This outer valve spring (part number 198216700) is designed for 3-cylinder Perkins 403C-15, 403D-15, 403D-15T and 4-cylinder 404C-22, 404C-22T, 404D-22TA diesel engines (2.2 L capacity). It maintains correct valve motion at speeds up to 3,000 min⁻¹ in engines powering JCB 3CX compact back-hoes, 45 kVA "Vista A" generator sets, MF 1700 tractors, and mini-excavators.

Constructed from chrome-vanadium spring steel (50CrV4 alloy with 0.5% C, 1% Cr, 0.15% V), this valve spring offers exceptional durability with 1,600 MPa tensile strength and 8% elongation. The material resists surge-set when exhaust temperatures reach 700°C. Controlled shot-peening at 0.25 mm A-intensity induces 400 MPa compressive stress on the outer surface, delaying fatigue crack initiation and extending service life to 12,000 hours with fatigue life rated at 10⁷ cycles.