I checked the timing and I was not changed. Still running 8 degrees advance.
Thank you for the info on the recovery system.
I need to be more diligent on checking the fluid level.
Posts above have suggested many possibilities, but one possibility seems to be missing (unless I missed seeing it). Every 261/235 that I have taken apart has had debris inside the block, often being plugged at the rear of the block. After cleaning an over-heating 261 and a normal temperature 235, both engines ran at noticeably lower temperatures during the summer when idling.
I will also do a flush. I've been reading a few threads on this subject
