IH: Engine Mechanicals

Rocker Modifications

  • A certain number of 1974 and 1975 XL & XLCH models were produced with modified rocker arms and rocker covers. These were machined to prevent interference between the rocker arm and the inside of the rocker cover due to a thickness variation in the covers. 1)
    • The only suspect rocker arm covers were the ones stamped with the letter “M” in the casting surface (which contains the pushrod entry holes). When replacing a rocker arm with the “M” stamped in the casting, you must grind 0.050“ off the top of the rocker prior to installation to provide enough clearance between it and the cover (when the valve opens).

Rocker Arms

Rocker arms on a 69 XLH 2)

HD Service Bulletin #678 dated December 17, 1974
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