LS-5 Water Pump Rebuild Kit

**Joe L.** · April 3, 2014, 11:46 PM

Re: LS-5 Water Pump Rebuild Kit

Originally posted by Monte Marin (18651)

I know this is a subject that has been addressed a number of times, but most threads are dealing with small block water pumps or earlier big block water pumps.

That said: Has anybody found a good rebuild kit for the early C-3 big block (LS-5, 3992077, 71-72) water pumps. From what I have gathered, many of the early C-3 big block cars are actually running Chevelle/? style pumps. I know LICS has a good small block kit, but does anyone know anything about a 3/4" kit.

The difference being the early C-3 (LS-5) big block water pumps have the 3/4" shaft and the cast impeller inside, while the Chevelle/Impalla/whatever car, has the 5/8" shaft and the stamped sheet metal impeller. The cast impeller is said to be a higher flowing impeller than the stamped sheet metal one.

I guess it is fairly common for people to put a bushing on the 5/8" shaft to accommodate the 3/4" opening on the fan clutch and pulley. Although this does work, it is not correct for the Corvette.

[ATTACH=CONFIG]52069[/ATTACH] [ATTACH=CONFIG]52070[/ATTACH] This is an original Corvette water pump with 3/4" shaft and four hole flange.[ATTACH=CONFIG]52071[/ATTACH] This pump is the same casting number with a 5/8" shaft and a non-original eight hole flange.

Thanks guys,
Monte

Sorry to run on with information, but I just wanted to stop the people on this forum that like to correct details that have nothing to do with the topic. I hope this keeps this thread on the subject of finding out if there is a good rebuild kit for LS-5 Corvette water pumps.

P.S. Barrowed a few pictures from other members. Thanks

Monte------

ALL big block waterpumps have a 3/4" shaft----every one ever made. However, the shaft I'm talking about is the part that goes through the bearings. ALL 1965-70 Corvette big block waterpumps used a 5/8" PILOT SHAFT (i.e. the portion of the shaft outboard of the waterpump flange). 1971-74 pumps used a full 3/4" PILOT SHAFT.

By the way, the impeller shaft (i.e. the shaft inboard of the bearings and onto which is pressed the impeller) is 5/8" on all big block pumps.

I don't know that any big block waterpumps used in PRODUCTION were originally equipped with stamped steel impellers. It's possible but, if so, I would expect only 1973 or 74. Later GM SERVICE pumps were definitely equipped with stamped steel impellers. Also, pumps that went through commercial rebuilders will also often be found with stamped steel impellers.

I'm very confident that you can obtain an excellent waterpump rebuild kit from Bill Mock

**Monte M.** · April 4, 2014, 01:27 AM

Re: LS-5 Water Pump Rebuild Kit

Joe,
Once again, thanks for clearing up any mis-information I may have had.

I was aware that the impeller side of the shaft was the same on both the pumps with the 5/8" hub shaft and the 3/4" hub shaft. That size being 5/8". I did not know much about the earlier big block water pumps and that is the reason I asked the question the way I did. Being very specific to ask my question about the later big block pump (3992077) that did have the 3/4" shaft (on the hub side).

So, are you saying that the Chevelle big block water pumps had cast impellers as well? Were the stamped steel impeller were most likely service replacements?

And, thank you for filling me in about Bill Mock. I have seen his name around. I will contact him to see what we can do.

Monte

**Joe L.** · April 4, 2014, 04:37 PM

Re: LS-5 Water Pump Rebuild Kit

Originally posted by Monte Marin (18651)

Joe,
Once again, thanks for clearing up any mis-information I may have had.

I was aware that the impeller side of the shaft was the same on both the pumps with the 5/8" hub shaft and the 3/4" hub shaft. That size being 5/8". I did not know much about the earlier big block water pumps and that is the reason I asked the question the way I did. Being very specific to ask my question about the later big block pump (3992077) that did have the 3/4" shaft (on the hub side).

So, are you saying that the Chevelle big block water pumps had cast impellers as well? Were the stamped steel impeller were most likely service replacements?

And, thank you for filling me in about Bill Mock. I have seen his name around. I will contact him to see what we can do.

Monte

Monte------

For 1966-68 Chevelle big blocks used exactly the same waterpump as Corvette big blocks. For 1969+ Chevelles (and most other Chevrolet V-8's too, except Corvette) used the long-leg style waterpumps. As far as I know, all of these were 5/8" pilot waterpumps. Only 71+ Corvette and some MD/HD trucks used waterpumps with 3/4" pilot. This included both big blocks and small blocks.

As far as the impeller goes, I believe that the cast impeller was used through 1974 for both big block Corvettes as well as other Chevrolet big blocks. It is possible, though, that the switch to stamped steel occurred for 1973 or 74. If so, I would expect it would have been for all big block waterpumps, Corvette and otherwise.

LS-5 Water Pump Rebuild Kit

LS-5 Water Pump Rebuild Kit

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