[Hotrodjohn71]

Hi group, I've got a question about the water pump divider plates in my 1965 Pontiac 326 engine. The inner divider plate with the round hole appears to be cast while the other plate appears to be steel.
I'm having wide clearance issues between the impeller and the divider plate and I'm wanting to bend the plate so the clearance is very tight but I don't want to break what appears to be a cast divider plate. Does this sound right?
I realized that my pump is a junk stamped steel impeller China version. I have a Flow cooler pump on the way

[george kujanski]

Looks cast. Don't mess with it. IMO try pulling the impeller back on the shaft a bit instead.

George

[John V.]

Not an expert at all, but I believe that cast piece was original in '64/'65.

But I believe it is cast aluminum like the '64/'65 Timing Chain Cover, some of which were also produced by CFD (I think might have been "Central Foundry Division of GM?) while other TCCs I believe were made by a company with the name or trademark "Diecast".

I suspect your clearance problem is mostly a function of the stamped steel impeller. I have an original '64 water pump with cast impeller which I had rebuilt. Original restored radiator. No shroud (no A/C either) and aftermarket fan clutch with an original late production (so not original to my early GTO build, original early '64 fans were steel) 18" dia. aluminum fan. And if anything, my rebuilt 389 runs a lot cooler than I expected it would.

Seems like when this has been discussed here in the past, the solution is to adjust the stamped steel impeller placement on the shaft or better is to get a pump that retains the cast iron impeller.

You might try a search on this forum.

You might want to read this thread from the beginning.

Not sure you want to hammer on the cast aluminum internal housing to close up the clearance. I'm thinking all those that hammered on the housing to reduce clearance were dealing with a stamped steel housing, Moving the impeller would seem a better idea in the case of a cast housing.

But I'm just guessing, never had to adjust mine.

https://forums.maxperformanceinc.com...d.php?t=411256

[60sstuff]

My Original ‘65 GTO (build 11A) only had the single water pump cast plate.

It did not have a second metal divider plate. The “dual divider plates” were first used in 1966.

My photos are a little grainy, but you can see how the Factory unit was assembled.

The outer lip of the cast plate mates with the inside of the water pump.
Very little clearance between the plate and the impellers.

I needed to replace the bearing on my pump shortly after in bought the car.

It runs efficiently and cool as designed.

[Hotrodjohn71]

Thanks guys. I'm now on page 7 of 56 of the thread link that John shared and am learning alot.
60sstuff, thank you for sharing the images. That's my setup right there.
I think I will wait to see what kind of gap I have with the Flowkooler pump (coming soon).
Since my impeller plate is cast and I cannot bend it (if necessary) I guess I could order a set of stainless steel plates from Butler.

I will keep reading the thread John shared.

[John V.]

Chris, that doesn't seem right. Starting in '63 with the change to the aluminum Timing Chain Cover at mid year, all V8s thru '65 were supposed to get the 9773375 cast aluminum Internal Housing and the 9773373 Divider. The early '63 pump and Timing Chain Cover was different so would not have this setup.

Not sure why your '65 would have been missing the Divider. I believe if you check the '64 or '65 Shop Manual it will show both the Internal Housing and the separate Divider.

For sure, the MPC lists them.

I have no idea how coolant pumping would have been affected by a missing Divider.

I'm heading off to an appointment but will check my Shop Manual when I return. But my '64 had the two pieces when I replaced it in '73 (can't be sure it was an original but some reason to believe it was) and I have always understood all of the 8 bolt pumps used the Internal Housing plus Divider until the advent of the 11 bolt pump. I think the '66 up Internal Housing may have been stamped steel rather than diecast aluminum but the concept did not change AFAIK.

[60sstuff]

My Bad. Getting forgetful.

John,
You are correct!

Hotrodjohn71,
Sorry about my confusing reply.

Photos below should clarify.

1965 shop manual illustration showing internal housing with metal divider.
MPC part numbers.
2014 photo showing my cast plate with metal divider plate in my timing chain cover.
NOS Metal divider plates for later year.

Regards, Chris

[John V.]

Interesting that the '67 MPC dropped the original cast aluminum Internal Housing p/n 9773375 and replaced it with the Package 9777445 which was shown in the '66 MPC and included an Internal Housing and a Divider as a set.

Yet they continued to list the separate '63-'65 Divider p/n 9773373 as an individually serviced part!

Your NOS 9793131 Package superseded the 9777445 Package, I believe your p/n was first used in '69. But not sure when the 9777445 was superseded, could have been in '69 or perhaps some time later. But eventually was the only way to service the Housing and Divider for an 8 bolt pump application.

Rechecking the '66 MPC, I see that the 9777445 Package was listed for the '64-'66, not the '66 only that I first thought when doing a quick check earlier today.

Can't be sure, but I now think the 9777445 Package included the cast aluminum Housing 9773375 and the stamped steel Divider 9773373. The Package was just a convenient way to order both parts.

No idea when the stamped steel Housing was first used in production, maybe '68? Or perhaps it was introduced for Service only after the end of '68 production so that all 8 bolt pumps used in production may have used the 9773375 cast Housing?

The timing isn't really important to this thread.

What I think is important, Hotrodjohn71, is the clearance needed. Hopefully the Flowkooler pump will have the clearance it should to the cast aluminum Housing.

If it doesn't, you might find that an original pump with factory cast iron impeller and rebuilt by a competent rebuilder would give you the best performance and match the cast Housing you have.

'Ol Pinion head on this forum rebuilds pumps, you might try a PM to him to see if he has something for you. There are several 9772716 pumps on eBay right now but be sure you get the tall vane V8 pump and not the shorter vane 4 cyl pump that used the same 9772716 pump body casting.