oil pressure and different weight oils

Yrs. ago I would have told you something was wrong, even in spite of the loose bearing clearances. But I've learned you really don't need a ton of oil pressure (remember back in the old days when we thought there was no such thing as too much oil pressure?). Several yrs. ago I built a 360 with pretty loose bearing clearances and it never ran much more oil pressure than yours and I worried about it the first year I ran it so the following winter I pulled some rod caps and main caps to look at the bearings. Much to my surprise the bearings looked just like the day I put them in. Just to ease my worries I installed a new HV pump that I blueprinted and assembled it with the same weight oil I always used. Oil pressure was exactly the same. I ran the crap out of that engine for yrs. and the day I sold it the darn thing held the same oil pressure as the day I put it together. Talked to the fellow I sold it to last summer and it's still going strong.

I bet if your bearing clearances were .001 tighter it'd have a bunch of oil pressure. But you need loose clearances in a performance engine. Switch to 20-w50 and I bet it picks up 10 psi pressure across the board