ATK GM 383 Stroker 500 HP HP55M Stage 2 Mid-Dress LB

Description

Broken valvetrain hardware and oil pump cavitation compromise track support haulers under hard pulls. The ATK GM 383 Stroker 500 HP HP55M Stage 2 Mid-Dress LB cures chronic power deficit through an aggressive commercial long block repower. This 6.3L 8-Cylinder assembly produces 500HP, though mechanics must verify electric fan shroud clearance against the forward water pump hub.

Constructed around an ASTM A48 Class 30 gray iron block, this ATK engine core incorporates ported A356-T6 aluminum heads and a 4340 forged steel crankshaft. Starter draw measures 175A at 12V. Bare weight equals 450 lbs within a compact base envelope measuring 28in length, 26in width, 27in height. Sump capacity holds 5.0 quarts oil inside the heavy-gauge steel pan.

Key Features of ATK HP55M

Service managers buy ATK GM 383 Stroker 500 HP HP55M Stage 2 Mid-Dress LB packages to slash engine bay rigging hours during industrial engine rebuild projects. The pre-installed intake manifold and circulating water pump align accessory belts without tedious shim adjustments.

• Bore diameter measures 4.030in paired with a 3.750in stroke for maximum stroker cylinder displacement.
• Mid-dress dressing supplies the dual-plane intake manifold, water pump, and aluminum valve covers.
• Aggressive hydraulic roller camshaft profile generates wide power curves without solid lifter maintenance.
• Forged 4340 steel H-beam connecting rods withstand high mechanical tension during downshift engine braking.
• HP55M commercial core balancing protocols isolate reciprocating vibration to protect drivetrain seals.
• Four-bolt cast iron main caps resist crankshaft cap walk under maximum cylinder combustion pressure.
• Full-floating piston pins reduce pin bore friction during protracted high-load operating periods.
• Fast-burn combustion chambers improve flame propagation to extract maximum force per fuel charge.

Hot Dynamometer Bench Specifications

Hot testing protocols measure parameters on each HP55M long block engine prior to transport. The stroker delivers 500HP at 5800 RPM and 480 ft-lbs torque at 4300 RPM. Crankshaft journal runout remains below 0.0003in TIR. Oil gallery pressure maintains 58 PSI hot at 190°F operating sump temperature. Dynamic cylinder compression registers 195 PSI across all cylinders with 3% variance. Exhaust gas temp stabilizes at 1340°F under maximum test cell brake load.

Bay Constraints Maintenance Schedule

Carburetor throttle linkage requires 6 lbs return spring pull force. This mid-dress competition package is NOT engineered for stock low-stall torque converters, computerized feedback carburetors, or vehicles operating on standard 87-octane pump gasoline.

• Replace initial break-in oil and spin-on filter after 500 road miles using high-zinc formula.
• Check hydraulic lifter preload cold, verifying one-half turn down from zero pushrod lash.
• Retorque aluminum intake manifold bolts to 30 ft-lbs following initial thermal cycles.

Commercial Warranty Freight Contents

Built according to the proven ATK assembly standard, this powertrain carries a 2-Year 24,000-mile limited warranty. The heavy wooden crate houses the dressed long block, aluminum intake manifold, water pump, valve covers, oil pan, and an official signed dyno test sheet.