Oil pump shim

[slowpoke]

just shimmed my oil pump again had 5 dimes, now upped to 8 soon as i start engine oil pressure only climbed to 32 psi (used to be 42 when cold) then fluctuated to 28 back to 32 up and down for about 4 minutes then climbed to 45 at 900 rpm once it settled i raised rpm to 1300 and it hit 51 psi. what pressure does the bypass ontop of oil filter blow of at. i pulled allen plug out to check thats its up datted it is. didnt try to pull it out though. could that be what caused fluctuation was a little scarry. bolts in oil pump o ring to out side by cotter pin. oil filter 2 days old.