ENGINE BUILD TOOL
Cam Timing Calculator (ICL, ECL, LSA, Duration & Overlap)
Use this cam timing calculator to convert valve events into the numbers builders actually use: intake duration, exhaust duration, intake centerline (ICL), exhaust centerline (ECL), lobe separation angle (LSA), and valve overlap. Enter events either @ 0.050" or advertised (crank degrees).
How to Use This Cam Timing Calculator
- Choose event type: @ 0.050" or Advertised (labels only — math is the same).
- Enter the four valve events (positive values only):
- Intake opens BTDC and intake closes ABDC
- Exhaust opens BBDC and exhaust closes ATDC
- Click Calculate Cam Timing to see duration, centerlines, LSA, and overlap.
If you’re selecting a cam for your combo (not just crunching numbers), start here: Choosing the Right Camshaft for Your Build and Camshaft Types Explained. :contentReference[oaicite:1]{index=1}
What These Cam Numbers Mean
Duration
Duration is how long the valve is open in crank degrees. More duration generally shifts power higher in RPM, but affects idle quality, vacuum, and street manners.
Centerlines (ICL & ECL)
Centerlines help you understand where peak lift occurs relative to TDC. Builders use these to verify installed cam timing, degree a cam, or compare profiles when looking at cam cards.
LSA & Overlap
LSA and overlap influence idle, vacuum, scavenging, and power curve shape. They also affect how a combo behaves with boost, nitrous, or higher compression.
For overall combo matching (cam, heads, compression, fuel, and intended use), read: How to Match Engine Parts for Your Application. :contentReference[oaicite:2]{index=2}
Related Build Guides & Parts
Helpful Guides
- Choosing the Right Camshaft for Your Build
- Camshaft Types Explained
- How to Match Engine Parts for Your Application
- Compression Ratio Calculator
- Fastime Performance FAQ
Tip: use this tool to understand cam cards, then verify installed timing during assembly if you’re chasing a tight window (boosted combos, nitrous, tight piston-to-valve, etc.).
Shop Cam & Valvetrain Parts
- Shop Camshafts :contentReference[oaicite:3]{index=3}
- Shop COMP Cams :contentReference[oaicite:4]{index=4}
- Shop Lunati :contentReference[oaicite:5]{index=5}
Need help choosing the right cam?
Tell us your build goals, vehicle, gear/converter, compression, and head specs — and we’ll point you toward a cam that works. Contact Fastime Performance.
Cam Timing Calculator FAQ
What’s the difference between @ 0.050" and advertised timing?
@ 0.050" is a common “apples-to-apples” comparison point for cam cards. Advertised timing is measured at a smaller lift point and usually looks bigger. This calculator runs the same math either way — the toggle changes labeling.
What do I do if my cam card shows different terms?
Convert to the four events used here: intake opens BTDC, intake closes ABDC, exhaust opens BBDC, exhaust closes ATDC. If you have those, this tool will output duration, centerlines, LSA, and overlap.
Does this calculator replace degreeing a cam?
No — it helps you interpret valve events and compare profiles. Degreeing verifies the cam is installed where you intend, especially when chasing tight clearances or a specific powerband.
Why is overlap important?
Overlap influences idle quality, vacuum, scavenging, and how the engine behaves with compression, exhaust, and induction. The “right” overlap depends on the application.
Fastime Performance Cam Timing Calculator
Enter valve events @ 0.050" (crank degrees). Positive values only.
Results @ 0.050"
Inputs and results shown as @ 0.050".
Formulas (crank degrees):
Duration = Open + 180 + Close
ICL = (Intake Open BTDC + Intake Close ABDC + 180) ÷ 2
ECL = (Exhaust Open BBDC + Exhaust Close ATDC + 180) ÷ 2
LSA = (ICL + ECL) ÷ 2
Overlap = Intake Opens BTDC + Exhaust Closes ATDC
