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Camshafts are long metal rods with various ovals of shaped metal (called lobes) that control the opening and closing of engine valves. The valves are precisely timed to open and close based upon combustion within the engine cylinder. Manufacturers tend to create mild camshafts that produce smooth even idle, and help an engine produce a broad range of power. You can alter the camshaft timing by replacing the factory camshafts with aftermarket units, which is a popular upgrade option particularly among V8 owners.

Camshaft Location

The camshaft will be located in different places based upon the design of the V8. In a pushrod V8 one camshaft is buried in the center of the engine block. Metal rods (called pushrods) used in conjunction with rocker arms connect the camshaft to valves. In a overhead camshaft V8 (OHC), either a single (SOHC) or dual (DOHC) camshafts sitting above the engine banks. Lifters and springs are used to actuate the valves. A SOHC may have rocker arms since only one camshaft operates both banks of cylinders.

Camshaft Operation

The camshaft rotates based upon a chain that runs from the crankshaft. As the camshaft spins, the lobes on the camshaft cause the valves to open and close. Manufacturers create camshafts with mild timing that insures the intake and exhaust valves are not open at the same time -- called overlap. While earlier V8s employed fixed timing, todays modern engine management systems allow for variable timing, where the valve timing is changed by moving the camshaft to adjust for engine speed, which in effect advances or retards the valve timing.

Performance Improvement

Large performance gains can be obtained with a aftermarket or altered factory camshaft that advances timing. When an engines intake and exhaust subsystems are altered, this changes the airflow of the engine, and thus a revised camshaft can optimize valve operation. In addition, by allowing for some overlap (where both the intake and exhaust valves are open at the same time), the engines performance is increased at the expense of poor and choppy idle (which is a plus to most V8 enthusiasts).

Tuning

To optimize camshaft performance, you must have the vehicle tuned after installation. While the camshaft controls timing of valves, the fuel and spark (injectors and coils) will need to be adjusted to match the revised airflow.

Before you mount a Twin Cam engine on an Evoluation (Evo) hard tail, you must take into consideration the two types of Twin Cam engines. The Twin Cam 88B is balanced, and although it is theoretically possible to modify an Evo frame to accommodate a Twin Cam 88B, it is probably not worth the trouble. The Twin Cam 88A is not balanced and it is possible to mount this engine in an Evolution frame. It is irrelevant whether the frame is a bolt-on hard tail, weld-on hard tail, softail or swingarm frame. Zodiac Performance Products and Vulcan Engineering both sell motor mount adapter plates that are intended to facilitate the installation of a Twin Cam 88A in an Evo frame.

Instructions

1

Bolt the Zodiac adapter plate to the rear engine mount with a hex socket and socket wrench. Grind the frame mount flush with the front of the adapter plate if any part of the rear engine mount protrudes in front of the adapter plate using an angle grinder.

2

Bolt the adapter plate to the engine with a hex socket and socket wrench. Mark the 3/8-inch wide cast gusset that is visible through the right side adapter plate window with a mechanics awl.

3

Unbolt the adapter plate from the engine. Grind the marked area of the gusset flush with the engine case casting to create spanner clearance.

4

Place, but do not bolt, the adapter plate on the rear engine mount. Align the two dowels included with the adapter plate in the engine bottom flange.

5

Slide the engine into the frame. Lift the back of the engine onto the adapter plate.

6

Bolt the adapter plate to the engine with the 3/8 by 2-inch Allen screws and washers included with the adapter plate using an Allen socket and socket wrench.

7

Bolt the adapter plate to the rear motor mount with the 3/8 by 1 3/4-inch Allen screws and washers included with the adapter using a Allen socket and socket wrench.

8

Wrench tighten the rear engine mount and adapter bolts to 38 foot-pounds of torque with an Allen socket and torque wrench after installing the stock, front engine mount.