Our products will give long and reliable service once correctly selected and fitted, however as with all things mechanical , the eventual need for maintenance and repair cannot be overlooked. We are the only manufacturers of roller rockers who offer a repair service and a range of service parts.
To order parts, first establish rocker number's name and size of components required. If you cannot identify the part no required, quote rocker number then part name and quantity required. All rocker numbers are stamped on the arm and have a manufacturers code in the inner tip.
Yella Terra Heat treated locks are formed from alloy steel and heat treated to improve strength and load carrying capacity and resist "fretting" in service. Recommended for applications where ultra high spring pressures are not used and valve float is not experienced or kept to a minimum.
The finest quality alloy steel is chosen for these precision-machined posilock nuts. Heat-treated, blackened and fitted with set screw, they can be relied upon to give excellent service. They are superior in strength and toughness to many other brands they are interchangeable with. Use with hydraulic or solid lifter cams.
Yella Terra Valve stem lash caps with oil hole are machined from alloy steel, heat treated and ground. They can be used to "fine tune" rocker arm geometry and stop mushrooming of soft titanium or stainless steel valve stems tips. May also be used to salvage valves with damaged stems.
Yella Terra Heavy duty competition quality screw in studs are machined from alloy steel, heat treated, thread rolled and ground to produce the finest quality stud. Used to convert heads from pressed in type studs, after machining or fitted to heads that are machined to accept 7/16" UNC threaded studs, as listed in our Roller Rocker and head application charts.
Guide plates type 'A' are a press fit onto studs fitted to '63 - '71 Holden stud type six cylinder heads. All other guide plates may require head machining, studs and hardened pushrods.
Yella Terra valves and retainers are available separately. Valve springs are sold in sets. Yella Terra VALVES are made from the finest quality steels - inlet valves are produced from "Silchrome" alloy steel and exhaust valves from stainless non magnetic high temperature resistant 21-4N material. All valves have our exclusive "Double Diamond" patented surface hardening process Tuftride - this heat and chemical treatment imparts an extremely hard dark grey, so called "Black" surface over the entire valve. These valves have incredible resistance to scuffing, stem and head wear. They are sold individually.
Yella Terra VALVE SPRINGS are produced from the finest valve spring wire and are only available in sets and should be replaced as such. Correct valve spring selection is critical to the performance of highly modified engines, it is almost impossible for an assembled head to have the optimum springs fitted at the factory unless ordered. Where radical cam profiles and high RPM'S are anticipated the final selection of valve springs should be determined by the camshaft supplier and engine builder.
Yella Terra CHROME MOLY STEEL VALVE SPRING RETAINERS are precision machined from aircraft quality 4140 chrome moly steel, heat treated and blackened, their exceptional strength allows reliable operation in the highest forms of motorsport. Most Yella Terra retainers are lighter in weight than standard. They are produced in a variety of spring sizes, for single and dual springs, with varying offsets to allow the use of taller than standard springs. Additional valve spring retainers are listed separately.
