Atomic - 475 ST Barra Rebuild Kits

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.

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.

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 (STD)
ACL Race Conrod Bearings (STD)

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

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.

Bottom End Gaskets | Seals

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Atomic - 475 ST Barra Rebuild Kits