I can't even list all the things I have done and tried with the engine. I kept a journal of the driving restoration of 10 years, which is 6 pages long in small print.
Learned a lot about which parts are OK to replace with remanufactured or NOS parts and which aren't.
Tried every multi grade oil there is and every additive.
Today, I like the idea of pure organic detergent oil and no modern additives or multigrades.
Alright - so I could even go with SAE40 and start at low temps ... I do that this weekend.
That is good thinking to keep it a cooling issue.
It's just hard to figure out if the oil pressure drops because of higher temps or the temperature goes up because the oil pressure drops.
One seems to cause the other to raise or drop respectively.
The cooling improvement I made a couple of years ago only slowed down the oil pressure drop, but couldn't prevent it.
I went through 3 old radiators, before I recored the last one with 3 core, which made a big difference after 8 years of heating up.
I even have the rare taller core, which I dropped down an inch to get closer to the water pump, which is short shaft and original lower 62 position.
The fan has always been about 3/8" close to the radiator - maybe that is just too close.
But no worries really - Before the internet and learning more about these engines and trucks (Thanks Stovebolt!), I drove this engine with the previous 4.11 rear and often pegged water temp on TX and s-CA freeways.
In the end I ran straight water with no thermostat.
No cracked head or any problems ever.
Can't kill those engines unless you do something really bad or wrong, it seems.
I just keep experimenting with higher grade oils and just wait until I can afford a second driver next year, to retire my old friend and partner to mostly in-town cruising.
The 261 short block I am trying to find will go with my NOS 848 head and all the other parts I got already.
I plan to put it into a 47/48 chevy coupe I want to find next year, which will do all the hot freeway long distance driving in the future.
I will learn more about cooling and oil pressure then, I am sure.
