What is the difference between @ 0.050\" and advertised cam timing?

@ 0.050\" timing is a common comparison standard for cam cards. Advertised timing is measured at a smaller lift point and typically appears larger. This calculator uses the same formulas either way; the toggle changes labeling.

Why is valve overlap important?

Overlap affects idle, vacuum, scavenging, and power curve shape. The best overlap depends on compression, exhaust, cylinder heads, and the intended use (street, strip, boost, nitrous, etc.).

ENGINE BUILD TOOL

Cam Timing Calculator (ICL, ECL, LSA, Duration & Overlap)

Q: What cam events do I need to use this calculator?

You need four events in crank degrees: intake opens BTDC, intake closes ABDC, exhaust opens BBDC, and exhaust closes ATDC (positive values).

Q: Does this replace degreeing a cam?

No. This tool helps interpret cam card events and compare profiles. Degreeing verifies the cam is installed where you intend, which is important for tight clearances or specific powerband targets.

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).

Fastime Performance Cam Timing Calculator

Enter signed valve events @ 0.050" (crankshaft degrees).

Negative values mean the opposite of each labeled direction. Use one checking lift, measurement location (tappet/cam or valve) and lash convention for all four events. Changing the basis does not convert the numbers between advertised and .050-inch timing; enter the matching cam-card events.

Presets are illustrative .050-inch event examples, not verified manufacturer cam cards. Loading a preset selects the .050-inch basis.

Events: @ 0.050" Advertised

Results (@ 0.050")

Intake Duration (° crank) 214.0°

Exhaust Duration (° crank) 232.0°

Event-midpoint ICL (° crank ATDC) 105.0°

Event-midpoint ECL (° crank BTDC) 110.0°

Event-derived LSA (° cam) 107.5°

Signed Overlap / Gap (° crank) 8.0°

Calculated from the entered @ 0.050" events; no checking-lift conversion is performed.

Using signed IO (BTDC), IC (ABDC), EO (BBDC), EC (ATDC):
Intake duration = 180 + IO + IC; exhaust duration = 180 + EO + EC.
ICL = intake duration ÷ 2 − IO (crank degrees ATDC).
ECL = exhaust duration ÷ 2 − EC (crank degrees BTDC).
Event-derived LSA = (ICL + ECL) ÷ 2 (camshaft degrees).
Signed overlap = IO + EC (crank degrees); a negative value means a gap at the checking lift.

Centerlines are event midpoints; asymmetric lobes may have different peak-lift centerlines. LSA is derived under this event model, not verified from the lobe profile. Use events around the same overlap TDC; this tool does not normalize multi-cycle degree readings or verify mechanical clearance.

Shop Timing Sets

Verify engine fitment, camshaft compatibility and any required advance or retard settings.

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 in signed crankshaft degrees (negative means opposite the stated direction):
- 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)

This tool derives ICL and ECL from the midpoint of each pair of valve events. For asymmetric lobes, these may differ from actual peak-lift centerlines; the derived LSA is an event-based estimate, not a measurement of the lobe profile. Follow the manufacturer’s cam card when degreeing a cam.

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

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.