Spark Plugs By Year

How to read an AC Delco spark plug nomenclature.

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The following matrix of spark plugs used are for AC Delco as installed. Some of these may no longer be readily available or have been superseded by GM and can be used to cross-reference to another brand such as Autolite, Bosch, NGK, Champion, etc.

Year Engine AC Delco Spark Plug
1964 194/230 46N
  283/327 44/45
1965 194/230 46N
  283/327 44/45
  396 43N
1966 194/230 46N
  283/327 44/45
  396 43N
1967 194/230 46N
  283/327 44/45
  396 43N
1968 194/230 R46N
  307 R45S
  327 44
  396 43N/44N
1969 230/250 R46N
  307 R45S
  350 R44
  396 R43N *
1970 250 R46T
  307 R45
  350 R44
  396/402 R44T *
  454 R43T
1971 250 R46TS
  307/350 (L65) R45TS
  350 (L48)/402 R44TS
  454 (LS5) R43TS
1972 250 R46T
  All V8 R44T
     
     

* Early in 1970 the 3964290 cylinder head was recast to use the R44T tapered seat plugs so early castings may still use the R43N 'standard' plugs.