Oil Pump

[Jack J.]

Joe Lucia. Could you please identify an oil pump part number? #3848907 - Thanks in advance. Jack

[Joe L.]

Re: Oil Pump

Jack-----

GM #3848907 is a standard volume, high pressure oil pump. It was the pump originally used for later 1963 through 1965 small blocks with SHP, solid lifter engines. It was also originally used for 70-72 LT-1. Basically, this pump is the same as the standard pressure pump used on the vast majority of Corvette small blocks except for the pressure relief spring installed.

It was discontinued quite a few years ago and replaced by several supercessive part numbers. Currently, it's known as GM #12555884.

[Kevin Whiteley]

P/N Supercession

Joe,

When you write about supercession, do you mean 1) that the part was superceded, or 2) that the part number was superceded?

For example, let's say Company XYZ makes a "widget" and GM assigns P/N 123 to the widget. If company XYZ makes a better widget which replaces the first, does GM keep the same P/N or do they give it a new number, such as 456?

Also, using the above example, if Company XYZ has been making the same widget for 25 years, and obviously, GM produces new models and variations, will GM keep the same P/N throughout the entire 25 years, or will they "update" the 123 p/n to a new p/n, such as 987, even though the part has never changed?

[Joe L.]

Re: P/N Supercession

Kevin-----

The only rule is that there is no set rule. IN GENERAL, if a part changes, a new part number will be assigned. However, that's not always the case, sometimes a part will be revised through a change to the original specifications for that part number. If the manufacturer for the part changes, that doesn't necessarily mean that a new part number will be assigned. Sometimes that will happen but other times it does not.

I've seen cases in which a part changes only slightly, but a new part number is assigned. I've seen other cases in which a part changes to what I regard as a significant degree but the part number does not change; it is, apparently, handled through a revision to the specifications OR it's a change which is allowed by the original specs. In general, a significant change to a part without a part number change is the exception rather than the rule.

Non-engineering spec changes may occur to a part and these rarely, if ever, result in a new part number. For example, head markings on bolts may change as a result of a change in manufacturer while the part number remains the same. Tooling changes may result in a part being formed differently (and appear differently configured), but that will not cause the part number to change. There's actually quite a bit of "latitude" allowed in the specifications for a part. GM has relatively "tight" specs, but they're not like a military specification (mil-spec).

Very rarely, if ever, will a part number change if there is absolutely no change in the part. GM has offerred some parts for 40 years under the original part number. There are not a lot of parts that fall into this category but there are some.