Page 220 of 2008 Performance Parts by Ford Racing Performance Parts

engine building tips specs valve springs and things valve springs are a critical part of valve train operation they re designed to exert a specific load at a specific installed height thus spring selection and installation are important a single spring is generally used for stock engines dual or triple springs are often necessary for performance applications to increase the load for a given installed height if installed height isn t sufficient to handle camshaft lobe lift coil bind may occur rocker arms and studs 429 boss fe engines and some 4-cylinder rocker arms are shaft-mounted while others are individually mounted in several ways as shown in the illustration a non-adjustable stud is used in production engines with hydraulic cams mechanical camshafts require rocker arm adjustment to set valve lash hydraulic cams with anti pump-up lifters also require adjustment installed spring height is the distance from the spring seat to the bottom of the valve retainer shims can be used under the spring to change spring height if installed under stamped seat shims and seat must have same outside diameter spring seats on most production engines consist of a boss machined in the head on which the spring pilots on stock performance engines 302 boss 351c boss and ho 429 cj/scj and boss the head is flat and the spring sits in stamped spring seat ford racing offers spring seats for use with ford racing aluminum cylinder heads to prevent damage to the spring seat area this is a conventional rocker arm with closetolerance slot in head to guide push rods and maintain rocker arm alignment can be used with mechanical or hydraulic camshafts usage all 289 high-performance and 1963-661/2 standard 289 shown here is a rail rocker arm with loose-fit hole in cylinder head for push rods the u-shaped rocker arms maintain alignment can only be used with hydraulic camshafts usage 19661/2-1968 standard 289 1968-76 302 and 351w the illustration above is typical of 351c-351m-400 canted valve engines 429-460 engines are similar the rocker arm is mounted on a slotted pedestal moves on a sled fulcrum and is retained by a bolt 351c boss engines use the 302 boss type valve train also used on 429 cj/scj 1968-72 429/460 with hydraulic camshafts use a screw-in positive stop stud 1973 and later 429/460 have the 351c-type slotted pedestal here is a modified valve train to convert rail rocker arm design for mechanical cam requires conventional rocker arms guide plates hardened pushrods they rub on plates and threaded adjustable rocker studs requires different guide plate than the one used with a similar 302 boss setup usage 289/302/351w with mechanical camshaft a modified pedestal is used on 1978 and later 302/351w engines a stamped fulcrum guide is used with each pair of rocker arms 218 techline 800 ford788

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