077 Water pump question..

[Tom L.]

I've read in the archives that corvette water pumps use a cast iron impeller that differs from the stamped steel one that is offered by the vendors. My big block 077 pump has a stamped steep impeller so I took a bunch of time to look on the net for a pic of a cast impeller for this pump. I did find many pics of cast impellers from small blocks but none from big blocks. So here's my question... Did bo block pumps really come with a cast iron impeller or not? Specifically a '72 077 pump. A pic wpuld really help to confirm this. Thanks!!

[Joe L.]

Re: 077 Water pump question..

I've read in the archives that corvette water pumps use a cast iron impeller that differs from the stamped steel one that is offered by the vendors. My big block 077 pump has a stamped steep impeller so I took a bunch of time to look on the net for a pic of a cast impeller for this pump. I did find many pics of cast impellers from small blocks but none from big blocks. So here's my question... Did bo block pumps really come with a cast iron impeller or not? Specifically a '72 077 pump. A pic wpuld really help to confirm this. Thanks!!

Tom------


They were definitely supplied with a cast iron impeller. In fact, it was once available in SERVICE under GM #3863197. However, it was discontinued without supercession in 1977. It appears pretty much like the small block impeller.

[David L.]

Re: 077 Water pump question..

My 1965-1969 Chevrolet Parts Catalogs (May 1965, Oct. 1965, Oct. 1966, Feb. 1967, April 1967, Oct. 1967, and Oct. 1968) list GM # 3863197 for 1965-1967 Corvettes (396, 427) and is described as "(3 55/64")(stamped 3863197)". GM # 3863197 was discontinued in August 1977 as per GM Parts History.

GM # 3921939 is listed for 1968-1969 ALL, Corvette (396,427). GM # 3921939 was removed from service in June 1971 as per Chevrolet Parts History. My 1972 Corvette Parts Catalog (Sept. 1971) only lists the 3863197 impeller for the 65-67 Corvettes (396.427).

It appears from my parts catalogs that the 3863197 impeller (aka Coolant Pump ROTOR in Gr. 1.109) was only used in 1965-1967 396 & 427 water pumps.

Dave

[Joe L.]

Re: 077 Water pump question..

My 1965-1969 Chevrolet Parts Catalogs (May 1965, Oct. 1965, Oct. 1966, Feb. 1967, April 1967, Oct. 1967, and Oct. 1968) list GM # 3863197 for 1965-1967 Corvettes (396, 427) and is described as "(3 55/64")(stamped 3863197)". GM # 3863197 was discontinued in August 1977 as per GM Parts History.

GM # 3921939 is listed for 1968-1969 ALL, Corvette (396,427). GM # 3921939 was removed from service in June 1971 as per Chevrolet Parts History. My 1972 Corvette Parts Catalog (Sept. 1971) only lists the 3863197 impeller for the 65-67 Corvettes (396.427).

It appears from my parts catalogs that the 3863197 impeller (aka Coolant Pump ROTOR in Gr. 1.109) was only used in 1965-1967 396 & 427 water pumps.

Dave

Dave------


I believe there was very little difference between the 3863197 and the 3921939. For one thing, 1965-67 big block used the exact same waterpump casting as 1968 and some of 1969. Later waterpumps have only very minor differences from the 1965-E69.

[David L.]

Re: 077 Water pump question..

Dave------


I believe there was very little difference between the 3863197 and the 3921939. For one thing, 1965-67 big block used the exact same waterpump casting as 1968 and some of 1969. Later waterpumps have only very minor differences from the 1965-E69.

Joe,

If the 3863197 impeller is cast iron then I would assume that the 3921939 impeller is stamped steel. If the 65-67 BB W/Pump casting is the same as the 68 BB and some 69 BB W/pump castings then I would also assume that the 3921939 could replace a 3863197 impeller. This appears to be a cost savings measure by GM.

Dave

[Tom L.]

Re: 077 Water pump question..

Thanks for all the input. I may be wrong but it appears that there is no direct reference to a cast impeller for the 077 pump OR ANY pump used on a 454. Just my observation since the discussion is directed at 396's and 427's. I did find thiis page (see the attached) from a 2-71 parts book and it doesn't indicate the material used, cast or stamped, for the 3921939 impeller. It only indicates that the 3863197 impeller is stamped not cast.
2-71 parts book.jpg

[Joe L.]

Re: 077 Water pump question..

Joe,

If the 3863197 impeller is cast iron then I would assume that the 3921939 impeller is stamped steel. If the 65-67 BB W/Pump casting is the same as the 68 BB and some 69 BB W/pump castings then I would also assume that the 3921939 could replace a 3863197 impeller. This appears to be a cost savings measure by GM.

Dave

Dave------


It's not stamped steel; it's cast iron. As far as I know, no stamped steel impeller was ever available from GM in SERVICE although they were used in many PRODUCTION waterpumps. I don't even think any stamped steel impellers were being used as early as 1968.

[Joe L.]

Re: 077 Water pump question..

Thanks for all the input. I may be wrong but it appears that there is no direct reference to a cast impeller for the 077 pump OR ANY pump used on a 454. Just my observation since the discussion is directed at 396's and 427's. I did find thiis page (see the attached) from a 2-71 parts book and it doesn't indicate the material used, cast or stamped, for the 3921939 impeller. It only indicates that the 3863197 impeller is stamped not cast.
[ATTACH=CONFIG]51522[/ATTACH]

Tom-----


The 3863197 impeller is not stamped steel. The parts catalog only indicates that it's stamped with the number 3863197. Actually, to be completely accurate, it's not "stamped" with that number; that number is cast into it. However, the parts catalog usually uses the term "stamped" regardless of how the number is applied to a part.