Big block aluminum water pumps

[Steve Antonucci]

Hello,

Can anyone tell me a fact or two about 427 aluminum water pumps? I am wondering
in particular if Chevy made an aluminum long style water pump back in the 1969
timeframe. I know numerous ZL-1 Camaro's were built, but did they have long or
short style water pumps? The two Corvette ZL-1's probably used short style
water pumps, didn't they.

If the Camaro's did use an aluminum long nose water pump, does anyone know the correct part number? Are they scarcer than hen's teeth?

Steve

[Joe L.]

Re: Big block aluminum water pumps

Steve-----

For 1969, the last year that all aluminum big blocks were used in PRODUCTION, there were NO aluminum water pumps used. All 1969 ZL-1s used cast iron water pumps. The Corvettes used the short leg style and, I imagine, the Camaros used the long leg style. However, I'm really not sure about the Camaros. They may have been modified in some way for that application only to use the short leg pump. In any event, whatever pump was used it was cast iron.

As far as I know, there never was a GM long leg style big block aluminum waterpump. For 1970 an aluminum waterpump was released but it was available only in SERVICE. Some of the later SERVICE (crate) ZL-1 engine assemblies may have used the aluminum waterpump. But, it was never used in PRODUCTION.

[Steve Antonucci]

Re: Big block aluminum water pumps

Thanks for clearing that up Joe!

Perhaps that would explain why all ZL-1 engine pictures I have seen always
have the water pump painted black ( like all ofher steel parts ). It just
never registered before.

Steve

[frank mccracken]

Re: Big block aluminum water pumps

I was at a frieds garage the other day. On the floor was a gm BB aluminum water pump, short shaft. Natually I grabbed the casting # off it. 3975928. Can anyone give me any info on it?

[Bill Stephenson]

Re: Big block aluminum water pumps

-------Available over the counter for years. Joe L would know just how long. Have used 1 or 2 in the past and found them to operate pretty much exactly the same as thier cast-iron brother. Never came installed on any car with any engine combo that I can think of, although I would have to admit that I dont know what came on the two ZL1s. Hope this helps...........Bill S

[Clem Z.]

Re: Big block aluminum water pumps

competetion products sold them for years and they still list them in their ads. i am not sure if the ones the sell now are GM but the ones before had the GM casting numbers ground off.

[John H.]

Re: Big block aluminum water pumps

Dunno about the two Corvette ZL-1's, but I personally followed the first fifty (of 69) ZL-1's for Camaros down the engine dress line at Norwood in February of 1969 (anti-seize and torque wrenches in hand, no power tools allowed), and they all had cast iron water pumps.

[Joe L.]

Re: Big block aluminum water pumps

John, Bill and Frank-----

The 2 Corvettes with ZL-1 had cast iron waterpumps, too. They were the short leg variety. I don't know what leg length the Camaros used but, I expect, the 69s would have used the long leg style. GM never even sold a long leg style aluminum pump.

The GM casting #3975928 aluminum big block waterpump has been around since February, 1970. Originally, it was known as GM PART #3977630. In February, 1983 this was changed to GM #14058915 which is still available to this very day and still carries the 3975928 casting number.

I believe that this water pump was intended for L-88, ZL-1, and LS-7 applications. However, it was "too late to the party" to have been installed on any PRODUCTION L-88 or ZL-1 and the LS-7 was still-born as far as PRODUCTION cars go. I think that the 3977630 waterpump was installed, though, on SERVICE engine assemblies for L-88, ZL-1 and, perhaps, LS-7 produced after early 1970. Also, this waterpump was never used in PRODUCTION or, even, specified as SERVICE, for ANY 1971 Corvette LS-6 engine. It could NOT have been used for any Chevelle LS-6 engine, either, as all Chevelles with LS-6 used the long leg style waterpump.

Many GM parts references show this pump as being the correct SERVICE pump for "66-70 with HD" (i.e. L-88, ZL-1, and the still-born LS-7). However, this is a "retroactive" SERVICE specification. It's accurate in the sense that this was the INTENDED waterpump for those HD applications but it "never made it to the party in time". So, it IS the correct SERVICE pump for these engines. But, any engine representing itself as a PRODUCTION engine and equipped with one of these pumps is incorrect. Period.