So as I'm in the process of redoing my sbb engine (home build) for my 68 Skylark the one thing that stood out to me from the very first time I changed the oil is that the oil filter was much smaller/thinner than a stock filter. As I clean the block and heads I'm unearthing numbers. At the front of the block just below head are these #s 1241748, which after some research tells me it was cast anywhere from a 1962-1980. The # stamped on the heads is: 1382546 which if my research is correct are 68-74 and most likely 72-74 as the oil lubes through the push rods. Apparently the heads are not a factory match to the block. I couldn't find an engine code anywhere i.e., PP, WB, F, etc. When trying to find a filter to fit the pump, I had to go all the way to 1980 for a oil filter to fit from NAPA. So it's assumed the block and timing cover/oil pump are 1980, correct? Can I replace the timing cover/oil pump without any major alterations or issues? Or can I swap the oil pump? Should I? What am i losing in power by keeping what I have? I do plan to upgrade to a heavier street performance cam from TA. My oil pressure always seemed high especially at start up and under heavy acceleration.
The filter adapter may be different the timing cover unit as far as year . Did you use a small filter? A pf47? And the bottom of filter housing has metric cast in it? Then you have a v6 filter housing. That can be changed. But the best oiling upgrades would be a TA performance backgrooved front cam bearing installed as directed, drill out passage thru block for oil pickup tube. Drill to 1/2 inch. And round the 90 degree turn in block with a die grinder. With a 60 psi relief spring. Get a 76-80 350 pickup screen it's 5/8. Your not loosing power with the timing cover unless you have the hi volume oil pump which I would take out. . Is your 68 engine a original 4 barrel engine? If so your compression is an actual 9.2 if it has the factory Pistons. If it's a 2 barrel engine then expect about 8.2 with replacement head gaskets. Shaving heads .030 could net about 8.7 / .060 would net 9.45 on the lower compression Pistons. I would look at the crower level 3 cam advanced 4 degrees when degreed in.
With the amount of money my son has invested in his engine build, we opted for the new cover and pump from TA instead of trying to use the old one.
If in fact you do have the "Metric" oil pump cover, its no big deal, like Sean said, if your oil pressure is good, leave it. The "Metric" cover uses a smaller filter, whooptie dooo If you change your oil often, its a non issue, plus its less filter to fill up upon start-up.
Depends on what oil grade you run. 20w50 is to thick for these engines. Better with 10-30/10-40. It may have a hi volume oil pump kit . Up to 60 is fine for most uses. But there is a pressure relief to limit top pressure. but that's the wrong thing to focus on. How is hot oil pressure in gear at idle. Is it above 10psi without having to run 20-50 oil. 20-50 just hides the bearing problems until it's too late.
I run 10/30 usually semi-synthetic. If I recall hot oil at idle is around 10-15 psi. Moderate acceleration is goes up past 30 psi. At cold start up its pegged all the way.
It is entirely normal for oil pressure to be high (60-70 psi) with cold oil and a cold engine. As oil warms up, it thins out reducing pressure. As the timing cover heats up, the internal clearances in the oil pump increase, also, reducing oil pressure. The 350 needs 10 psi/1000 RPM. If your hot oil idle pressure is 10-15 psi, that is fine. It takes about 20 minutes at highway speeds to get oil as hot as it will get. After getting off the highway, and sitting at a traffic light in gear, see what the pressure is then. Then see what it goes to at higher RPM. If you have sufficient oil pressure at your WOT shift points, you are good to go.
Pegged all the way? Is that 50 /75 or more. 30 on acceleration if ok. You need atleast 10 psi for every 1000 rpm engine climbs. So at 1000 you should see atleast 20/ 2000/30psi. your overthinking. As long as pressure relief is cutting out at 60 don't worry about too much oil pressure