Q: I’m building a 440 for a Ramcharger. The engine will have to pull about 9,000 pounds GCW so I want a lot of low to midrange power. The engine is bored .040 inches over, will have 9.3:1 to 9.5:1 compression ratio, and has mildly ported open chamber heads with 2.08 inch intake/1.74 inch exhaust valves. The intake is a Weiand Action-Plus dual plane. The exhaust manifolds are from a 440 6-Pack engine with 2 1/4 inch outlets. The rear axle gear ratio is 3.55:1 with 255/70R-15 tires.
My question is: Which camshaft will give the best low to mid-range torque – an even duration or a split-duration? Without changing duration, would increasing lift have any effect on the torque curve? What’s the maximum duration I could use without getting a rough idle?
A: A split duration cam would be best for low and midrange power. Increasing lift may help airflow if the heads are capable of flowing more, but this would have an adverse effect on low-end torque for towing. A camshaft duration of 214 to 218 degrees (intake) at .050 inch lift and a 110-degree centerline would be the maximum for your application. Comp Cams has a good hydraulic cam for you, part number CCA-21-404-4. It features 214/229 degrees duration at .050 lift, and .442/.482 inches of lift with a 110 degree lobe center. This is a single-bolt cam.
We have assembled several camshaft guides to help with your cam questions:
- The 9 Things You Should Know Before Ordering a Camshaft
- 8 Causes of Camshaft Failure and How To Prevent Them
- Camshaft FAQs: What is Lobe Separation? What are Intake and Exhaust Centerlines? (And More)
- Evaluating Various Camshaft Styles
- Understanding Camshaft Specifications
- The 5 Key Camshaft Specs You Need to Know
- How to Degree Your Camshaft
- A Glossary of Camshaft and Valvetrain Terms