Understanding Timing Wheels

These charts provide a circular view of the valve events relative to the crankshaft rotation:

• 0° (Top / 12 o'clock): Top Dead Center (TDC).
• 180° (Bottom / 6 o'clock): Bottom Dead Center (BDC).
• Blue Arc: Intake Valve Duration.
• Red Arc: Exhaust Valve Duration.
• Overlap: Look at the 12 o'clock position.
  • If the Red and Blue bars cross each other, you have Positive Overlap (e.g., Cam 306552).
  • If there is a gap between them, you have Negative Overlap (e.g., Cam 306550).

LSA & Performance

• 112° LSA: The gap at the top closes and eventually overlaps as you move from the mild 306550 to the aggressive 306552 st5+.
• 114° LSA: Widening the LSA shifts the Intake (Blue) slightly clockwise (opening later) and the Exhaust (Red) slightly counter-clockwise (opening earlier), reducing the overlap potential.
• 116° LSA: This setting shows the largest gaps at the 12 o'clock position (least overlap), which correlates to the smoothest idle and highest vacuum.

Key Features

• Suits all Ford Barra DOHC 4.0L 6-cylinder engines (BA–FGX)
• Stage 1 to Stage 5+ profiles available for street, strip, and race
• Designed to enhance breathing and reduce required boost
• “Duo Phased” inlet lobes introduce swirl for better cylinder fill & efficiency
• Inverted flank asymmetrical lobes – rapid valve lift without excessive lift height
• Slightly reduced base circle for improved lifter preload control
• Compatible with VCT and standalone ECUs (VCT-delete optional)
• Developed and tested in-house since 2006 — proven track record
• Used in builds producing 570–1133RWKW

Why Choose Atomic Cams?

We engineer our cams to work as part of a complete system.

• Production: Made by Crow Cams to our specs. 
• Efficiency: Optimised profiles and split intake lobes increase efficiency and power
• Cylinder Fill: Increase cylinder filling efficiency with better valve timing events due to increased swirl from intake phasing
• Idle Control: Maintain idle vacuum with ability to tough idle (Stage 3 & 4); aggressive idle and reduced idle vacuum (4Plus & 5Plus).
• Power: Gain more power at lower boost by improving efficiency and reducing losses and back pressure
• Stability: Designed to retain valvetrain stability at high RPM due to Crow Cams R&D and lobe optimisation.
• System Match: Pair perfectly with Atomic HD valve springs, HD Roller rockers & Anti-pump lifters.

🔧 Installation Guide

1. Remove turbo ducting and rocker cover.
2. Align timing marks by rotating the engine until TDC shows timing marks aligned, remove VCT units, mark and remove cams.
3. Install cam gears/sprockets on camshafts and install camshafts in head and set timing chain in correct position.
4. Check lifter preload, rocker roller wear, and spring tension. 
5. reset tensioner (do not manually force it out) and confirm timing mark alignment.
6. Rotate engine manually to verify timing. We recommend confirming piston to valve clearance with plasticene. 
7. Start engine and idle at 1500-2000 RPM for 10 minutes.
8. Hydraulic lifters may take up to 45 minutes to fully bleed and may require one or two starts.

🛠️ Torque & Setup

• Ensure all bolts torqued to OEM specs.
• Tuning for CAMS required after installation for best results.
• Camshafts do not require a run-in period but benefit from high zinc oil.