Wondering if any of the historians out there can tell me when the 2-piece oil pan stiffeners started (and were discontinued?) being installed on S30 engine types (240/260/280). Thanks.

I don't know when they were introduced, but they were still there on my 81 280zx (engine).

 

 

They are present on my very original 75 280z.

A casual poke thru the Parts Manual shows that the 280 oil pan part no. was first used in the fifth mo. of '71.

@kats photo of possibly HLS30-00003, seems to show there is no "welded mass" plate on the oil pan circa Q3 1969.

Some say the extra plate was to help reduce cracking due to vibration caused by the early crank imbalance.

 

 

 

Edited September 10, 20195 yr by 240260280

It is the two piece steel straps (one that also doubles as a header pipe heat shield) that use the existing oil pan bolts that I was referring to. Feedback so far indicates that they were installed on (all?) L24/26/28 engines beginning sometime in 1971.

I always assumed, right or wrong, that they were not present on 240z models. My 24k mile 6/72 240z does not have the two piece steel straps / braces.