filter assembly.  While effective, it took up a lot of space in the engine bay and would be a challenge to shoehorn into the flatfender body.  Instead, I purchased a top mounted chrome air filter assembly that accommodates a low profile K&N filter.  For the carburetor, I purchased a Rochester 2G rebuild kit and Power Valve, and completely rebuilt the carb.  

I wanted to upgrade the original distributor to a late model HEI distributor for hotter spark, increased performance, and reliability.  I chose CRT Performance for their HEI distributor kit and a set of 8 mm performance wires.  This kit comes with an integrated ignition coil and control module in the cap.  

This is the first complete engine rebuild I've done, and it was a very satisfying part of the overall build.  Now that it's finished, there are several key take-aways.  First, don't skimp on the quality of the engine components.  The engine kit I used was made up of parts from the finest manufacturers -  Fel-Pro, Hastings, Clevite, Silv-O-Lite, Sealed Power, and Melling - all are well proven over many years.  Second, make sure you research the machine shop you choose; you want a shop with years of experience that won't cut corners.  I have the utmost confidence in Wilgus Automotive, and have returned to the shop for engine work on other vehicles.  Lastly, while you're deep into a rebuild, take the opportunity to upgrade parts for strength, performance, and longevity where it makes sense.  The engine's already torn down, so it makes sense to install better parts (water pump, alternator, distributor, headers, etc.) while everything is accessible. 

When it came to selecting a muffler, I looked to Gibson Performance.  I've installed Gibson exhaust systems on many project and personal vehicles, and find that they are well made and offer a deep, mellow tone without excessive highway drone.  For this application, I chose an stainless steel performance muffler (#BM0106) that utilizes a fully-welded, straight-through design for maximum flow and performance.  This design doesn't incorporate packing baffles or weak deflectors that can fail over time, and the thick welded case will stand up to off-road abuse.  

To finish off the system, I looked to eBay for a Y-pipe, clamps, and hangers.  I used an assortment of stainless steel lap joint and stepped band clamps from Blackhorse Racing, as well as their dual-to-single Y-pipe connector.  I also purchased a set of 5 heavy duty rubber exhaust pipe hangers, and fabricated a few mounting brackets to attach them to the frame.  I spent a lot of time measuring, cutting, test-fitting, and repositioning before I arrived at the final solution.  My MIG welds don't compare aesthetically to robotic or TIG welded seams, but they're sturdy and solid enough to stand up to the rigors of the trail.  When routing the exhaust, I ensured plenty of clearance to prevent overheating of any adjacent components and to ensure a rattle-free system.  I designed the system into 4 sections that can be unbolted for future maintenance or replacement.  Note: even with the slip-fit tubing sections, I found it necessary to use parallel relief cuts at the joints to allow the band clamps to compress the tubes together sufficiently for a tight seal.  As additional insurance, I applied exhaust pipe sealant to the joints.