Speed Pro R-9903 Engine Piston Ring Set

Speed Pro R-9903 Piston Ring Set

Speed Pro R-9903 is a standard-size engine piston ring set for 4.0000-inch bore applications. It combines a ductile iron plasma moly top ring, cast iron second ring, and standard-tension oil ring design for dependable sealing in compatible Ford, Chevrolet, Dodge, GMC, Mercury, and related V8 builds.

Built for Windsor and other listed applications, this ring set is a direct-fit choice for performance rebuilds and street engines where bore size, groove width, and ring face design must match the piston package.

Key Features

• Part number: R-9903
• 4.0000-inch bore diameter and outside diameter
• Top ring material: ductile iron plasma moly
• Top ring face design: torsional barrel face
• Second ring face design: reverse torsional
• Second ring material: cast iron
• Oil ring design: SS50U with standard tension
• Ring groove widths: 5/64 x 5/64 x 3/16 in.
• Standard size, non-file-fit design

Detailed Description

Speed Pro R-9903 is engineered for 4.0000-inch bore engines that use 5/64-inch top and second ring grooves with a 3/16-inch oil ring groove. The plasma moly top ring helps provide a durable sealing surface, while the reverse torsional second ring and SS50U oil ring design support consistent cylinder sealing and oil control in rebuilt engines. This part cross-references Eastern Catalytic 40882 for the same application.

Compatible With 1962-1997 Ford F-150, F-250, F-350, Bronco, E-Series vans, LTD, Mustang, Thunderbird, Lincoln Continental, Mark VI, Mark VII, Town Car, Mercury Grand Marquis, Capri, Cougar, Marquis, and Versailles applications listed in the fitment data. It also covers selected Chevrolet Camaro, Corvette, Impala, Malibu, Nova, El Camino, Blazer, Monte Carlo, and GMC truck and van applications, plus listed Dodge, Chrysler, Plymouth, Buick, Oldsmobile, and Pontiac models.

What It Helps Solve

• Low compression from worn or damaged piston rings
• Excessive oil consumption caused by poor ring sealing
• Blow-by and crankcase pressure issues
• Loss of cylinder sealing after an engine rebuild
• Mismatch between piston groove widths and ring set dimensions

Installation Notes and Tips

• Verify 4.0000-inch bore size before ordering.
• Confirm piston groove widths are 5/64 x 5/64 x 3/16 in.
• Use with the listed H653P piston applications where specified in fitment notes.
• Check cylinder wall condition, ring end gaps, and ring orientation during assembly.
• Follow the engine builder’s break-in and lubrication procedures for plasma moly rings.

Quality Assurance

Speed Pro states that its HP engine components are built to deliver value and quality for track, strip, and street use. R-9903 is a standard-size piston ring set made to meet the dimensional requirements shown in the product data for the listed applications.