1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 HYDRAULIC TAPPET

Part Number: 91-636

HYDRAULIC TAPPET - Part Number 91-636
All of Jim's Billet Tappet Blocks are made from 7075-T651 with a tensile strength of 83,000 psi which is double the amount of 6061-T6 and almost triple the amount of cast tappet blocks. These tappet block are machined to the center line of the cam and hold to + .002 of an inch. Also, the bores are held perpendiculr to the mounting flante to + .0002 of an inch. Fits Shovel Big Twins 53-84, use 1/4" - 20 screws. From late 1976 thru 1984, use 1/4" -24 screws. From 1953 thru early 1976, do not use the early tapered 1/4" - 24 screws on these blocks unless you provide a counter sink for that style screw. These blocks are designed to accomodate a gross valve lift of .550 at the valves. This is about .350 at the tappets, leaving a clearance of .035 roller to block free play. Use with stock tappet OEM 18522-53 or Midwest tappet part No. 91-285.
High performance 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974

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