Most valve jobs or engine rebuilds will require some level of machining of the head surface. L-Series heads are designed for specific valve train sizing and geometry, so when the head is milled beyond a certain amount (7 thousandths), these cam tower shims must be installed to put the geometry back into alignment. Each kit includes 5 shims (one shim per cam tower), which will re-align the camshaft on one head by 15 thousandths. In the event that further adjustment is required, a second set of shims will be needed. (Note: The most an L-Series cylinder head should be shimmed is 45 thousandths.) Professional installation recommended.
Datsun 240Z, 260Z, 280Z, 280ZX
Datsun S30, S130
1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983