72 Lt1 water pump

[James G.]

I am going to be changing my timing gears and chain, oil pan gaskets, timing chain cover gaskets and seal. I would like to replace the water pump which was changed at some point before I owned the car. My question is, where can I get a good picture of an original pump for my car? I would like to match the casting as I am not to worried about date coding being that the car is a driver.

[Patrick H.]

Re: 72 Lt1 water pump

I am going to be changing my timing gears and chain, oil pan gaskets, timing chain cover gaskets and seal. I would like to replace the water pump which was changed at some point before I owned the car. My question is, where can I get a good picture of an original pump for my car? I would like to match the casting as I am not to worried about date coding being that the car is a driver.

James,

How "early" or late is your car?
"Early" cars supposedly took the 3991399 and "late" (after S/N 22 000) took 330813.
Both pumps are not easy to find with the correct onfiguration. The 399 is a one-and-a-half-year-only item, and the 813 without a "bypass" drilled into the top is also not common. As I understand it the 813 with a bypass was used for a while after 1972. However, if your car already has a water pump with a bypass then it really doesn't matter as it still isn't appearing "right."

Patrick

[Jack H.]

Re: 72 Lt1 water pump

Amen to what Pat says about 3991399 pumps being rather scarce. One small comment, the JG actually reads on the transition from 3991399 to 330813 as being:

"After sometime in June (after about s/n 22,000 or so)...."

Notice the TRIPLE disclaimer as to the effective cut over ('after', 'about', and 'or so')... That's telling you we really don't know a crisp definition of 'early' and 'late' in this regard. Plus, things would have been further confused by what inventory was on-hand at the Flint Engine plant when the change was made. So, I'd cut owners of June/July built cars a HEALTHY degree of slack on this one...

Personally, I've seen '399 pumps date coded both May and June which tells me they were still casting the housings this late into the '72 model year...

[James G.]

Re: 72 Lt1 water pump

My cars engine pad is a May 12 build date with the letter V being the first character stamped in the pad. The water pump that is on the car now has a threaded boss on top of the pump.

[Patrick H.]

Re: 72 Lt1 water pump

My cars engine pad is a May 12 build date with the letter V being the first character stamped in the pad. The water pump that is on the car now has a threaded boss on top of the pump.

That's very similar to mine, #22917. My replacement water pump has the same configuration. I've been on the waiting list for a 330813 for almost a year now. So, I know they're not easy to find without the threaded boss.

[James G.]

Re: 72 Lt1 water pump

Pat, am I to assume the stock pump should not have the threaded boss? Also the numbers you mentioned for the pump is that a part no. or casting no. You have to excuse my number knowledge as most of my car is original so I never really became to involved with them.

[Roy V.]

Re: 72 Lt1 water pump






James, I know the photo of the water pump doesn't show the boss we have been refering to, but, if you look to the right you can see the threaded plug that would be screwed into the top of the water pump.
My car is a July 13 build with the vin ending in 26154, my water pump is original to the car and has not been tapped to accept that plug.
Brad Maynard ran an ad on the CF that no one replied to back on 3/7/09 and he had a 330813 water pump for sale he was asking $40 and his number is 317 432-4198 ( he is also a NCRS member). Hope this helps
Roy

[Patrick H.]

Re: 72 Lt1 water pump

Brad Maynard ran an ad on the CF that no one replied to back on 3/7/09 and he had a 330813 water pump for sale he was asking $40 and his number is 317 432-4198 ( he is also a NCRS member). Hope this helps
Roy

Realize that later 330813s did have the boss drilled and tapped so you cannot go by casting number alone. So, even at $40 it may not be of the right configuration and therefore no better than the "wrong" casting number. Brad's ad notes later dates so I suspect they are not correct for a 72.

Patrick

[Joe L.]

Re: 72 Lt1 water pump

That's very similar to mine, #22917. My replacement water pump has the same configuration. I've been on the waiting list for a 330813 for almost a year now. So, I know they're not easy to find without the threaded boss.

Patrick-----


Yes, the 330813 castings without the tapping in the boss are quite rare. They were only used for a very short period of time and only on Corvettes (MD/HD trucks used the casting WITH the tapping which soon thereafter became the standard for both Corvettes and such trucks).

However, I really do not think it would be that difficult to "convert" a tapped casting to a non-tapped one. Simply install an internal hex pipe plug and turn it down so that the top is below the level of the top of the boss. Fill the void with JB Weld or other filler, grind flush, and paint with the engine. Done. Of course, one still might have a "date" problem, but one won't have a configuration problem.

[Brad M.]

Re: 72 Lt1 water pump

I have never really checked for the threaded boss/plug on the 330813s that I have, but would bet that these do have the threaded plug as you guys indicate. One of mine is dated in march 73 and the other is dated in 75 - I will try to dig them out this weekend.

[Joe L.]

Re: 72 Lt1 water pump

I have never really checked for the threaded boss/plug on the 330813s that I have, but would bet that these do have the threaded plug as you guys indicate. One of mine is dated in march 73 and the other is dated in 75 - I will try to dig them out this weekend.

Brad-----


I'd be very surprised if 330813 castings dated 1973 and 1975 did not have the tappings in the upper boss.

[Patrick H.]

Re: 72 Lt1 water pump

Brad-----


I'd be very surprised if 330813 castings dated 1973 and 1975 did not have the tappings in the upper boss.

Ditto.
If they aren't tapped I'll take one.

[Paul C.]

Re: 72 Lt1 water pump

I have a Jan 1971 built LT-1. I can't see the numbers on the water pump because they are covered up by the pulleys and I don't want to take it apart to find out now. How do the judges know if it is the correct one if they can't see the numbers--which is the position I'm in. I'm not sure about the boss you are talking about but mine doesn't have any hole or plug in the top, has the reinforcing ribs, and has GM on the drivers side of the pump and the casting date H140 which would be August 14, 1970--which would agree with my build date. From this information can I assume it is a 3991399--if not how can I confirm this. The build date on
Paul

[Patrick H.]

Re: 72 Lt1 water pump

I have a Jan 1971 built LT-1. I can't see the numbers on the water pump because they are covered up by the pulleys and I don't want to take it apart to find out now. How do the judges know if it is the correct one if they can't see the numbers--which is the position I'm in. I'm not sure about the boss you are talking about but mine doesn't have any hole or plug in the top, has the reinforcing ribs, and has GM on the drivers side of the pump and the casting date H140 which would be August 14, 1970--which would agree with my build date. From this information can I assume it is a 3991399--if not how can I confirm this. The build date on
Paul

Paul,

Below note the picture of my 72 with its replacement water pump. The boss and threaded insert aren't exactly subtle. My 71 has the correct 399 pump and the bump that's present on top of the water pump is far smaller than what you see here. I think you will agree.

Patrick

[James G.]

Re: 72 Lt1 water pump

Joe Lucias idea to convert a tapped pump to a correct casting sounds simple enough but you brought up a good point about the size of the boss that is tapped vs. the correct pump boss size. Is there any way to measure this?