[MarkS57]

Just went through an update of my 8 bolt timing cover in the midst of a cam swap. I went with a FlowKooler pump back when I did the engine install into my 65 in 2015. At the time, I wasn't up to speed on the divider plate issues. Now, it seemed like a Gates pump with its cast iron impeller was a good bet. So I ditched the FK and ordered a Gates from Rock Auto. Well boys & girls, the Gates pump no longer has a cast impeller. If this is old news, sorry about that. The one I got from Rock has a stamped steel impeller. And the impeller fins are about a half mile from the divider plate. So, the Gates is going back to Rock and I modified the plates to work with the FK. Pretty easy to get a tight fit to the impeller on the 1st plate and was able to modify the 2nd plate to split the water flow fairly equal.

Also put a restrictor in the bypass. It was over 1/2" in diameter to start, now down to 5/16". Is that large enough??

Thanks,

Mark

[tom s]

I found no diff when I put the 8 bolt FK on my car over a stock cast iron impeller factory pump.Tom

[dataway]

I see the specs for the Gates pump on Rock is still saying cast iron, they need to change that.

Looks like they are now offering a rebuilt service for original pumps. Evidently they send them to Cardone to be rebuilt.

[MarkS57]

The 8 bolt cover with the FK pump, modified divider plates & bypass restrictor are producing rock solid temps in the engine. Temp goes to 180 deg and that's it, stays there, no matter what. Never saw it that solid before.

Rock hasn't change the Gates description yet. Even the Gates website quotes a stamped sheet metal impeller.

[PONTIAC LARRY]

Originally Posted by dataway

I see the specs for the Gates pump on Rock is still saying cast iron, they need to change that.

Looks like they are now offering a rebuilt service for original pumps. Evidently they send them to Cardone to be rebuilt.

I bought the top Gates 8 bolt on Rockauto last year and it was cast iron with nice looking cast iron impeller

[PONTIAC LARRY]

Originally Posted by PONTIAC LARRY

I bought the top Gates 8 bolt on Rockauto last year and it was cast iron with nice looking cast iron impeller

I also was still having weird heat creeping up thing in our 66 Starchief 389 after this and several high flow 160 and 180 Robert Shaw T stats both vintage NOS and new and already had the Summit racing aluminum $500 radiator with factory steel AC fan shroud and HD clutch fan that had been replaced recently. Block had been flushed and clean and flow was good. After that I did a new Flowcooler 8 bolt from Summit with pretty blue alum imp and only saw minimal improvement but would still start overheating slowly creaping up after a while .. totally infuriating as I never had issues with 8 bolt cars in the past. Finally the random thought of going to a oem power flex fan I had from a 68 400 Firebird. Put that one and it totally fixed it 100% stays on T Stat !

[MarkS57]

Originally Posted by MarkS57

The 8 bolt cover with the FK pump, modified divider plates & bypass restrictor are producing rock solid temps in the engine. Temp goes to 180 deg and that's it, stays there, no matter what. Never saw it that solid before.

Rock hasn't change the Gates description yet. Even the Gates website quotes a stamped sheet metal impeller.

OK, so now the Gates website is back to saying the 8 bolt 43122 pump has a cast iron impeller where as 3-4 weeks ago they it had it down as a stamped steel impeller and that is exactly what I got from Rock.

[lust4speed]

Missed this earlier. I drill and tap for a pipe plug to reduce the enlarged bypass hole and drill a 1/4" hole through the plug. That's enough to recirculate coolant for winter and the smaller hole keeps most of the coolant going through the radiator and not shortcutting back through the engine.

I also have never seen a difference between cast iron and stamped steel impellers for cooling ability.

[MarkS57]

Originally Posted by lust4speed

Missed this earlier. I drill and tap for a pipe plug to reduce the enlarged bypass hole and drill a 1/4" hole through the plug. That's enough to recirculate coolant for winter and the smaller hole keeps most of the coolant going through the radiator and not shortcutting back through the engine.

I also have never seen a difference between cast iron and stamped steel impellers for cooling ability.

Thanks for the reply. I went with 5/16" on the hole in the pipe plug (mostly because the plug had a 5/16" hex key). These restrictors seem to work very well and a great mod for any Pontiac V8.

I honestly think re-contouring the divider plates makes the biggest difference. Keeping the Flow Cooler pump required less bending / shaping of the plates compared to the stamped steel impeller; the gap with un-modified plates was excessive with the stamped impeller.

[leeklm]

When you guys mention "bypass", I assume you are referring to the outlet from head to the heater core hose?

Sent from my SM-G965U using Tapatalk

[lust4speed]

No. Bypass is the passage from the top of the timing cover (water pump area) to the coolant crossover that has the thermostat and the return hose to the radiator.

In the included photo I installed the restriction in the timing cover, but it can go into either the timing cover or crossover. In this case the timing cover was badly eroded and the hole was huge. As long as I was working on the cover I installed the drilled plug. You can still see the outline of the hole after years of erosion that was filled and then drilled and tapped for the plug.

[leeklm]

Thank you for the clarification, I have not yet tried that modification!

Sent from my SM-G965U using Tapatalk

[Half-Inch Stud]

I just ordered 2 Aluminum water Pumps from Partsgeek for $48 each.

[dataway]

HIS ... post pics, didn't even know there was such a thing.