Compression is important, but dont make the mistake of going too far. One point in compression is generally worth between 3 and 4 percent increase in horsepower. On a 400hp engine, a 4 percent increase is 16 hp. Piston design, combustion chamber size, deck height, and head gasket thickness all affect compression.
There are several carburetors that can do the performance job. The 750-cfm Q-jet (right) is excellent for daily-driven engines, while a vacuum secondary Holley 750-cfm carb (middle) is a universal favorite. The Barry Grant Demon series carbs (left) are also excellent.
There are two basic types of street intake manifolds. On the engine is a single-plane intake that is identified by its open plenum area. The dual plane (above) is easily spotted by its divided plenum. The dual planes offer more torque and driveability while the single-plane intakes generally make more peak horsepower.
Even if youre running stock iron heads, dont overlook the valve job and valves as a source of power. An inexpensive pocket porting job and quality valves can pump the horsepower an easy 25 to 40 hp if done properly.
You cant make decent power without a performance exhaust system. A set of headers, a 21/2-inch dual exhaust system, and a pair of quality mufflers will go a long way toward ensuring decent power from your engine. Exhaust systems dont make power, but they allow the engine to make all it can.
One of the best performance-per-dollar investments is the right camshaft for your application. Flat-tappet hydraulic performance camshafts have never been better than they are right now, and you can buy a cam and lifter kit for well under $200.
Roller cams are becoming increasingly popular with the street set. Hydraulic rollers can make great power, but suffer from heavy lifters so they cant rpm like a solid roller. The biggest drawback is the price. A complete roller cam, lifter, pushrod, roller rocker arm, and valvespring kit can set you back around $1,000 but the parts make great power.
Ignition systems are important with any engine. The most popular pieces are the capacitive discharge (CD) systems like the MSD 6A, Crane HI-6, and the Jacobs FC-1000. For mild street engines at 450 hp or less, these systems arent required.
With higher engine speeds, a quality rocker arm is almost a necessity. Stock rockers are overly stressed when teamed with high spring pressures. The best choice is a full roller rocker arm like the Crane (middle left) or the Comp Cams Hi-Tech stainless rocker (far left).
An alternative to the big-bore 502ci Rat is to go with a stroker crank with a stock 454 block bored 0.060-over to come up with a 496ci displacement. This is a Scat steel crank and rod package.
Its always a good idea to degree the cam when assembling the engine. This way you know where the cam is installed.