Water pump for 1964 327/250

[Gerard S.]

I have removed the water pump from my 1964 Corvette 327/250 and want to replace it with the proper pump. I have owned this car for 16 years. I believe the pump I removed is not the original. It has 4 markings in the cast: 1. it has a "T", 2. it has "GM 11", 3. it has "3782608' and 4. it has "H2663". This pump has no bypass hose in the casting which I believe is correct for that engine in that year. However, as I read through other postings it appears that the "T" is a Tonawanda casting and those were never part of origianal assembly. Also, this pump has reinforcing ribs in the casting located on the drivers side which I believe is also incorrect.

I would like confirmation that the replacement pump should have a casting number of 3782608, no bypass hose and no ribs. Are there any other markings I should be aware of to ensure I replace with the correct pump? Any thoughts on a reliable place to purchase the new pump?

Thank you for your help!

[Joe L.]

Re: Water pump for 1964 327/250

I have removed the water pump from my 1964 Corvette 327/250 and want to replace it with the proper pump. I have owned this car for 16 years. I believe the pump I removed is not the original. It has 4 markings in the cast: 1. it has a "T", 2. it has "GM 11", 3. it has "3782608' and 4. it has "H2663". This pump has no bypass hose in the casting which I believe is correct for that engine in that year. However, as I read through other postings it appears that the "T" is a Tonawanda casting and those were never part of origianal assembly. Also, this pump has reinforcing ribs in the casting located on the drivers side which I believe is also incorrect.

I would like confirmation that the replacement pump should have a casting number of 3782608, no bypass hose and no ribs. Are there any other markings I should be aware of to ensure I replace with the correct pump? Any thoughts on a reliable place to purchase the new pump?

Thank you for your help!

Gerard-----


Yes, a "T" casting mark, the 2 digit year date code, as well as the ribs indicate a Tonawanda casting. Supposedly, these were not used on Corvettes. However, depending upon when your 1964 was built, this pump could have a date-correct code. That might imply it is original. On the other hand, it could also be that some previous owner sought out and installed a date-correct pump without realizing that a Tonawanda-cast pump would not be considered correct. Plus, unless your car is very low original mileage, it's doubtful that it would still have its original waterpump. These old 5/8" shaft pumps usually have a life of about 50,000 miles.

To have a pump that would be considered correct you do need a 3782608 casting and without the ribs or "T" casting mark. Dating for the '608' pump started in the spring of 1964. So, depending upon when your engine was assembled, you may need a pump without or with a date code.

The 3782608 pump casting is anything but rare. They were used on the vast majority of Chevrolet small blocks from 1961 to 1968 so there are lots of examples out there. Bill Mock, who advertises in the Driveline, is a waterpump specialist and would be an excellent source for a correct and properly rebuilt pump.

[Gerard S.]

Re: Water pump for 1964 327/250

Joe,
Thanks for your detailed response, very helpful.

[Joe L.]

Re: Water pump for 1964 327/250

Joe,
Thanks for your detailed response, very helpful.

Gerard-----

By the way, if you find a pump that appears to have the 3782608 casting number but has a top bypass fitting, that pump is actually a 3782609 (an "8" and a "9" can be extremely difficult to discern with respect to casting numbers) make absolutely sure that you buy it. You could trade it for about 50 completely rebuilt '608' pumps + extra money.

[Dale M.]

Re: Water pump for 1964 327/250

Joe, I have a March 16th engine build date. Does anyone know if my water pump should have a date code or not? Since I have aout 120K miles I assume it been changed out.

[Mike M.]

Re: Water pump for 1964 327/250

if one finds a 609 that is drilled and tapped for the 90 degree bypass fitting, make sure its tapped for 1/2" pipe plug( there are 609 pumps out there that are drilled for 3/4" pipe plugs and will need an adaptor to accept the 90 degree fitting). the judges look for the presence of the adaptor and deduct accordingly. agree with joe that the correctly drilled and tapped 609 is worth what 50 of the 608's will bring.mike

[Joe L.]

Re: Water pump for 1964 327/250

Joe, I have a March 16th engine build date. Does anyone know if my water pump should have a date code or not? Since I have aout 120K miles I assume it been changed out.

Dale-----

That's just about the exact time that pump dating began. If you could find a pump with a date that works for the engine, use it. However, I think that if you just used a non-dated one no one is going to argue with that given the engine build date. I don't even know if waterpump dates are judged.

[John H.]

Re: Water pump for 1964 327/250

Dale -

Most water pump date codes aren't visible with the pulley installed.