1962 water pump

[Jerry K.]

I have a question about grind markes on the flashin of casting#3782609?
There is also a flat surface on the top front, where the overflow elbow screws in. Two holes, one top and one bottom , my old pump had two on the bottom. Is this a service part?

[Jack H.]

Re: 1962 water pump

These pumps are being reproduced (and not too well) these days. What's 'wrong' with the reproductions is they used a late model pump housing ('326?) as the 'core' to copy and did a pretty poor job in the process.

If memory serves, once such place for retail purchase of the 'reproduction' is Zip Products and someone said they thought the actual source was in Turkey. But, that's hearsay...

Now, what makes these pumps easy to spot is the upper boss. The original '609 pumps had a gently rounded front side surface to the boss that just 'barely' cleared the rear edge of a pulley attached to the pump. Plus, the top side diameter of the boss was just wide enough to accept drill and tap for the 1/2" NPT bypass elbow used by Corvette.

The original '609 pump had a rather short life because other cars/trucks wanted the external bypass feature but with a larger, 3/4" NPT fitting. There just wasn't enough 'meat' on the '609 housing to hack that big of a bypass.

So, the '609 housing was replaced with a '175 casting (3839175) and then a '32 casting (3859326). Both the '175 and '326 castings solved the problem of giving the upper boss more surface area by putting a 'flat' across the front surface to eliminate the interfering curvature and give clearance for the rear edge of the pulley.

Another difference between the current 'reproduction' water pumps and real McCoy originals lies in the font and placement of the casting number. The reproduction pumps have font that LOOKS NOTHING LIKE that of an original.

From what you describe, it sounds to me like you've gotten one of the reproduction pumps... It should fit and function, but I wouldn't give you much chance at getting the pump past a savvy judge!

On the other hand, these pumps are reasonably priced (around $125) whereas real McCoy '609 pumps have been known to sell for $500-800 recently...

Unfortunately, NCRS does NOT recognize the '175 version of the water pump as being a legitimate factory original Corvette component. But, when you lay the three pumps side by side, you can see the running change differences that logically accompany the casting number progression...

[Jack H.]

Re: 1962 water pump

BTW, here's a 'family' shot of the three water pumps. From right to left: '609, '175 and '326...

[John D.]

Re: 1962 water pump

I have a question about grind markes on the flashin of casting#3782609?
There is also a flat surface on the top front, where the overflow elbow screws in. Two holes, one top and one bottom , my old pump had two on the bottom. Is this a service part?

Gerald, What kind of hardware is holding on the back cover plate. Slotted screws or hex head? Thanks, John

[Jerry K.]

Re: 1962 water pump

Hex head 7/16 bolts with star washers.

[John F.]

Re: 1962 water pump

Call Bill Mock who advertises in the Driveline at (918)333-0748. He is an expert on 61/62 waterpumps. John

[Jack H.]

Re: 1962 water pump

Just a note...the '609 water pump continued on into the '63 model year so the part isn't just a straight-axle piece...

[Joe C.]

Re: 1962 water pump

BTW, here's a 'family' shot of the three water pumps. From right to left: '609, '175 and '326...

Jack,

If you still have that 326 pump available, please tell me what the "GM" number is, above the part number. Also, are the heater outlet and the bypass outlet both the same size (1/2" NPT)? The photo shows 2 different hub styles. Do you know which type was used with the 326: the 4 or 8 hole?
Thanks,
Joe

[Jack H.]

Re: 1962 water pump

The water pump comparison photo was from my picture archive, the parts shown are long gone. Plus, this is a technical discussion board--not a swap meet; so no parts for sale.

On the 'GM Number', why does that matter? It's simply a GM internal designation of the casting source (plant, line, mold). Trying to match that aspect is futile as that it varied rather randomly...

Next, the Corvette (and Camaro) version of the waterpump used a 1/2" NPT bypass outlet while most passenger car and truck applications using the same basic casting had larger 3/4" NPT fittings. That's one of the differences between a raw casting number (appears on the part) and the final part number (appears nowhere on the part).

Hubs? Factory originals for Corvette all used a small hub with 4-hole configuration. You'll only see 'universal' hubs (either dual pattern drilled/tapped with eight holes or slotted) on pumps that were either late era service replacements or those that had been though the hands of a rebuilder (make a one fits all part for inventory simplification).

[Joe C.]

Re: 1962 water pump

The water pump comparison photo was from my picture archive, the parts shown are long gone. Plus, this is a technical discussion board--not a swap meet; so no parts for sale.

On the 'GM Number', why does that matter? It's simply a GM internal designation of the casting source (plant, line, mold). Trying to match that aspect is futile as that it varied rather randomly...

Next, the Corvette (and Camaro) version of the waterpump used a 1/2" NPT bypass outlet while most passenger car and truck applications using the same basic casting had larger 3/4" NPT fittings. That's one of the differences between a raw casting number (appears on the part) and the final part number (appears nowhere on the part).

Hubs? Factory originals for Corvette all used a small hub with 4-hole configuration. You'll only see 'universal' hubs (either dual pattern drilled/tapped with eight holes or slotted) on pumps that were either late era service replacements or those that had been though the hands of a rebuilder (make a one fits all part for inventory simplification).

Never ASSume. I don't want to buy anything!

"Available" means "available for you to look at", so that you can report back.

I was told that the GM number is relevant, as Corvette pumps used specific mold numbers only. Certain mold numbers would disqualify pumps from being Corvette specific.

[John H.]

Re: 1962 water pump

I was told that the GM number is relevant, as Corvette pumps used specific mold numbers only. Certain mold numbers would disqualify pumps from being Corvette specific.

Joe -

I doubt that. With Saginaw producing 50,000+ castings per day for Flint V-8, and Flint V-8 receiving/machining/assembling them, I can't imagine anyone at either end looking for pattern numbers within the same casting number batch to sort out for specific Corvette usage (2% of production). Sounds like an "internet legend".