Chevy oil pumps DON'T pump oil back into the oil pan, they re-circulate oil from the pressurized side to the oil pump back to the intake side, of the oil pump, but only if the bypass pressure is high enough to fully open the bypass valve spring, back to the intake side, of the oil pump
I was asked recently, as to my best guess, as to why a recently installed oil pump was making noise,
oil pumps rarely make much noise, unless, the drive shaft driving the oil pump, is rubbing on the block which will happen if you install a standard drive shaft in a 400 type small block which requires the drive shaft with the smaller diameter midsection. (what was going on in this case) Or you forget to install that little metal or nylon collar that keeps it aligned, or if your drive shaft has one the little spring clip, and remember to install the shaft along with the oil pump from...
Do I need an aftermarket oil pump shaft if I'm not using a hi-vol pump? I have plenty stock SBC shafts available.
Application" Street 11:1, Dart block SHP, mechanical cam motor with a melling select std volume std pressure pump.
Thank you,
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theres seems to be a lot of mis-information about , how the oil pump regulates its pressure curve, and the related subject of shimming oil pump springs and how your oil pumps pressure bye-pass circuit works.
PRESSURE, that you see displayed on the oil pressure gauge is a measure of the RESISTANCE to oil FLOW thru the engines clearances and its dependent on moth flow volume and oil viscosity, plus the cross sectional area of those clearance,s, but remember the oil viscosity changes with temperature.
assuming the proper bearing clearances and proper oil pump, was...
now if the oil pump pickup is mounted correctly at between about 3/8"-1/2" off the oil pan floor surface and that pickups been properly brazed so it can't move, and if the oil pumps properly mounted , to the rear main cap it should be pumping oil. Id suggest you pull the oil filter just for a test, and put a large oil pan under the the engine to test the oil pump, you spin the oil pump and have a buddy observe if oils flowing out of the oil filter feed, when you spin the oil pump, if it is nearly instantly puking oil the issues not the oil pump, or its pick-up.
keep in mind the oil pumps spinning at about 650 rpm at idle, your drill or hand crank may not be rotating the oil pump gears at anything close to that rpm and if you failed to prefill the oil filter it may take some time for the filter and oil cooler lines to fill and pressurize.
and if you left out an oil passage plug someplace it never will fully pressurize.
chevy oil pump drive shafts are available in several lengths, because various brands of oil pumps vary considerably in the length required.
you can also install a BBC oil pump on a SBC engine, in some cases, and applications.
if your spinning an oil pump priming tool and not feeling any resistance verify the oil pump to distributor gear drive shaft is spinning the oil pump when you spin the priming tool,
there should be
about vertical .050- .060 play in the oil pump drive with the distributor clamped in the intake
ideally the shaft should have about .050-.060 clearance, look over the chart and the common oil pump drive shaft length listed
there are several length and several vendors, you'll need to measure accurately and maybe modify any oil pump drive shaft for the correct clearance!
