How to Rebuild Pontiac V-8s - Updated Edition. Rocky Rotella
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 |
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| 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 |