Last month we showed you guys how to machine and properly build a 383 small-block bottom end. We used a Lunati 383 stroker kit with 6.0 rods, -4.9cc flat-top pistons, and performed the machine work at Pfaff Engines. The bottom end was installed and parts were on order for the top end. We decided to use slightly larger heads for our test engine from 180cc to 195cc from Airflow Research (AFR) to increase the upper rpm horsepower while maintaining great lower end torque.
To help control the oil we installed a Moroso oil pan and pump that has oil traps when under hard acceleration, braking, and cornering. The Comp Cams cam was quite unique because it featured a four-grind pattern that helped the intake and exhaust flow better by increasing the duration and lift on the outer cylinders 1, 2, 7, and 8. Comp Cams also increased the exhaust lift and duration on the exhaust side 1, 2, 7, and 8 to promote increased exhaust flow. The cam grind we chose for our 383 build was measured at duration @ .050 230/240, valve lift .620/.608 with 1.6 rockers on a 110.5 lobe separation angle. For the inner cylinders (3, 4, 5, 6) duration @ .050 228/238, valve lift .617/.605, and 109.5 LSA.
One important thing is that the Lunati 383 stroker with the longer H-beam rods needs to have a small base circle cam so that the rods don't hit the cam. The Comp Cams Pro Magnum 1.6 full roller rockers work great to free up engine friction and are very strong and lightweight. Comp claims the rocker arms actually weigh 5 percent less at the valve than comparable aluminum rockers. With a lighter valvetrain, (rockers, titanium spring retainers, valves, etc.) the engine can spin up faster and usually have a higher rpm range, thus making more power.
The intake we chose for testing was a new Edelbrock 7501 RPM Air-Gap for great performance from 1,500-6,500 rpm. This intake is a great choice for truck guys because the Air-Gap separates the oil from the lifter valley area from hitting the bottom of the intake, heating up the intake charge. The cooler intake charge means the engine usually increases performance. We chose to reinstall our F.A.S.T. fuel injection for two reasons: one, it works great to control fuel when driving normally or racing, and two, it self learns. How can we go wrong?
Now it's time to put it all together and walk you through the steps we took to make sure the 383 ran its best.