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Discussion Starter · #1 · (Edited)
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 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 the clearances inside the oil pump or not checked, and is partly binding or in some cases of the oil pump has ingested, some small bits of metal or other foreign material.the standard high-performance oil pump drive shaft looks like the one below ,it has a steel collar and is made from a stronger than normal steel


It should never be used in a 400 type blocks, and I don't use them on any engine builds
the AARP style with the reduced cross-section of metal is the preferred type, when you do get around the checking the clearances between the gears of the oil pump, and a removable floor plate, the end play clearances should be no more than .003 maximum, .002 preferred, you'll see one driven gear and one drive gear, I normally pull off the driven gear and carefully drill of the 1/16 inch holes in the bottom of the gear tooth slot, at three places spaced vertically, and horizontally one third of the way around an up-and-down on those seven to 12 gear teeth have(depends on the pump your using) if done correctly and carefully this modification at least in theory aids the oil flow sporting that driven gear, as in most engine mods, no one thing does tell a lot, but the accumulation of a lot of little things and modifications, makes for a winning engine combination.

The bottom of a Chevrolet distributor housing can be modified to spray pressurized oil onto the distributor drive gear. The extra lubrication will reduce distributor gear and camshaft gear wear. This is especially important when the gear is used to drive non-standard accessories, such as a high volume oil pump, or a magneto that puts additional loads on it and the cam. When the distributor is installed, the bands at the bottom of the housing are designed to complete the internal right side lifter galley on all small and big block Chevrolet V-8’s and 90° V-6 engines. If you hand file a small vertical groove .030" wide x .030"( thats the diam. that crane recommends Ive always used the larger groove with no problemsdeep on the bottom band (above the gear), pressurized oil running between the two bands will be directed downward onto both the gear and the camThis procedure is recommended for all Chevrolet engines no matter what material gear (cast or bronze) or what type of camshaft (cast or steel) you are using
keep in mind the groove MUST be lined up with the cam gear when the distrib. is installed

another potential source of problems and noise that you should but know about is that, YOU must always install and aluminum bronze distributor gear on a steel cam normally these are roller cam's than normal distributor gear is made of what looks like cast-iron will not work on a steel roller cam a steel roller cam will quickly destroyed a standard gear that's why you must use the aluminum bronze gear.... unless , the steel cam has had pressed on cast-iron gear to match the standard distributor gear.
almost every sbc engine I build uses a standard voluum big block pump or a high voluum standard pressure oil pump with no problems at all, my 383 in my 1985 vette gets pulled out and checked , new rings and bearings just as a standard rebuild about every 18 months and not once has either the distrib. or cam gear show excessive or for that matter even measurable wear, the fact that I run a 9.5qt oil pan, with magnets that pick up all metalic dust, good oil filters, and 90% plus synthetic oil, a groove in the lower distributor oil band, that sprays a constant stream of oil onto the contact point I think is the main factor READ THIS http://www.melling.com/highvol.html http://www.melling.com/engoil.html http://www.melling.com/miscon.html
now think it thru,
(1)pressure is the RESULT of resistance to oil flow
(2) the high voluum pump can push about 25% more oil
(3) the oil pump bye-pass circuit limits the max pressure in either size pump to about 65lbs-75 lbs MAXIMUM before it BYE-PASSES all additional oil voluum
(4) the engine can accept and use only the max flow voluum that the engine passages can flow at the max pressure the pump provides , at any point less than max pressure the passages can flow only what the pressure and voluum provided by the pump supplies
(5)if the bearing clearances can flow more than the pump provides in voluum and pressure at any rpm level the film of cooling oil that provides a cushion between the bearing surfaces are at risk of not being supported and seperated by that cushion of oil
(6) now since the sweep voluum is greater with the high voluum pump it will reach that bye-pass circuits max pressure at about 25% lower rpms and supply a POTENTIALLY higher voluum of oil to the supply passages/bearings SO...
(7)all a high voluum pump does is provide the maximum oil flow the engine can use up to the max pressure allowed by the bye-pass circuit at a 25% lower rpm level if the system can reach max pressure, but it also supplies 25% more oil at every rpm level below that point to provide additional cooling and protection for the engine. and if the engine can flow more than the stock pump can provide the high voluum pump helps fill the need faster
(8)oil flow through the bearing clearances INCREASES at a faster rate as the rpms increase
(9) in most engines the oil flow can be provided by the stock pump IF the clearances are close to stock AND THE RPM LEVELS ARE KEPT IN THE idle-6000rpm range but if rpm levels exceed 6000rpm,or if bearing loads greatly exceed the stock hp levels, or the clearances are greater than stock the high voluum pump is a good idea
 
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