Sage-Tips

What makes a cam have a choppy idle?

The reason race cars have that rough idle is because the engines used are designed for high-rpm operation. The reason you want to stay away from an increase in lobe lift is because of the changes youll need to make to a stock engine if the cam has more than approximately .

How does cam duration affect idle?

Again, keeping all else constant, more duration will make the engine less efficient at low rpm, with more overlap dilution of the induction charge, and the later intake valve closing reducing the trapping efficiency. Therefore, a long-duration cam will cause rough running at idle (lope) and a loss of low-rpm torque.

What do upgraded camshafts do?

Upgrading the factory camshaft is a great way to gain more power and torque. It’s usually the next step after improving exhaust and the cold air intake. ​Chromoly pushrods give drivetrain stability and don’t induce valve float at high rpm like the factory pushrods would.

Is camming a car bad?

Yes. Adjusting the camshafts so the cams are slightly ahead or behind will alter the engine’s performance. Advancing the timing will cause the fuel intakes to open and close earlier, which improves low-end torque. Conversely, retarding the cam will improve high-end horsepower at the expense of low-end torque.

How does cam lift affect performance?

Designing a cam profile with more lift results in increased duration in the high-lift regions where cylinder heads flow the most air. Short duration cams with relatively high valve lift can provide excellent responsiveness, great torque, and good power. But high lift cams are less dependable.

What makes a lumpy idle?

Causes of a rough idle. Many different problems could result in a rough idle for your car or truck, including: dirty fuel injectors, clogged air filters, bad spark plugs, and a variety of exhaust system issues.

What makes an engine choppy?

An acceleration problem is usually the result of insufficient fuel, air, or spark during the combustion process. Worn-out spark plugs or the electrical cables attached to them are one of the most common causes of cars stuttering.

Do aftermarket camshafts increase horsepower?

Maxing Engine Performance. Consider installing a performance camshaft. Performance cams increase the duration and timing of the valve openings during the engine stroke, increasing horsepower and making your car accelerate more quickly.

What’s more important cam lift or duration?

Designing a cam profile with more lift results in increased duration in the high-lift regions where cylinder heads flow the most air. Short duration cams with relatively high valve lift can provide excellent responsiveness, great torque, and good power.

What happens if you put a 400cc Cam in a 302?

A 302-cu.in. engine will behave differently than a 400-cu.in. engine with the same camshaft. The larger the displacement, the less impact aggressive valve timing will have, so a cam that makes that 302 choppy at idle and a screamer in the upper rpm range will seem tamer in that 400.

Is bigger really better when it comes to camshafts?

Not so long ago, the bigger is better philosophy reigned supreme regarding camshafts. The result was overcammed engines that sounded great and could crank serious top-end power, but were not very streetable and couldn’t idle to save their lives.

What makes a high performance Cam with a long duration?

Thus, a high performance cam with long duration should ideally be combined with a higher static compression ratio. That way the engine can benefit at high RPM from the maximized amount of intake charge afforded by the late intake valve closing, and still achieve sufficient compression of the mixture as a by-product of the dynamic compression ratio.

What happens if you run a cam at too high RPM?

This will lead to excessive compression losses, detonation and could even lead to head gasket or piston failure. On the other hand, an aggressive cam with a late intake valve closing point will work well at high RPM.