1964 FI water pump 609 casting ??

[Alan Drake]

Was about to rebuild my water pump from my 1964, L84 "FI" engine, however upon looking at past postings I believe I've got the wrong pump. It must have been replaced pre 1966 before I purchased. Pump has no GM markings or casting numbers on back. It does have on the front "30570" with an "A" under that number, a 10 by the intake from raditor. The rear plate is held on by hex 1/4-20 nuts with washer part of casting and an "E" in the center.

The NCRS Tech Info & Judging Guide appears to say that the 609 pump was for early 63's and from postings that appears to be the present story. SOoo, what is correct for my 1964?

Some facts; 1964 with L84, #113901 and engine assy on Feb 21st. The bypass is 3/4" with a series of diamonds connected vertically with a P logo in the center of each. Yes the 3/4" bypass was used, but all infor says on latter models.
It appears that I will need to find a new pump, but what should I look for?
Thanks for the HELP

[Jack H.]

Re: 1964 FI water pump 609 casting ??

You have a 'generic' water pump (non-GM).... By '64, the correct high horse water pump casting number was 3859326.

When looking for a correct/original pump, bear in mind the same basic casting number was used in other car/truck applications with the difference being Corvette had a SMALL hole drilled/tapped on the upper boss for the external bypass nipple while trucks used a bigger bypass fitting (3/4-inch NPT).

Finding unmolested '609 and '326 water pump housing castings correct for Corvette applications is a little hard (scarce) and you can expect to shell out reasonably big $$$ for one from a catalog source like Goat Hill, Etc....