Atomic 475 ST Barra Rebuild Kits
Engineering Overview
SPEC-DOC
Atomic 475 Rebuild Kit
The Smart Step-Up
The Atomic 475 Rebuild Kit is the perfect starting point for any performance-minded enthusiast seeking to build a robust and reliable Barra engine without breaking the bank. Engineered as a significant step up from a standard rebuild, this kit provides a rock-solid OEM+ foundation that easily handles moderate boost increases while maintaining factory-like street manners.
Cast doesn't mean weak. By pairing our zero-failure Superleggera Billet Rods with premium Hypatec Cast Pistons, you get a dead-quiet cold start and excellent oil control, while the billet rods absorb the immense torque spikes generated by modern turbochargers. It is the ultimate balance of daily drivability and weekend track capability.
A Complete System
We don't leave your oiling and sealing to chance. The 475 Kit includes our Rebuilt Alloy Oil Pump featuring Billet Gears, ensuring your oil pressure remains stable under load. We also lock down the cylinder head with our 12mm Tool Steel head studs and an MLS-D head gasket, eliminating the risk of head lift at elevated boost levels.
Kit Highlights
Rotating Assembly
Hypatec Cast Pistons paired with Atomic Superleggera Billet Rods (CA625 Bolts). Includes ACL Race Series bearings.
Oiling & Timing
Rebuilt Alloy Oil Pump with Billet Gears and Backing Plate. Supplied with our HD Timing Chain Kit.
Top End Sealing
Held down by 12mm Tool Steel Head Studs and sealed with our ultra-tough MLS-D Head Gasket.
Valvetrain Control
Includes Stage 2 Valve Springs (80-90 lbs) and HD retainers to prevent valve float under increased boost.
⚠️ The Minimal Machining Advantage
This kit is explicitly engineered to save you thousands at the machine shop. By meticulously matching components, we've eliminated the need for heavy block and head modifications.
- Save ~$500 on Block Prep: Assuming a healthy starting bore, use the standard size (92.3mm) Hypatec pistons to skip the expensive boring process. The block only needs to be honed and decked.
- Plug & Play Cylinder Head: The head requires a standard service only—seat the new valves (will require slight seat grind), install new seals, and vacuum test. No new valve seats or guides are required. Our 12mm Tool Steel studs drop straight in with no block re-threading.
- No Main Tunnel Machining: Because this kit utilizes the factory main caps without a heavy girdle, there is absolutely no need for line-honing the main tunnel, saving you significant machining costs.
- Ready-to-Run Internals: The oil pump is supplied rebuilt and ready to bolt on. Conrods are final sized, with pin clearances pre-set to 0.0005", and rarely require honing to suit a good condition crank with ACL standard bearings.
Choose Your Rebuild Phase
Available in three distinct configurations depending on your build requirements.
Phase 1
The core components required to strengthen your bottom end.
- 6x Hypatec Cast Pistons (12cc Dish)
- Hastings Piston Rings
- Heavy Duty Wrist Pins
- 6x Superleggera Billet Steel Rods
- CA625 Conrod Bolts
- ACL Race Main Bearings
- ACL Race Conrod Bearings
Phase 2
Adds essential oiling, timing, and head sealing components.
- Includes all Phase 1 items
- Rebuilt Alloy Oil Pump w/ Billet Gears
- 12mm H13 Tool Steel Head Studs
- MLS-D Extreme Duty Head Gasket
- -P Timing Chain Kit - HD Chain, Billet curved guide and pivot, OE top guide and fixed guide
Phase 3
The complete package, adding a valvetrain safety overhaul.
- Includes all Phase 1 & Phase 2 items
- Atomic Stage 2 Valve Springs (80-90 lbs)
- New Valve Stem Seals
Optional Upgrades
| Upgrade Component | Benefit & Application |
|---|---|
| ICON Forged Pistons | Upgrade from Cast to Forged (Step up to 550 Spec). Essential if planning to push beyond 650hp or use aggressive launch control, RPM limiters, 2-step. |
| Full Steel Oil Pump | Replace the rebuilt alloy housing with our Race Spec full steel housing for zero thermal expansion pressure loss. |
| 10mm Billet Main Girdle | Tie the main caps together to prevent cap walk under increased boost and RPM (Note: no machining required). |
| ATI Super Damper | Protect your new oil pump gears and bearings from destructive crank harmonics. |
