a manual gauge will have an actual plastic or copper line letting oil travel all the way to your gauge, probably from behind the distributor on top of the block....if you have an electrical gauge..it'd be a little sending unit with a wire to the gauge.....my old moderate 318 had WAYY more pressure than that...as in 60 at startup when it was cold, then finally down to 30-35 when warm....i have heard of the stock oil pump spring going weak...causing low pressure...kinda like when a mech fuel pump starts to go...it'll still pump some...but not enough to keep up.
