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CHAPTER 3

DISASSEMBLY

With all of the necessary tools and equipment on hand, it’s time to begin complete engine disassembly. Though it might seem relatively easy, it’s a methodical process that should be considered to be as important as any other portion of the rebuild and shouldn’t be performed haphazardly. It not only provides a firsthand look at how engine components interact during typical operation and the slight tolerances between them, it also reveals just how well your engine is functioning overall.

Using your engine’s operating characteristics just prior to the decision to rebuild as a guideline, you might consider more closely inspecting suspect components or those potentially related to the issue for a possible cause during disassembly. For instance, if oil consumption is an issue, check for worn valve guides or irregular piston and/or ring wear. If the engine uses coolant, check the head gaskets for signs of seepage. And if your engine routinely detonates under moderate load, check the piston crowns and combustion chambers for excessive carbon buildup.

This engine’s external appearance doesn’t lend any clue to its internal operating condition. It wasn’t until complete disassembly that I gained a better understanding of why it ran so poorly. A countless number of detailed photographs like this were taken before and during teardown. Such photos can be a great asset when determining where components go during reassembly.

Disassembly also provides the opportunity to gauge the level of care an engine received from its previous owners. Sludge or deposits in areas where oil typically puddles might indicate a lack of regular oil change intervals. Scored cylinder walls or scuffed piston skirts could indicate tight tolerances or careless highspeed operation. Worn main and rod bearings could indicate an oildistribution or pressure-related issue or possibly improper machining. The list goes on.

Pulling the Engine

For this book, the owner prepared his GTO for engine removal at home by working a few hours each night for several days. Detailed pictures of the entire engine compartment were taken from every imaginable angle to use as a visual aid during reassembly. The hood was unbolted, the coolant and oil were drained, and the radiator was removed. The accessories were unbolted and moved aside, the carburetor and exhaust manifolds were removed, the engine wiring harness was disconnected, and masking tape and a permanent marker were used to note each wire’s exact location.

The transmission was supported from beneath by a hydraulic jack, and the torque converter, transmission bellhousing, and motor mount bolts were removed. Using a highquality engine hoist and a length of heavy chain, the engine was lifted up and out of the vehicle while closely watching for any snagged electrical wires, additional pieces that needed to be removed, and sufficient clearance in every direction. Expect to perform a similar process if you’re pulling your Pontiac’s engine.

After deciding to completely rebuild this GTO’s 400, the owner and a helper pulled the engine in the comfort of his home garage. Anything bolted to the engine that could be easily damaged or impede extraction was removed and set aside. Engine removal is different for each vehicle. It typically includes draining the coolant and oil and removing the carburetor, fuel lines, wiring, vacuum hoses, distributor cap and coil, accessory brackets and pulleys, and radiator. Some prefer to remove the transmission with the engine, but that can add several more steps and could make separating the engine and transmission more difficult while it is suspended. I recommend unbolting the transmission bellhousing from the engine, and the torque converter from the flexplate if equipped with an automatic transmission and leaving the transmission in the car. Remove the clutch countershaft from the engine or frame rail on cars equipped with a manual transmission. Unbolt the exhaust manifolds from the engine or the head pipes, whichever is easier. Then, remove the engine mount bolts. Connect a section of heavy tow chain to the cylinder heads or a carburetor flange adapter to a cherry-picker hoist. Lift the engine up and away while the helper watches closely for anything that might snag the engine during lift-out.

Before disassembly begins, remove the flexplate from the engine while it is suspended from the hoist. This prevents damaging it or the ring gear while bolting it to an engine stand. It can be difficult to apply sufficient torque to remove the bolts while the engine is hanging loose. If you have a helper who can prevent the engine from rotating by using a flywheel-holding tool, you can use a long 1/2-inch breaker and 5/8-inch socket. However, I prefer using a 1/2-inch-drive pneumatic impact wrench as opposed to hand tools for this task. Note the orientation of the flexplate in relation to the engine and place the bolts and star washer in a clearly marked bag. If the engine is equipped with a flywheel and clutch assembly, remove the pressure plate first. Watch that the clutch disk doesn’t fall onto your feet as the pressure plate is pulled away! Remove the flywheel in a manner similar to removing a flexplate. Inspect the ring gear for signs of excessively worn or missing teeth. If a flywheel, inspect the clutch contact surface closely for heat cracks. While some can be removed with milling, it’s sometimes easier to start with a new flywheel.

While suspended from the cherry-picker hoist, mount the engine from its bellhousing flange to a high-quality engine stand with Grade-8 hardware. To prevent it from falling over and causing significant damage to itself or anyone standing nearby, have a helper gently lower the hoist while you watch that the engine sets down easily on solid pavement. Units similar to this retail for less than $100, while used stands in good condition can be found for about half that at local swap meets or internet classifieds. A complete Pontiac engine typically weighs around 700 pounds, so you’re safest using an engine stand with a capacity rating of at least 1,000 pounds.

Since this 400 operated normally and didn’t experience catastrophic failure, I didn’t treat its disassembly different from any other. Once the engine was secured to a suitable engine stand, I worked toward the center of it. My first goal was to remove the cylinder heads, which tends to make the engine more balanced, more maneuverable, and much easier to rotate on the stand. I then focused on removing the oil pan, camshaft, and rotating assembly in that order.

Though each example in the Pontiac V-8 engine family shares common characteristics, it seems each variant contains something that’s slightly different. For instance, early engines utilized a reverse-flow coolant system, and the rocker system of engines through the mid 1960s was oiled through its studs. This particular 400 contains neither, and as such, the disassembly steps shown do not touch on them. If your particular engine has one or more characteristics not covered here, I recommend that you consult a factory service manual for that portion.

Component Inspection

As the components were removed from the engine, I closely inspected each for signs of abnormal wear and photographed and noted anything that looked suspect. Each component was stored in a safe and dry location and placed in close proximity to others as it was removed to prevent losing anything. I stored small parts and hardware in clearly marked Ziploc-type bags, photographed each bag, and placed them in a dedicated box or container that remained with major components throughout the process.

I found several issues that I considered areas of great concern during component inspection, and each instance was noted for the machinist. The pistons and combustion chambers were heavily coated with carbon, indicating that the engine was not burning cleanly. At least one of the lifters was irregularly worn, and the camshaft was difficult to remove from the block. The piston skirts had some visible scuffing, and some of the connecting rod bearings were worn to the copper.

The owner and I discussed what was found in his engine and agreed that the decision to rebuild was very timely. It seems that significant damage or complete failure could have occurred at any time without much warning or indication, and that certainly would have cost him even more time, money, and aggravation. The next step was to choose a machinist whose ability was one that we were equally comfortable with to correctly rebuild this 400 and determine exactly what it needs.

Top End Removal

An engine is much more balanced and easier to maneuver when its cylinder heads are removed. That process first involves disassembling the engine’s top end components.

1 Drain Remaining Fluid

Though the fluids were drained before removing the engine from the vehicle, a certain amount inevitably remains in its internal passageways. Just before beginning disassembly, remove the oil filter (if still installed) and the oil filter housing bolts (using a 9/16-inch wrench), and drain the remaining coolant from the water jacket surrounding each cylinder bank by removing the drain plug on both sides. The type of wrench required to remove the drain plugs varies. Drain the oil pan in a similar manner with an 11/16-inch wrench.

2 Remove Valve Covers

Remove the valve cover bolts with a 7/16-inch socket. Lift the valve covers. Place units with a chrome-plated finish into a cloth or in a safe location where they cannot be scratched or damaged. Place the bolts and wire-harness retainers into a clearly marked bag.

3 Remove Coolant Bypass Bolt

Pontiac intake manifolds are sealed to the timing cover and use a rubber O-ring and a long bolt. The intake is used as a bypass to circulate coolant throughout the engine while the thermostat is closed during warm-up. Remove the bypass bolt with a long 7/16-inch box-end wrench for maximum leverage. Rust and corrosion can make the bolt difficult to remove. To avoid possibly breaking it, exercise patience during the process.

4 Remove Intake Manifold Bolts

Remove the 10 bolts that secure the intake manifold to the cylinder heads with a 9/16-inch wrench and place them in a clearly marked bag. Many later engines use studded bolts on either side of the water crossover that serve to secure various accessory brackets. This 400 didn’t use any.

5 Remove Intake Manifold

Use a pry bar to separate the intake manifold from the cylinder heads. Lift the intake manifold up and away from the engine. A typical cast-iron Pontiac intake manifold weighs at least 40 pounds, so be sure to have a firm grip on it during removal.

6 Remove Valley Pan

Remove the two bolts that secure the valley pan to the block with a 9/16-inch socket, and then walk a pry bar around the perimeter of the valley pan. Gentle pressure may be required to break the silicone seal bond. Use care to prevent bending the pan’s thin lip because that could impede its ability to seal if it is reused during reassembly.

7 Remove Distributor

Remove the distributor cap and external coil of a points-type system before removing the engine from the car. Remove the single bolt securing the distributor hold-down with a 9/16-inch socket. The bolt and hold-down are placed in a clearly marked bag. Lift the distributor up and out of the block. Rotate the distributor housing while lifting it; this can make removal a bit easier.

How to Remove a Stubborn Distributor

Distributor removal should be as easy as grasping the housing and gently lifting it upward and out of the block. But years of sludge buildup around the base can make the process much more difficult and make extraction seem practically impossible.

Some hobbyists have tried prying, twisting, or hammering on the distributor housing, only to find that it’s bound in the block even more than before. Or worse, it’s inflicted major damage to the distributor itself. There’s a very simple solution that can remove much of the frustration surrounding a stuck distributor, and it includes a $2 can of brake component cleaner and some patience.

Brake component cleaner is a powerful solvent, and a can of it is useful when removing a distributor that’s stuck in a block. Instead of prying on the distributor housing and risking damage, simply lift the distributor out of the block as far as reasonably possible and spray a liberal amount of brake component cleaner around the base. Wait a few minutes for it to soak in, push the distributor back into the block, and try removing it again. It may take a few attempts and a few applications of brake component cleaner, but persistence and patience pays off. The distributor eventually comes out and can be cleaned up appropriately.

This trick isn’t limited to an engine that’s on a stand; it can be performed in the same manner on an engine that’s still in the vehicle. Just remember to change the engine oil to remove any contaminants before starting the engine. ■

Valvetrain Disassembly

1 Remove Oil Dripper

Most production Pontiac V-8s produced through the early 1970s used a bolt-on oil dripper to lubricate the rocker arms, while a version that was welded on to the valve covers was used later on. The bolt-on type is fastened to the studded head bolts and is commonly discarded or forgotten during rebuilds that lack attention to small details. Remove the retaining nuts with a 9/16-inch socket.

Aftermarket Rocker Arms

Pontiac developed the stamped steel rocker arm assembly for the new V-8 it introduced in 1955. Comp Cams produced these roller-tip rocker arms, which were a popular upgrade during the 1990s. The roller tip is intended to reduce the side loading that causes valve guide wear. The roller tip rocker otherwise installs and functions just like an original.

2 Remove Rocker Arms

Remove the nut securing the rocker arm pivot ball with a 5/8-inch socket. Inspect the contact surfaces of each rocker arm and pivot ball for pitting or galling. Because the rocker arm and pivot ball wear in together and self-adjust to each other, it’s best to keep each pair united to prevent potential issues during future use. Like all pieces of the valvetrain, I prefer to keep the rocker arm assemblies in sequential order for inspection purposes.

Professional Mechanic Tip

Valvetrain Organizer

A valvetrain organizer, such as this from Comp Cams, is an excellent way to maintain the order of the valvetrain components for each cylinder during disassembly. It allows for complete inspection of each complementing component after the entire valvetrain has been removed. The high-quality plastic tray is impervious to oil and solvents and cleans up easily.

3 Remove Pushrods and Lifters

Remove the pushrods and organize them in sequential order. Then remove and organize the lifters in a similar fashion. Two hands are required for removal, so use one to push the lifter upward and the other to lift it from the bore. Quickly inspect each lifter face for immediate signs of abnormal wear, such as grooving, pitting, or cracking. Organize them in a manner so each lifter can be inspected closely along with its corresponding lobe when the camshaft is removed.

4 Remove Cylinder Head Bolts

The 10 bolts securing the cylinder heads were likely torqued in a specific pattern during assembly. It generally includes working in a spiral pattern outward from the center bolt. A spiral pattern is not necessary for bolt removal during disassembly. I tend to pick an outside bolt, unloosening each as I work toward the center in a spiral pattern. The head bolts are very tight. I use a long 1/2-inch-drive breaker bar for maximum leverage and I squarely seat a quality 3/4-inch socket against the cylinder head to prevent rounding the edges. Some bolts on this 400 required noticeably less effort to remove than others, which possibly indicates improper torque during install or a head gasket that didn’t crush evenly. I recommend loosely reinstalling one or two head bolts. It keeps the cylinder head from falling off the block during the next step.

Important!

5 Remove Cylinder Heads

Dowel pins locate the cylinder heads on the block. In most cases, you need to use a forceful upward tug to break the cylinder head free from any sealing compounds or corrosion. Place a pry bar into an intake port and smoothly apply pressure until the cylinder head pops up against the two remaining head bolts. If the cylinder head does not move after a fair amount of prying force has been applied, stop prying! Closely inspect for any hidden head bolts that may still be installed. Once the cylinder head is loose, remove the remaining head bolts and inventory them all, and lift the head up and away from the engine. I prefer grabbing the loose cylinder head near its exhaust ports and lifting it toward the center of the block, where I can carefully slide my fingers beneath and grasp it firmly. Fully assembled iron cylinder heads weigh nearly 60 pounds each, so be prepared. It can inflict damage and serious pain if dropped on your feet.

Critical Inspection

6 Inspect Cylinders

Visually inspect the pistons and cylinder walls to gain an insight on the engine’s overall operating condition. The dish found on these pistons reveals that the engine’s static compression ratio was much lower than its original rating of 10.25:1. The heavy deposits indicate that oil was entering the combustion chamber and that irregular combustion was occurring. The cylinder walls have a defined ridge at top but otherwise look fine.

Critical Inspection

7 Inspect Block and Head Gasket

Closely inspect the block deck and head gaskets for any signs of coolant and cylinder pressure seepage. If seepage is identified, there could be an underlying issue. If the head gaskets are in good condition, they can be reused if you’re on an extremely tight budget, but I strongly recommend using new, high-quality gaskets because a well-sealed head is essential. In this case, the coolant found leaking outward around this cylinder head bolt has clearly ruined this gasket. The leak was likely the result of an undertorqued head bolt, and we found several during cylinder head removal. Soot trails found between cylinders are further indication that the head bolts were not properly torqued.

Camshaft Removal

Special Tool

1 Remove Harmonic Balancer

Unbolt the water and fuel pumps, and remove the lower pulley from the harmonic balancer with 1/2-inch and 9/16-inch sockets. Inventory and set aside the hardware and accessories. You now have clear access to the harmonic balancer bolt, which should be extremely tight. I prefer a pneumatic impact wrench if compressed air is available. A very long 1/2-inch-drive breaker bar and a 15/16-inch socket can be used to remove the bolt, but crankshaft rotation must be prevented. Thread a long, hardened steel 1/2-inch x 20 stud into a flywheel bolt hole on the flywheel register. The stud locks the crankshaft when it contacts the engine stand so the balancer bolt can be removed.

Critical Inspection

2 Inspect the Harmonic Balancer

On a Pontiac V-8, the harmonic balancer is used to damp harmonic vibrations, and not necessarily balance the front end of the crankshaft as its name suggests. Pontiac actually corrected its name in later years, referring to it as a “harmonic damper” in factory literature. It is designed to be an integral part of the crankshaft, is located on the front snout by a large keyway, and is secured to the crankshaft by a bolt torqued to 160 ft-lbs. A common cause of harmonic balancer failure is improper bolt torque. That allows the balancer to shimmy on the keyway, which causes it to crack. If not caught quickly, it can cause the balancer to separate at speed or complete crankshaft failure. The harmonic balancer should be replaced if there is any sign of fatigue.

3 Remove Oil Pan

After the cylinder heads have been removed, an engine is much easier to rotate on an engine stand. Rotate the engine 180 degrees and remove the 18 bolts that secure the oil pan to the block and timing cover with a 7/16-inch socket. The oil pan should lift up and away, but it is usually bonded to the block with RTV sealer. Position a pry bar between the oil pan lip and the block rail. Apply gentle pressure and walk the pry bar around the pan until the oil pan is free.

4 Remove Timing Cover

Rotate the engine 180 degrees, returning it to right side up. Remove the two bolts and two nuts that secure the timing cover to the block with a 9/16-inch socket and inventory the parts. RTV sealer is often used to prevent leaks during rebuilds, and it was clearly used in this instance. Persuasion with a rubber mallet and pry bar is sometimes required to break the sealant’s bond on the timing cover.

5 Remove Timing Gear Set

Remove the fuel pump eccentric retaining bolt with a 3/4-inch socket, and then set it aside for later use. Walk the cam gear off of the camshaft snout with a pry bar. The crankshaft gear should slide off but could also require some gentle prying. Inspect the entire timing set for signs of abnormal wear, such as excessive chain stretch or worn gear teeth. None were found here.

6 Remove Camshaft

Remove the camshaft thrust plate with a 1/2-inch socket. Inventory the bolts and inspect the thrust plate for abnormal wear. If you don’t have a camshaft installation tool available, thread the fuel pump eccentric bolt back into the camshaft snout. It serves as something to grasp while pulling the camshaft outward from the engine. Position the camshaft far enough out so it can be firmly grabbed with one hand. The rear journal can be supported with the other hand and the cam guided through the bearings.

Critical Inspection, Documentation Required

7 Inspect Camshaft and Lifters