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