I have a 68 327/350 that I'm prepping for NCRS judging. The water pump is incorrect. I'm trying to determine the correct part. The judging manual says "38782608" is the correct part, which is only available as a vintage part. Is this the correct part #? In looking at some of these parts on ebay, there appear to be some subtle differences .. "long neck/short neck" and the pulley pattern for some is four holes and others is eight holes. I found another store that says the correct part for a 350 hp is "3759326" .. confusing to an amateur! Any advice greatly appreciated! (Car is away from home so I don't have it to compare to)
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Re: 68 327/350 water pump?
Suggest you contact Bill Mock for a rebuilt pump
phone 918-333-0748
Email: williamhmock@aol.comDick Whittington -
Re: 68 327/350 water pump?
Steven------
A waterpump using GM CASTING #3782608 was used for ALL 1968 Corvette small blocks. That's the number that's shown in the 68-69 NCRS JG and the JG is 100% correct on this point. NO 1968 Corvette with L-79 ever originally used the GM #3859326. ALL 1967 Corvettes with L-79 used that casting, but NO 1968's did. Perhaps, that's where the confusion is created.
The 3782608 casting is a VERY common casting as it was used for most Chevrolet small blocks for many years. 1968 versions of it were dated.In Appreciation of John HinckleyComment
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Re: 68 327/350 water pump?
My 68 327/300 engine uses the 3782608 pump. Mine is original best I know. I was fooled when I ebayed a "replacement" I bought for rebuild as a spare. The replacement came from a full size car (same housing #3782608) but with a considerably larger pulley on the pump than the one on my car. That is why some of them have the 8 holes pulleys with the two different center diameters covered either way depending on your application. But the larger diameter may not fit your fan clutch so be careful.Comment
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Re: 68 327/350 water pump?
Dan------
The replacement you bought was very likely a pump that had been rebuilt before with some part changes.
ALL 3782608 pumps originally used 5/8" pilot shafts (the part that goes through the pulley center hole and into the orifice on the fan clutch). NO 3782608 ever originally used a 3/4" pilot (the only other size I know of).
Most original pumps used a waterpump flange with only 1 bolt pattern (i.e. 4 tapped holes). New GM SERVICE pumps as well as most rebuilt pumps use a flange with dual bolt patterns (i.e. 8 tapped holes). Some PRODUCTION pumps even used hubs with the dual bolt pattern. The dual pattern hubs are a little larger in OD than the single pattern but they will work just fine with all original pullies.
The dual pattern hubs should fit any pulley ever originally used on a Corvette. However, 1971 and later Corvettes require a waterpump with a 3/4" pilot. NONE of these ever originally used a 3782608 pump casting, though.In Appreciation of John HinckleyComment
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Re: 68 327/350 water pump?
thanks to all for these helpful comments - now more likely to get it done right the first time!Comment
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Re: 68 327/350 water pump?
Joe
I think you are right and I bought the housing based on Part number not realizing the shaft and all would/could be different. I also do have a 8 bolt hole 3782608 in my collection of "stuff" and it too may very well be a rebuilt unit too. Thanks for the feedback.Comment
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Re: 68 327/350 water pump?
I think you are right and I bought the housing based on Part number not realizing the shaft and all would/could be different. I also do have a 8 bolt hole 3782608 in my collection of "stuff" and it too may very well be a rebuilt unit too. Thanks for the feedback.
Aye, matey...thar's your problem!
That's NOT a part number on the pump housing. It's the housing's casting number.
A given casting underwent secondary operations (drill, tap for external bypass if required, Etc.) and then was assembled (impeller, shaft, bearing, drive hub, rear plate). Those variables created a specific GM part number that appears NOWHERE on the finished assy.
So, to get a given part 'right', you need to know/understand all the little nuiassances of the correct finished part...Comment
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