1969 427/390 Replacement Water Pump

[Art Ives]

The water pump I have for my 427 that I am rebuilding does not have either the GM name or part number. What is the correct water pump that I should replace it with and should it be dated? My build date for the car is 6/21/69. I would appreciate any help that anyone can give me. Thanks , Art Ives

[Joe L.]

Re: 1969 427/390 Replacement Water Pump

Art------

For 1969 Corvette big block applications, there were 2 different water pump castings utilized. Early production cars used the GM #3856284 which is the same pump casting used for all previous Corvette big blocks and most big blocks used in all other Chevrolet applications from 1965 through 1968. However, your car is a late build car and I consider it very likely that it was equipped with the GM #3940960 water pump. The 3940960 is one of the rarer big block water pump castings inasmuch as it was only used in PRODUCTION for late 1969 and all 1970 Corvettes as well as a few HD truck applications. However, it was also used for SERVICE water pumps manufactured during the late 1969 and 1970 time period and applicable to all 1965-70 Corvette applications as well as most 1965-68 big block applications in passenger cars and light trucks. So, although not common, these castings can be found without a huge amount of effort.

These castings were dated, although the dating is virtually indiscernable with the pump and pullies mounted in the car.

One other thing: if you were to find a GM #3856284 which is dated about the same as your engine casting dates, you could use it, too. It likely was originally fitted to a Corvette engine built about the same time that your car's engine was built, so it could have resided on yours. I think that it's unlikely that you'll find a '284' pump dated like this, but it's not beyond the realm of possibility. When the change was made to the '960' pump for PRODUCTION, the '960' also replaced the '284' for SERVICE applications.

[Joe L.]

Re: 1969 427/390 Replacement Water Pump

Art------

For 1969 Corvette big block applications, there were 2 different water pump castings utilized. Early production cars used the GM #3856284 which is the same pump casting used for all previous Corvette big blocks and most big blocks used in all other Chevrolet applications from 1965 through 1968. However, your car is a late build car and I consider it very likely that it was equipped with the GM #3940960 water pump. The 3940960 is one of the rarer big block water pump castings inasmuch as it was only used in PRODUCTION for late 1969 and all 1970 Corvettes as well as a few HD truck applications. However, it was also used for SERVICE water pumps manufactured during the late 1969 and 1970 time period and applicable to all 1965-70 Corvette applications as well as most 1965-68 big block applications in passenger cars and light trucks. So, although not common, these castings can be found without a huge amount of effort.

These castings were dated, although the dating is virtually indiscernable with the pump and pullies mounted in the car.

One other thing: if you were to find a GM #3856284 which is dated about the same as your engine casting dates, you could use it, too. It likely was originally fitted to a Corvette engine built about the same time that your car's engine was built, so it could have resided on yours. I think that it's unlikely that you'll find a '284' pump dated like this, but it's not beyond the realm of possibility. When the change was made to the '960' pump for PRODUCTION, the '960' also replaced the '284' for SERVICE applications.

[Art Ives]

Re: 1969 427/390 Replacement Water Pump

Thanks Joe, I need to get busy looking for a pump. I'm starting assembly of the engine and want it to be right when I set it in place. Do you know any good sources? Art

[Art Ives]

Re: 1969 427/390 Replacement Water Pump

Thanks Joe, I need to get busy looking for a pump. I'm starting assembly of the engine and want it to be right when I set it in place. Do you know any good sources? Art

[Joe L.]

Re: 1969 427/390 Replacement Water Pump

Art------

1) Dr. Rebuild (although I don't know if he carries this particular pump)

2) John Pirkle (pirklesr@juno.com)

3) Goat Hill Classics

[Joe L.]

Re: 1969 427/390 Replacement Water Pump

Art------

1) Dr. Rebuild (although I don't know if he carries this particular pump)

2) John Pirkle (pirklesr@juno.com)

3) Goat Hill Classics

[Jack H.]

Request for NTL comment

Info Joe gave regarding use of 3940960 pump in '69 is interesting and new to me--I know I don't know.... Current '68-69 NCRS Technical Information Manual and Judging Guide (JG book) reads:

"The small block water pump for both years is part number 3782608. The 427 water pump for both years is part number 3856284"

I presume this text is incorrect because the numbers referenced are not water pump part numbers, simple water pump body/housing casting numbers. Going forward the '70-72 JG book's text on BB water pump housing castings is complex and paraphrasing it we get:

(1) Primary BB pump for '70-'71 era was casting 3856284.
(2) Primary BB pump for '72 era was casting 386100.
(3) BB pump casting 3990277 was also used in '70 as early as VIN 2077

Neither book makes mention of the 3940960 pump casting, but Goat Hill's ad in Driveline lists all four of these housing cast numbers.... I suspect Joe Lucia is correct because it's a cold day in (*^^ when I've seen him to be wrong! But, the rule on this discussion board is nothing is 'official' without a post from a National Team Leader.

I'd like to update/correct my NCRS chapter JG books with the 'new' knowledge here (use of 3940960 pump housing), but this needs official National Team Leader (NTL) sanction. Could an appropriate NCRS judging official please acknowledge the '68-69 JG book's text is in error and supply appropriate corrective text?

[Jack H.]

Request for NTL comment

Info Joe gave regarding use of 3940960 pump in '69 is interesting and new to me--I know I don't know.... Current '68-69 NCRS Technical Information Manual and Judging Guide (JG book) reads:

"The small block water pump for both years is part number 3782608. The 427 water pump for both years is part number 3856284"

I presume this text is incorrect because the numbers referenced are not water pump part numbers, simple water pump body/housing casting numbers. Going forward the '70-72 JG book's text on BB water pump housing castings is complex and paraphrasing it we get:

(1) Primary BB pump for '70-'71 era was casting 3856284.
(2) Primary BB pump for '72 era was casting 386100.
(3) BB pump casting 3990277 was also used in '70 as early as VIN 2077

Neither book makes mention of the 3940960 pump casting, but Goat Hill's ad in Driveline lists all four of these housing cast numbers.... I suspect Joe Lucia is correct because it's a cold day in (*^^ when I've seen him to be wrong! But, the rule on this discussion board is nothing is 'official' without a post from a National Team Leader.

I'd like to update/correct my NCRS chapter JG books with the 'new' knowledge here (use of 3940960 pump housing), but this needs official National Team Leader (NTL) sanction. Could an appropriate NCRS judging official please acknowledge the '68-69 JG book's text is in error and supply appropriate corrective text?

[Art Ives]

Re: Request for NTL comment

I called a dealer advertising pumps in Hemmings and he tells me I'm wrong and it is an 065 and that the 284 is for mid years. Now I'm totally confused. I hope we can get a solid answer. Thanks, Art Ives

[Art Ives]

Re: Request for NTL comment

I called a dealer advertising pumps in Hemmings and he tells me I'm wrong and it is an 065 and that the 284 is for mid years. Now I'm totally confused. I hope we can get a solid answer. Thanks, Art Ives

[Donald S.]

Re: 1969 BB Water Pump

I beleive Joe is correct in his comments regarding the usage of the 3940960 water pump in late 1969 big block cars. As being an owner of a November build 427/435, I can confirm that mine still has the original 3940960 pump with a casting date of J 28 9. Don Smith #28087

[Donald S.]

Re: 1969 BB Water Pump

I beleive Joe is correct in his comments regarding the usage of the 3940960 water pump in late 1969 big block cars. As being an owner of a November build 427/435, I can confirm that mine still has the original 3940960 pump with a casting date of J 28 9. Don Smith #28087

[Joe L.]

Re: Request for NTL comment

Art-----

No big block water pump casting number ending with the "065" was used in ANY big block Corvette. Ever. The "065" water pump casting was GM casting #3931065. This was a LONG LEG big block water pump which was first used for the 1969 model year. Beginning in 1969, the long leg water pumps were used for virtually all Chevrolet passenger car and light truck applications with BOTH big block and small block engines EXCEPT Corvettes. Corvettes continued to use short leg water pump design for big block through the end of PRODUCTION in 1974 and for small block through 1991. Obviously, of course, the big block and small block water pump castings were different.

It's surprising how many folks that ought to know better (like water pump dealers) think that LONG LEG style water pumps were used for ALL 1969+ applications. Mostly, they're right. But, they're not correct for ALL Corvettes and some 75-79 Chevrolet Monzas (and its other GM clones) with 262 and 305 cid V-8 engines. Those applications all used short leg water pumps. The 55-70 Corvette (and all 1955-68 other Chevrolet small block) short leg small block pumps have a slightly shorter leg length than the 71-91 Corvette short leg pumps, though. All 65-74 Corvette (and 65-68 all Chevrolet) big block water pumps have the same leg length.

[Joe L.]

Re: Request for NTL comment

Art-----

No big block water pump casting number ending with the "065" was used in ANY big block Corvette. Ever. The "065" water pump casting was GM casting #3931065. This was a LONG LEG big block water pump which was first used for the 1969 model year. Beginning in 1969, the long leg water pumps were used for virtually all Chevrolet passenger car and light truck applications with BOTH big block and small block engines EXCEPT Corvettes. Corvettes continued to use short leg water pump design for big block through the end of PRODUCTION in 1974 and for small block through 1991. Obviously, of course, the big block and small block water pump castings were different.

It's surprising how many folks that ought to know better (like water pump dealers) think that LONG LEG style water pumps were used for ALL 1969+ applications. Mostly, they're right. But, they're not correct for ALL Corvettes and some 75-79 Chevrolet Monzas (and its other GM clones) with 262 and 305 cid V-8 engines. Those applications all used short leg water pumps. The 55-70 Corvette (and all 1955-68 other Chevrolet small block) short leg small block pumps have a slightly shorter leg length than the 71-91 Corvette short leg pumps, though. All 65-74 Corvette (and 65-68 all Chevrolet) big block water pumps have the same leg length.