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Below is a picture of 2 water pumps wiht the same casting number 3782608. The black one is date coded H188 and the orange one is date coded H246. There are several differences in the casting. The black one has several additional bosses between the bolt holes and 2 raised ribs on the right side. The orange one doesn’t have extraboss or the raised ribs and the backing plate holes are drilled thru. I am only concerned with the casting differences. My question is what would be the correct pump for a 69 L46 with a build date on Nov 68.
Easy answer! Look closely at the one with the raised ribs and you'll see a 'T' emboss near the casting number. That designates Tonawanda as the casting source (WRONG part for a SB Corvette!).
Flip the other one over and you should find an 'S' embossed on the rear indicating a Saginaw foundry product. That's the one you want/need...
Don't be misled by the flanges to which the fan bolts--the orange pump has been rebuilt by a major rebuilder and they have put the universal mount on it--the flange/mount should be like the one on the black pump. (And, as Jack has indicated, the orange pump is correct)
Mike I hope you are not basing your assertion that the orange pump has been rebuilt solely on the universal mount flange. While I know that is a commonly held belief -- I know of one 1970 small block with a water pump with such a flange, and the water pump has never been off the engine. My guess is that if there is one such water pump, there are many.
I can't see either of the pictures you posted. However, from your description I agree with Jack that you have Tonawanda and Saginaw cast pumps and only the Saginaw cast pumps are correct for a Corvette small block.
Notwithstanding the above, there are MANY subtle and not-so-subtle differences in Saginaw-cast '608' waterpump castings over the many years of the manufacture of this casting. Some folks think that the differences only involved "dates" versus "no dates". It's a lot more than that, though. However, I don't think that any of these differences are a judged item, if they are even known to most judges.
Also, I agree with Terry. The waterpump shaft flanges on PRODUCTION waterpumps were GENERALLY of the single bolt pattern design. However, there were PLENTY of exceptions to this. The Flint engine plant manufactured both PRODUCTION and SERVICE waterpumps. GENERALLY, the PRODUCTION pumps had the single pattern flanges and the SERVICE pumps had the dual pattern flanges. However, there was absolutely no reason why Flint could not have installed the dual pattern flanges on PRODUCTION pumps and, in many cases, they did just that.
Terry my original owner 1970 350/300 built in July left the St Louis factory with a universal mount flange on its water pump. I still have it in its original condition as removed by me in 1985 after giving me about 130K reliable service miles. Bearings still ok, just seeping coolant from the weep hole.
I had trouble with getting the picture loaded, but you should be able to see it in my second posting.
I checked the back of the orange pump and there was no indication of an "S" for Saginaw as Jack suggested. What would the application be for the Tonawanda (black) pump?
I know that the pulley flange may be incorrect, but I don't think the flange is judged. In fact, there is not much said about the pump in the 68-69 judging manual.
George,
The Tonawanda cast water pump would be appropriate for a Tonawanda built small block. Tonawanda built many small blocks for various Chevrolet cars and trucks, just none for Corvette.
You are right that the flange is not judged -- it is not visible with the fan and pulleys on the car. We know less about the flange than we would like because of that. However, when it is as visible as in your photograph, it is hard not to comment on it.
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