I have 1976 dodge 360 engine that was just rebuilt. iT Has a stock oil pump When it idles it only has about 5-7 psi of oil pressure but when I rev it up to about 2,000 rpm it has little over 25 pounds of psi. I have reved it up to 6,200 rpm and it went little above 50 psi. I have already tried a diffrent gauge and it says the same thing. Is that normal oil pressure at idle or is there something wrong?