Vaanth did a good job. I have to show it.
Timing covers for the LA engine series and the A engine series varied over the years with several similar but different covers as follows:
- LA Engines
- 1964 - 1968 LA engines
- 1969 and some late 1968 LA engines
- 1970 - 1977 LA Engines
- 1978 - 1992 LA Engines
- A Engines
- 1957 - 1961 A engines
- 1962 - 1966 A engines
The following sections describe the different timing covers.
The LA engines include the 273, 318, 340, and 360. Four timing covers were used for these engines from 1964 through 1992. The covers were mostly the same with differences in the timing scale location and structure, the mating vibration dampers, plus associated water pump revisions and a seal change.
The 1964 - 1968 273, 1967 - 1968 318, and 1968 340 were equipped with a cast aluminum timing cover without a cast in timing tab. The separate tab mounted to the lower water pump bolts with the timing scale on the passenger side with matching damper, or harmonic balancer, for use with the driver hose inlet cast iron water pump. This is the same cover as the 318 A engine which used the extra bolt hole on the left engine side. The extra hole is unused on the LA engine.
The following images show the timing cover for the 1964 - 1968 applications and the separate bolt on timing tab, or scale:
1969 and some late 1968 LA engines including the 273, 318, and 340 have the timing scale cast into the cover housing on the passenger side, and a matching marked damper. The extra bolt hole from the A engine usage was removed.
The following image shows the 1969 and late 1968 cover:
The cast in timing scale was relocated to the driver side for 1970, with the new aluminum water pump with hose inlet on the passenger side, along with matching damper with relocated marks. This cover was used through 1977 until it was revised starting with the 1978 318 engines to allow the seal to be replaced without removing the cover.
The following image shows a 1970-1977 timing cover:
The harmonic balance to timing cover seal changed in 1978. The seal could now be changed without cover removal. A new cover casting was introduced for the seal change. The 1978 - 1992 cover is directly interchangeable with the 1970 - 1977 cover. Some 1988 - 1991 covers used on Throttle Body Injection (TBI) engines have an unmachined fuel pump boss.
The following image shows a 1978 - 1991 timing cover:
The 1957 - 1961 A engines include the 301, 313, 318, and 326 Poly engines. Two timing covers were used for these engines from 1957 through 1967. The covers were the same except earlier versions were made from cast iron instead of cast aluminum like the later versions. 1956 A engine timing covers were different than the later A engines.
The 1957 - 1961 A engines used a timing cover that is physically the same as the 1961 - 1966 ( - 1967 for Canadian models) A engines cover, but made from cast iron rather than cast aluminum. The cover has an extra mounting hole on the driver side.
The following image shows the timing cover for 1956 - 1961 A engine:
The 1962 - 1966 ( - 1967 for Canadian models) 318 A engine has a similar cast aluminum cover with timing tab and matching damper as the 1964-1968 LA engines except it has an extra mounting hole on the driver side. These A engines use the same cast iron water pump as the 1964 - 1969 LA engine.
The following image shows the timing cover for 1962 - 1966 A engine:
Excerpted from Timing Covers, LA Engines and A Engines.
