73 Water Pump Question (SB w/AC)

[Jeffrey N.]

Old water pump.jpgNew water pump.jpg

Thanks!

[Floyd B.]

Re: 73 Water Pump Question (SB w/AC)

I don't know the answer, but I do notice in your pictures that the rim at the mounting surfaces is noticeably thicker on the new pump. The new pump appears to be about 1/4" and the old pump looks to be about 1/8". Perhaps the old pump had been rebuilt at some point? The mounting surfaces on these pumps can become rusted and pitted. Some people prefer to fill the pitted surface with epoxy but perhaps a rebuilder machined the surface, thus removing material.

[Patrick H.]

Re: 73 Water Pump Question (SB w/AC)

Do the other holes exhibit the same depth problem as the one you show?

What is the casting number of the pump you removed?
Is the “new” water pump a reproduction, or another 330813 modified to appear correct on your car? The 330813 itself is not uncommon.

[Jeffrey N.]

Re: 73 Water Pump Question (SB w/AC)

Thanks for your feedback and additional questions..

No, the other mounting hole (for the AC Compressor Support Bracket) is the same depth as the "old" water pump.

The casting number on the "old" pump I removed is G 31. It's not a original 330813 casting - I wish it was. The AC Compressor Support Bracket mounts up to this old water pump without problems.

The "new" water pump is a reproduction I bought from Paragon. It seems like the mounting pad I'm having trouble with wasn't milled down deep enough, but I'm not sure. That's why I was hoping someone may know what the dimensions should be or have a GM drawing for the mounting pads.
If I had access to a machine shop, the quick solution would be to mill it down. But not knowing the depth it should be could cause a problem somewhere else.

I bought the reproduction water pump to get the car going, drive it for a while and determine if there are other things that needed replacement. My longer term goal is to go through the car and make it as original as I can.

Maybe my solution to this problem is to find the proper 330813 casting and have it rebuilt and ditch the reproduction pump.

[Eric P.]

Re: 73 Water Pump Question (SB w/AC)

Jeffrey,
There are a couple of NCRS members who sell original water pumps, so I don not want to exclude anyone or say one is better. I have a 1973 L82 with A\C and needed a correct water pump myself. I found the correct replacement from ChevyCool. The water pump they delivered was a perfect fit, painted and ready to install. You will find their advertisement on page 23 in the November-December NCRS Driveline.

Eric Patty
NCRS #8355

[Larry M.]

Re: 73 Water Pump Question (SB w/AC)

1. Having existing pump rebuilt. Arthur Gould or Chevy Cool or ?? can do this very easily.

2. Buy a rebuilt original #330813 pump from Chevy Cool

Your choice..........

Larry

[Jeffrey N.]

Re: 73 Water Pump Question (SB w/AC)

Thanks! I'll check the Driveline.

[John S.]

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[Jeffrey N.]

Re: 73 Water Pump Question (SB w/AC)

John,
Thank you! This is exactly what I needed to confirm my issue with the reproduction pump.
So now I'm on the hunt for a 330813 water pump with a "C" date code. My engine build date is 04/04/73. I've talked to Chevy Cool and he doesn't have one but is looking.
I purchased my car last fall and am just getting into it. It's been a great winter diversion during COVID.
Jeff

[John S.]