part num of original oil pump in 1969 L46 350?

[Keith M.]

Anyone know what the original oil pump GM part number was for 1969 L46? The Parts Catalog shows 3764547 but I do not know if that is original or service replacement. I have also seen 12555284

Thanks!

[Joe L.]

Re: part num of original oil pump in 1969 L46 350?

Anyone know what the original oil pump GM part number was for 1969 L46? The Parts Catalog shows 3764547 but I do not know if that is original or service replacement. I have also seen 12555284

Thanks!

Keith------


The original oil pump for 1969 L-46 was GM #3821979. GM #3764547 was a predecessor small block oil pump. It was discontinued in October, 1963 and replaced by the 3821979. Then, in February, 1974 the 3764547 "came back" (very unusual) and replaced the 3821979.

The 3764547 was again discontinued in July, 1989 and replaced by the GM #10055850 which was then discontinued in September, 1993 and replaced by GM #10055849. The latter was discontinued in July, 1996 and replaced by GM #12555284. Finally, the latter was discontinued and replaced by GM #93427692 which remain available.

With one exception, any of the above GM pumps will work fine for a 1969 L-46 and no one will know the difference. However, I do not recommend the latest iteration, GM #93427692. That pump is a high pressure pump whereas the original L-46 pump and all supersessions until the current were standard pressure. I do not recommend high pressure oil pumps for any 1955-96 small block except 1963-65 L-76/L-84 or 1970-72 LT-1.

[Keith M.]

Re: part num of original oil pump in 1969 L46 350?

Keith------


The original oil pump for 1969 L-46 was GM #3821979. GM #3764547 was a predecessor small block oil pump. It was discontinued in October, 1963 and replaced by the 3821979. Then, in February, 1974 the 3764547 "came back" (very unusual) and replaced the 3821979.

The 3764547 was again discontinued in July, 1989 and replaced by the GM #10055850 which was then discontinued in September, 1993 and replaced by GM #10055849. The latter was discontinued in July, 1996 and replaced by GM #12555284. Finally, the latter was discontinued and replaced by GM #93427692 which remain available.

With one exception, any of the above GM pumps will work fine for a 1969 L-46 and no one will know the difference. However, I do not recommend the latest iteration, GM #93427692. That pump is a high pressure pump whereas the original L-46 pump and all supersessions until the current were standard pressure. I do not recommend high pressure oil pumps for any 1955-96 small block except 1963-65 L-76/L-84 or 1970-72 LT-1.

Wow. Quite the legacy on these!! The good news is...I now know the original part number and have FOUR correct service replacement options! (excluded the latest per your recommendation which makes total sense).

Thank you!!

[Mark M.]

Re: part num of original oil pump in 1969 L46 350?

Where else do you get detailed answers like that. Glad your on the Corvette team Joe.

[Patrick H.]

Re: part num of original oil pump in 1969 L46 350?

Better yet, the Melling M-55 has been the unit that GM has been selling for years under their own part number.
Find an M-55 (not high volume or high pressure) and save some $.

[Gary B.]

Re: part num of original oil pump in 1969 L46 350?

Better yet, the Melling M-55 has been the unit that GM has been selling for years under their own part number.
Find an M-55 (not high volume or high pressure) and save some $.

And use an oil pressure relief spring that is likely to give you the oil pressure you desire. And not more than you desire.

Gary

[Joe L.]

Re: part num of original oil pump in 1969 L46 350?

Better yet, the Melling M-55 has been the unit that GM has been selling for years under their own part number.
Find an M-55 (not high volume or high pressure) and save some $.

Patrick------


I believe that most of the oil pumps I mentioned were of internal GM manufacture. The possible exceptions are the 12555284 and the 93427692. I have seen the 12555284 with GM casting numbers on the body and cover and I have seen some of this part number which do not have GM casting numbers on them. I believe the latter may be of Melling manufacture. However, I don't think they are a Melling M-55 in a box with a GM part number. I believe they are a Melling 10553 which is a higher quality Melling pump (which, incidentally, sells for about the same as a GM pump).

The latest and current iteration, the 93427692, I know nothing about. It may be a Melling M-55.

[Patrick H.]

Re: part num of original oil pump in 1969 L46 350?

Patrick------


I believe that most of the oil pumps I mentioned were of internal GM manufacture. The possible exceptions are the 12555284 and the 93427692. I have seen the 12555284 with GM casting numbers on the body and cover and I have seen some of this part number which do not have GM casting numbers on them. I believe the latter may be of Melling manufacture. However, I don't think they are a Melling M-55 in a box with a GM part number. I believe they are a Melling 10553 which is a higher quality Melling pump (which, incidentally, sells for about the same as a GM pump).

The latest and current iteration, the 93427692, I know nothing about. It may be a Melling M-55.

About 27 years ago I was dealing with Melling directly for an engine rebuild, and the rep at that time told me that they made the small block oil pumps for GM.
I assumed he was correct.

[Joe L.]

Re: part num of original oil pump in 1969 L46 350?

About 27 years ago I was dealing with Melling directly for an engine rebuild, and the rep at that time told me that they made the small block oil pumps for GM.
I assumed he was correct.

Patrick------

27 years ago is within the time frame that the GM #12555284 was available. As I mentioned, I have seen this pump with GM casting numbers on the major pump components and with non-GM casting numbers. I believe that the version with GM casting numbers was manufactured in-house by GM (probably at the Bay Cities, MI engine components plant). I also believe the version with non GM casting numbers was outsourced, very likely to Melling. So, that's very consistent with what you were told by Melling. However, if Melling supplied an "off-the-shelf" pump to GM, I believe it was the 10553 and not the M-55.

There's also another possibility. Melling may have manufactured another pump specifically for GM which met the specific GM specifications and was not otherwise sold under a Melling part number. Some major OEM suppliers have divisions which manufacture only OEM components, not sold in the aftermarket and Melling is likely one of them.

I do not think that any GM sourced pump was or is simply an M-55 in a GM box with GM part number. Every M-55 I have ever seen has the prominently displayed M-55 casting mark on the main body of the pump. I have never seen a GM pump with such a casting mark. As I mentioned, though, I have no familiarity with the latest GM #93427692. So, it's possible that pump is simply an M-55. But. this pump does not go back anywhere near 27 years.

[Joe L.]