85mm Tapered Ring Compressor

The ARP 85mm Tapered Ring Compressor is an essential engine building tool designed for engine machinists, rebuilders, and serious DIY enthusiasts working with 85mm bore engines. This precision instrument compresses piston rings during engine assembly, protecting ring ends from damage and ensuring correct seating during cylinder head installation. Proper ring compression prevents costly installation errors and extends engine longevity by maintaining ring integrity throughout the break-in process.

Manufactured from black anodized aluminum, the 85mm tapered ring compressor delivers reliable performance while resisting corrosion and wear in the workshop environment. The tapered design allows smooth, controlled compression of piston rings without binding or uneven pressure distribution—critical for rings with varying thicknesses and spring tensions. ARP's precision engineering ensures the compressor slides easily over the piston and into the cylinder bore, accommodating the 85.00mm bore specification with tight tolerances that prevent ring escape during installation.

This compressor is ideal for builders tackling small-block and mid-displacement engines common in performance, marine, and light industrial applications. Weighing just 0.69 lbs and measuring 5.5 x 2.5 x 5.5 inches, it stores compactly in any toolbox and is portable for field engine work. Whether performing a full rebuild, replacing a single piston, or assembling a newly bored engine block, the ARP 85mm tapered ring compressor is the trusted standard for preventing ring damage and ensuring professional-quality assembly results.