When stroker engine kits first came out onto the scene, they were considered to be reserved only for the big-buck racers. The kits were expensive, as very few machinists were capable of producing them, and the labor involved appeared intense. As a result, stroker kits were unpopular compared to major bolt-ons such as superchargers and nitrous.
However, as aftermarket companies began to offer stroker kits at more affordable prices, the idea of tossing in a big-armed crankshaft seemed more feasible. No longer were stroker kits considered a luxury. Instead, they became so mainstream that most street enthusiasts today are out there running them in addition to their favorite power adder.
But with the desire to add cubic inches comes the need to address other issues. As the displacement increases, the engine moves more air, fuel and exhaust like never before, and does so at lower engine speeds. It also has more aggressive torque and horsepower characteristics. Therefore, it is imperative that you pay attention to the details to make sure that your next stroker installation is taken to the fullest. After all, what good would the addition of cubes be if its power-making potential was lost due to inadequate support systems?
When you purchase a stroker kit, make sure you ask the merchant or engine machine shop what the rotating assembly is balanced to. There is usually one of three responses you'll hear. Most 315/331/347 stroker kits for the 302 reuse your existing 50-ounce imbalance flywheel/flexplate and corresponding harmonic damper. The other popular OEM Ford imbalance is 28 ounces and is often found on most 351-based stroker kits. The 28 ounce imbalance is the better of the two because it requires less offset weight to be placed on the far ends of the crankshaft. Generally, the heavier the weight of imbalance, the more weight the crankshaft has to swing around to spin smoothly.
The last type of rotating imbalance, and by far, the most desirable, is called zero balanced. That means all of the weight that needs to be removed or added to balance the rotating crankshaft is located on the crankshaft itself. It not only makes for a stronger crank, but it allows for high-rpm operation. Unfortunately, it comes at a high price, typically adding $500-$1000 to modify an existing crank, or up to $3,000 for a billet crank that is designed from the ground up as zero-balanced. Whichever setup you use, make sure you acquire the correct flywheel and damper. Another thing to look for is proper tooth count on the flywheel or flexplate. It will be either 157 or 164 teeth.
Induction
The stock 5.0 intake manifold is much better than most think. Although it can work well on mild 302s, once the cubes are upped to 315 and above, the need for a larger intake manifold is required. The term "larger" is mainly in reference to the crossectional area of the intake runners, and the manifold's plenum volume. Both play major roles in how well the heads and bores accept the intake air charge and will dictate whether your engine will be a dud or a stud.
Generally, with a modest bump in displacement, you'd want to jump to a larger intake almost immediately. There are a lot out there to choose from, but don't let your wallet dictate what goes on top. The most important thing to have is a matched combination. If you want to build a good street motor, consider one of the long-runner intakes. The most popular one out there is ,without a doubt, the Cobra upper and lower. Closely based on the GT-40 intake setup, it offers a great compromise in price, adequate runner crossectional area, and plenum volume. This has been the intake of choice for those who keep their engine speeds at or around 5500 rpm with up to 347 cubic inches. Other excellent long-runner manifolds include the Holley SysteMax II, the TFS Track Heat, and the Edelbrock Performer and Performer RPM manifolds. All work well, and are priced relatively close to each other. For the ultimate in streetable torque and great high-end horsepower, get any of these intakes Extrude-Hone ported or hand ported and polished for best results.