H20 Pump question for 70 C3

[Travis Williamson]

I recently purchased a water pump with the casting #3782608. According to the NCRS judging manual this is the correct casting number for the small block motor.

The pump that is coming off now is not original but has a casting #3880175 (I think that is the number but it has a lot of rust so some of the numbers are hard to make out). Im not sure where this pump came from as my dad had it installed many years ago.

I just wanted to make sure that the 3782608 is the correct pump for a L-46 with A/C before I installed it.

thanks

[Terry M.]

Re: H20 Pump question for 70 C3

All 1970 Corvette small blocks, regardless of options, used the same water pump -- #608

[Jack H.]

Two sources though....

The '608 water pump housing was cast both in Saginaw as well as Tonawanda and a number of suppliers don't distinguish. Corvette SB engines were built in Flint with Saginaw supplied castings, so a Tonawanda cast '608 pump would technically be incorrect for your car.

Check the housing for a floating 'T' emboss (typically near the casting number) indicating Tonawanda as the source and check the casting date's year code (Tonawanda used two digit dates on water pumps while Saginaw used a single digit).

[Terry M.]

Good point Jack, also....

I don't know if the 608 pump was used on early 1971 engines, or if the 1971 pump showed up on late 1970 engines. If one had a late 1970 Corvette some research on that issue would be in order.

[mike mccagh]

Re: Good point Jack, also....

terry and jack: when it comes to midyear H20 pumps , the tonowanda castings have a gusset cast into the drivers side front wall whereas the sag's lack the gussett, suspect the same is true of the c-3 pumps. mike

[mike mccagh]

Re: Good point Jack, also....

PS; i should have included the c-1's with the c-2's in the previous post. sorrry. mike

[Joe L.]

Re: H20 Pump question for 70 C3

Travis-----

As others have described, the 3782608 is the correct waterpump casting for your application. There was no GM #3880175 waterpump casting. However, there was a GM #3839175, which may be what you actually have. This pump was used on some 1963 and 1964 Corvettes and is a rather uncommon casting. It has an external bypass fitting on the top which, if original, will be drilled and tapped for 1/2" NPT and would require plugging for your application. The 3782608 casting has no provisions for external bypass and the top of the casting, therefore, has no large boss.

[Jack H.]

Not always true, Mike....

I've seen quite a few '493 pumps (57-60) cast in Tonawanda and all HAD the reinforcing gussets you mention on the front LH leg. But, I've NEVER seen a 608 water pump with that reinforcing 'feature'. I've seen a LOT of '608 pumps cast both in Saginaw and Tonawanda and I only see two differences:

(1) The Saginaw castings generally have their source code (a RAISED 'S') emboss but it's on the back side of the pump. The same Tonawanda castings lack this but have a recessed 'T' generally in the viscinity of the casting number/mold ID.

(2) Saginaw castings (when dated) have the casting date embossed on the front LH leg (single digit year code). Tonawanda '608 castings position the date either there OR in a horizontal plane on the lower front face just to the RH side of the shaft and use a 2-digit year code.

Also, I bumped into a '55-56E '911 water pump a couple of weeks ago (no upper boss for external bypass) and it had a LARGE, depressed 'T' just below the casting number emboss.