1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

[Mark E.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Ok I wasn't sure of depth, but the concept would have worked, I think.
.......
It's not that difficult to rebuild a water pump given the right kit and a press. I gave up on several rebuilders I've experienced. I had to re-build some "re-built" pumps. Maybe they had a worker or two that were inexperienced, unsure. All I know is what I've had to do over on several occasions. In one case, if I sent it back I'd have missed a judged event.

Both of those vendors mentioned have good reviews.The one other I dealt with had shipped a rebuilt pump with a rusted out bypass neck. It was a challeng to replace it. Another had a wobbly seal due to shoddy workmanship. I'd not have found that problem if I didn't have to pull the backplate to swap it for the correct configuration.
Here.. https://www.forums.ncrs.org/showthre...905#post759905

Rich

I feel your pain, Rich. I sourced a restored pump from one of these water pump vendors with the correct casting numbers for my 454. Apparently too much material was shaved off the mating surfaces because the cover bolts hit the timing cover when installed. After removing and sending back for another casting, the second pump leaked
from the rear cover. The third pump was the charm but it wasn't fun doing this three times.

[Mike T.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Hey Guys - Lotsa conversation on the subject of water pumps, I see. I've been busy too, ordered a replacement water pump from Stewart Industries and a rebuild kit for the 66-vintage water pump that came off the Bigblock in my 66 NOM L72.
First off, to all the folks who made suggestions on who to send it to for a rebuild, thanks, but I think you might have overlooked this one 'underlined' sentence in my original post. I am aware of some businesses who offer rebuilding services, I prefer to do the work myself.
I have sent about 3 sets of main Midyear Gauges to Joe Ray because it's something I can't do myself. And thanks Joe, the last speedo/tach set you went through for me look great and I hope to make the swap into the roadster soon. I feel comfortable rebuilding engines (minus machine work) and the same for steering, trailing arms (with Gary R's technical help, of course), suspension, etc, and rebuilding a water pump is something I would look forward to doing.
Mark Edmondson - I ran across the exact same issue with the two Gates replacement pumps but I can tell you, it's not caused by the vendor surfacing the two surfaces that bolt to the block, it's due to castings being way too thick on the inboard side of those contact surfaces. If it were a case of them surfacing too much off, there's be noticeable pulley misalignment. The only fix is to get out a rotary burr and drum sander and literally shave off around .080 of material along that inboard edge so the pump won't run up on the flange of the timing cover. You'd think that all they had to do was to just use a stock pump as their template but I've run across it twice with overseas pumps.
There is an annual Corvette Club Show here in Prescott every year around late September and I'm trying to wrap up some loose ends so I can drive the 66 BB Roadster to the show. For that reason, and the fact that Corvette Central won't be able to ship that water pump rebuild kit until Sept 16, I decided to buy another replacement pump, this time from a fairly well known outfit, Stewart Components. It arrived yesterday and I just had to look inside so off came the rear cover. Check out the three pics, one is of the original 66 pump, the next one is the Gates version and last is the Stewart. I did contact Stewart and asked them about any issues with casting size interfering with the timing cover and they 'said' they hadn't heard any complaints. The clearance between the 66 and Gates pump impellers to pump body was about .080, give or take. The gap between the Stewart impeller was under .020 and notice the actual diameter of the impellors. I expect there should be good flow from this pump.
Okay, so now for the update on my overheating issue and there were two smoking guns. The engine ran fairly smooth but slowly would get hot, enough to hear coolant bubbling in the radiator and it came out the overflow hose. The temps verified with an IR gun showed it was warm but not overly high, the temp after running for at least 20 minutes was up around 190. I also found, after shutting the engine off, fuel percolating out of the rear bowl and into the venturies. On that particular issue, the float level was a bit high so lowered it but that didn't stop it. I was trying to figure out how this was happening if the temps were under 200 or so. Looked down and noticed the heat riser and the weighted arm was 'up' and this was with the engine stabilized at 190 and had run for the 20 or so minutes. Pushed it downward and it moved freely but as soon as I moved the long screwdriver away...it popped back up obviously pushing hot exhaust back up through the intake and over to the drivers side, superheating the fuel in the bowls. So, for now I wired it open and that problem seems to be solved.
Back to the engine overheating and remember I've had this Corvette for about 2 months but have only put about 30 or so miles on it so there's quite a bit of discovery going on here. The radiator tubes looked good, new thermostat, now new water pump due to the original dated pump leaking out the lower weep hole and new heater core, so why would it be bubbling up when the temps were not cresting 200+? Dug out my radiator cap pressure tester and...voila, what looked to be a nearly new or at least fresh, radiator cap...wasn't holding any pressure. Replaced it with a cap I got from my local Chevy Dealer back about a dozen years ago, tested it and it holds 15/16 pound no problem. Still putting the distributor back together so can't test drive it but expect things will be much better than before.
IMG_9013.jpgIMG_9018.jpgIMG_9051.jpgIMG_9054.jpgIMG_9061.jpg

[Gary J.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Save time and give Bill Mock a call about water pumps. His knowledge runs deep and he can help you anytime! His number can be found in the For Sale Ads here on the board!


JR

Agree with JR. I have bought several correct water pumps from Bill Mock and had several rebuilt by him over the years. Never any problems with his pumps. Bill Mock advertises in the Driveline.

[Mark E.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Mike,

You share an interesting case se study of more than one failure causing a problem. Good job of methodically running down the root causes.

Your original impeller has 8 vanes vs. 6 for the others. How does this affect things?

Didn't some/many water pumps of this vintage have cast impellers? Not a leading question; I just want to know.

Regarding the too short water pump that interfered with the timing cover: Removing material wouldnot fix this. It needed more material for clearance. Triple gaskets may have worked in a pinch...

[Mike T.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Mark - Thanks, it's been interesting to say the least. In the 'old days' we'd head to the local Parts House, buy a pump, bolt it up and move on smartly. Not so much anymore, it seems.
I can't really say if the 8-vane original pump was any more efficient because I probably put a grand total of '5' miles on it before tearing into things.
As for the cast versus stamped impellers, that's been bugging me since I opened up the back of the 66-vintage 3868284 pump. I was expecting to find a cast impeller but saw this 8 vane version instead. The body-off was done in the early 90's and the previous owner said the original 427 was long gone when he bought it in late 80's. The exhaust manifolds, intake manifold, service replacement #3247 carb were still on there and I was sorta surprised to find a 66 dated water pump but there was an odd sound out of it (during the brief 5 mile run) and after removing the pulley and belts, I saw the telltale lower weep hole stain. Now knowing the radiator cap was defective, I think the old pump, even with it's large .080 clearances between vanes and pump body was probably still mostly functional. From what I've been able to gather, after reading old threads such as Rich Mozzettas, even if I was able to dig up a cast impellor, I couldn't use it since the available rebuild kits use a main shaft that is about .004 or so thinner. So, we're stuck with what we have, stamped impellers. But, they aren't all the same, as the Stewart Pump shows.
I've got a few more pics to post that will show what I meant by the wider than necessary pump contact surfaces. There are '4' pics, 2 showing the 'stiffener' cast into the 66 vintage pump body and you can see it doesn't extend down to the contact surface (mating surface) of the pump but check out the 2 pics of the Gates pump and you can see that cast-in stiffener (for lack of a better descriptor) does extend down to the contact surface. I have a loose BB timing cover and used it to grind down the inside edge of the pumps...both of the offshore pumps to get them to clear that raised timing cover flange. 1966 Pump Stiffener Stops Short of Contact Surface Pic Looking Down.jpg1966 Pump Stiffener Stops Short of Mating Surface Side Shot.jpgGates Pump Stiffener Extends Down to Contact Surface and Pic Taken After I Ground Down Inside Ed.jpgGates Pump Stiffener Extends to Contact Surface and Pic is After I Ground Down the Inside Edge.jpg

[Richard M.]

Re: 1966 Bigblock - Replacement Water Pumps or Rebuild Kits?

Mike, LIC used to sell a kit(21-39D) but it was just the bearing and seal, no impeller or hub, so that may be the SAE sized non-metric shaft size. Likely for original cast impeller & hub.

But since your cast impeller is gone, someone likely rebuilt your pump in the recent past using the stamped impeller kit. May have come with the 8 hole hub too?

CC has a complete kit but n/a until 9-16, as I think you said somewhere.

Since you want to get this back together I would drive the main bearing down 0.015"- 0.021" to get the impeller blades clearance back in spec and move on. The hub will be down/in a few thousandths which will probably be negligible for now.

Then you can hunt for a older type cast impeller kit later. I may have a cast kit back in FL but won't be back there for a few months. I know I have 2 or 3 cast SB new kits I got from John Meisinger about 5 years ago, but unsure if I have one of his BB kits on the shelves. Next time my grandson goes over to cut the grass I'll have him look.

Rich