Just like all hobbies, racing takes the right tools. And your ‘tool’ is an automobile with the precise combination of the right combination of components. But just like all machines, yours could always go a little faster, run a little smoother and win you a few more trophies.
Right down to the tires, you could build the ultimate automobile. Once your have it firing on all 12 cylinders, picking the right cam for your stock car is crucial. Dependent on plenty of factors, in a game of inches the right cam could be the difference between clutching the checkered flag and going home empty-handed.
A few pointers to keep in mind when picking out the right cam:
1. The best cam is typically NOT the one in the car when they get the chassis sorted out. This is in great part because aftermarket, short-duration cams with wider lobe separations usually yield much flatter torque curves. But longer rod motors prefer a shorter duration cam with wider lobe separation while longer duration cams require tighter lobe separation to have any power off the corner. Finding the balance right for your ride performance is what makes you the expert.
2. Stock exhaust manifolds or a highly restricted exhaust usually respond well to shorter exhaust duration and wider lobe separation. Power increases are most evident at higher rpm where exhaust backpressure is greatest and reversion is most prevalent.
3. Most unported heads approach 85 or 95 % of peak flow at .400 to .450 lift and do not need or want a maximum valve lift over .540 to.555. Often a low cam lift with 1.65 or 1.7 ratio rockers is very helpful on the intake side as long as lift is kept to about .550. Exhaust is less critical with 1.5 or 1.55 being the most popular.
4. Glowing exhaust pipes may be an indication of over scavenging by the exhaust. Smaller headers, or even a restrictor plate at the header may help. The problem is often mixture burning in the exhaust rather than in the cylinder. Be sure to ascertain which problem you have as the lean mixture is a much more serious problem and can cause quick meltdown.