Hi all,
Recently we've been entertained by some spirited debate about dual cast date 7th & 8th month 1973 cast JP blocks (thread seems to have vaporised).
Reflecting back on what Mike 73 has said about the casting marks found inside the crankcases of Holden red 6's it would seem that Holden have been tinkering for years with different compositions of the cast iron alloys used to make our faithful old power plants. If the conclusions reached from Mikes research are correct then not all 202 blocks, whether they be eg: QL, JL or JP, are metalurgically the same.
I suspect these dual cast date JP blocks will also have these casting marks inside the crankcase and wondered if they match up with any of the casting mark combinations found in earlier production QL,JL or JP blocks.
Also I was pondering this question and feel it needs to be asked:
Does anyone have, or know of, or ever seen a dual cast date 7th or 8th month 73 JL or QL 202 block?