[george kujanski]

Lee, what you need is a cast vane pump with the proper vane height. 1/2" of clearance is more than just somebody's mistake. No way was that much clearance OEM. I'll bet that "adjusting" the divider plate is not/will not be a total solution for you. No one should have to accept a hot Pontiac. Contact one of the other members in this thread, they could help a brother out and get a pump for you if you can't find one.

George

[getmygoat]

I've got some additional data to share...

This past weekend, I truly became a "GTO freak" as the girlfriend says!..

I bought the long pump at NAPA (55-975) then I found a place that rebuilds pumps, (sandiegowaterpumps.com) and had them switch the nice new NAPA impeller to my "short" pump casting.. I gave them my backing plate, and they were actually able to adjust the position of the impeller to sit closer to the backing plate! (He didn't press it all the way onto the shaft)

The guy there says that the rebuilders all set the impellers way off the backing plate because they don't want to worry about hitting the backing plate and being liable for it! So they are intentionally hurting the cooling system of our Pontiacs to save their liability! Of course, this all stems from the faulty design, in that the impeller clearance can't be pre-set by the rebuilder (as it can in most pumps).

Anyway, now the results... No joy! After spending over $230 in water pumps! (Yes, no kidding)... I took the '69 "up the hill" east out of San Diego.. now it was a pretty stressful test (85 mph, with the A/C on ).. but she hit 230 about 20 miles into it - RATS..

So, I've got a "blueprinted" water pump, 160 thermostat, timing is good... I'm out of ideas.

Fred

[buwalda]

In conjunction with this thread, there is some excellent cooling info on the
www.stewartcomponents.com
website, under Tech Tips or Tech Info.
Many Old Wives Tales, like 'slowing the water down' & 'double pass' radiator advantage are put to rest.

[george kujanski]

Fred, review your setup for us...there has to be a solution. Now that the water pump is correct, let's take a look at the rest of your setup.

Hey, just to make sure you're not chasing ghosts, is your intrumentation telling you the truth?

George

[jafuzz1]

Yea, my problem has always been hot at idle. I couldn't even go to the cruise nights because she would be almost pegged once driving to the parking spot, and then the old faithfull out the overflow hose. The divider plates from Ames didn't fit the best into the good used timing cover, so I modified them slightly to fit the passages tighter, then after tweaking the plates to the impeller, I had to tweak them to stay flat around the perimeter as well. I'm also wondering if the pumps with the taller vanes are tapered from the middle out, 'cause my plate is only close in the middle at the opening now, but will still be the same wide gap at the outer edges. Do you think that would have anything to do with it? More info on my setup, the engine is stock, besides a .30 overbore and a 068 cam. I'm Running fanclutch with sevenblade fan, and an A/C shroud. I thought about the seals for the shroud, but the A/C cars had a taller radiator, and I wasn't sure if they would install into my shorter setup.

[george kujanski]

Malky would be a more informed source on the diver plate-to-vane fit issue, but I would think ideally the fit SHOULD be close along the vane length. This may be hard to do in practice on an aftermarket pump, however.

Your temps were always hot at idle? Going back to basics again, timing, (vacuum advance), flow restriction someplace, (clogged radiator or block water passages) not enuf airflow thru the rad (fan clutch issue). Too large water pump pulley?

If it's ok at higher speeds, your airflow thru the rad is better than at idle (fan clutch bad)and you have more coolant flow due to higher pump speed.

Eliminate the basic problems one at a time. Open the rad cap once the tstat opens & see if you have good flow.

George

[Old Goat 67]

Fred, In response to your question; "I'm also wondering if the pumps with the taller vanes are tapered from the middle out, 'cause my plate is only close in the middle at the opening now, but will still be the same wide gap at the outer edges." , see below picture I made of my 67 pump with the old plate, you can see the fit of the vanes with the plate because of the configuration of the 67 plate with it's cutout for inlet water. If the vanes do not fit the plate all of the vane's configuration, I think you will get a good deal of cavitation (turbulence) which will be detrimental to overall pump operation, therefore "flow". Just my two cents.....
Charles

[jafuzz1]

Actually flow seems to be awesome now. All else is brand new...4 core rad (also had roded at rad shop for that reason) fan is new, clutch is new, pulley is original, but I always thought it was plenty big. Timing was low 'till last Sat. Now I timed it with a vac gauge. I need to pull a plug yet to see about my fuel mixtures.

[jafuzz1]

That's a great picture. For some reason I believe I threw away my original plates ('cause I can't find them) and I just did it last fall. I returned my original waterpump as a core back in '97 or so. Now I wish I would've saved all that stuff. Maybe my Lemans 326 still has the original pump. I'll have to check that out.

[getmygoat]

George,

My setup is pretty standard..rebuilt 400/350 (about 1500 miles on the rebuild), w/ a NAPA impeller, 160 stat, new heavy duty fan clutch, newish 4-row radiator, good timing... A couple possibilities:

1) I havn't dialed in the carb, but the way the car pollutes, I doubt its running lean!
2) I havn't double checked the advances (mechanical and vacumm).. The distributor is stock, but its got one of those "hidden" electronic conversions that eliminates points... That was on the car when I bought it and I havn't messed with it.
3) This makes me sound stupid, but the coolant level is low.. there's about 20 vertical rows of those little "spouts" showing when I look down into the hot, running coolant.. The problem is that in '69, GTO's didn't come with an overflow tank, so when I fill it up, it just burps out the coolant down to that level. I suppose I could add an overflow tank, but that would be bad for originality.

What's the highest probability at this point?

Thanks,
Fred

P.S. - I couldn't really rev the motor to test coolent flow, those 3-chamber Flowmasters are too loud, didn't want to wake my boring neigbors at 11PM.. but I don't know how it would be possible to get those vanes any closer.. I messed with that backing plate for two hours...Its true what OldGoat67 mentioned about the vanes sloping off towards the outer diameter.. but the backing plate just doesn't have the same contour, so it would be tough to have tight clearances across the entire impeller diameter, me thinks?

[george kujanski]

Fred, you've got to have the proper amount of coolant. Without an modern "closed" system, the recommendation was to fill to 1" below the filler neck to allow for expansion.

A four-row radiator? there's got to be some BIG issue with your setup to still be heating. That's just wrong. Take care of the coolant level issue; check for good flow at idle with the thermostat open. You should see good flow at idle, per OLDGOAT67. Make sure your vacuum advance is working.

Another thing I've thought of, especially with aftermarket radiators. On some late-model cars I've seen, the engine head and thermostat housing are actually higher than the top of the radiator. This may lead to trapped air in the engine, even when the radiator is supposedly full. It happens on my driver, and the manual specifies the proper fill procedure when filling the radiator.

Just another thing to check.

George

[Rugratman]

O.K. guy's, I pulled the water pump, off my GTO. The pump that was on there was a cast pump, However the vanes start about an inch away from the center of the impeller. See attched pic. I ordered a new water pump from Parts America from one of the first couple of pages of the topic, a link really. They sent me a new water pump, unfortunatly it a 8 bolt pump, not a 11 bolt. The vanes on the impellors are much longer and start more at the center of the impeller. My car is heating up at idel, with no end in site, moving down the road, she will run 185 with a rodney red. Timing is correct, new block. My question is: is the cast impeller that I have good enough? And where can I get the correct 11 bolt pump? I read earlier that Napa has them, I need that part number, They only had stamped impellers this morning.
I will enclose a pic of the old pump and the new pump with the vanes. I was thinking that by closing the gap on the plate, with no vanes in the center of the impeller, it might not flow as well, I want to post some pic's for you guy's and your expert suggestions.
Thanks in advance.

[Rugratman]

crappy pic sorry

[Rugratman]

new pump / wrong size.

[jafuzz1]

The impeller on your last picture looks identicle to the one on my reman (1st pump) from NAPA...right down to the part number. The other pictures look like a stamped impeller??
GetmyGoat, quick question...what psi rad cap are you running, and is it any good?

[george kujanski]

ON your 11 bolt pump: I believe the important thing on vane placement is that the vanes start, with minimum clearances, at the eye of the divider plate inlet. As long as the inside diameter of the vanes starts at the inlet hole and continue outward to the edge of the impeller wheel, you can't ask for more. Malky is the most knowledgeable on pump design so he may chime in, or read his posts in the above thread for more info.

Can you take a non-fuzzed side view pic of your existing 11 bolt?

I've also noticed on the pix that the 8 bolt cast pumps have 6 vanes vs. eight on 11 bolt pumps. I wonder.....can a 11 bolt impeller be pressed on a 8 bolt pump for an efficiency improvement? Is the wheel diameter the same?

George

[Rugratman]

hope this shot is better.

[Rugratman]

another

[kate`s67gto]

I bought a new pump from Napa in jan. on the receipt it ihas p671 for part number.This is a 11 bolt pump. It is a reman. cast impeller. They had to search their warehouse for one with cast impeller. It works great with the backing plate tweeked. No overheating issues at all now, 160 stat Rodney Red rad. 18" cadillac fan with heavy duty clutch. This is with a rebuilt engine 160 on hiway and 170 in town , may have to go to 180 stat. It is such a pleasure driving and not watching the temp guage.

[GR8ONE68]

Fred and Old Goat 67,

Go back to page 16 of this thread. I posted pictures of my new/used Napa water pump. This was a factory piece that was rebuilt, it has the pontiac numbers cast into it. It does not appear that the vane were tapered on the water pump that I got.

Kevin