DJ Rock PR420 Engine Piston Ring Set

Engine piston ring set for service rebuilds

DJ Rock PR420 is a premium engine piston ring set built to restore sealing between the piston and cylinder wall. It is specified for complete engine service applications and uses a 1.5 mm top ring configuration with an 84.8 mm bore diameter.

Fits 2000-2004 Ford Focus, N/A. Fits 1997-2002 Ford Escort, N/A. Fits 1997-1999 Mercury Tracer, N/A. Part number PR420 is also cross-referenced to Hastings Piston Rings 2M4889 for the same application.

Key features

• Premium-grade piston ring set for internal engine service
• 84.8 mm bore diameter for the listed applications
• 1.5 mm top ring specification with matching ring stack design
• Compression, wiper, and oil control ring layout for sealing and oil regulation
• Manufactured from cast iron or steel alloy materials with surface treatments for reduced friction and wear resistance

Detailed description

PR420 is engineered to maintain compression, control oil consumption, and support heat transfer across the cylinder wall. The ring set is manufactured to OEM quality standards and uses durable materials and surface finishes such as chrome plating, molybdenum coating, or nitriding to improve sealing performance under demanding engine conditions. For Ford Focus, Ford Escort, and Mercury Tracer engine rebuild work, PR420 provides the ring package needed for complete cylinder service.

What it is used for

• Low compression caused by worn piston rings
• Excessive oil consumption from poor ring sealing
• Blow-by from reduced cylinder sealing
• Uneven cylinder performance during engine rebuilds
• Restoring ring function during complete engine service

Installation notes and tips

Verify bore diameter and ring configuration before installation. Match the ring set to the engine’s cylinder dimensions and service specifications, and inspect cylinder walls for wear or taper before assembly. Proper ring end gap measurement and clean installation practices are important for sealing performance.

Quality assurance

DNJ Engine Piston Ring Sets are manufactured to meet or exceed OEM quality standards. PR420 is built with premium materials and precision engineering for consistent service life in rebuild applications.