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Hey guys - I am doing some work on cooling. Replacing the water pump and radiator. I am aware of the mod to tighten up the space between the back divider plate and the impeller, but I read about another mod that I wanted to get your opinion on too. My understanding is that the middle divider plate is best positioned directly in the middle of the impeller, as I understand it, so flowing water can be equally proportioned on either side of the divider, which then goes to the left and right side of the block. I took out my pump and this middle divider was flush to the impeller. So I am wondering if I modify the middle plate to sit at middle of the impeller I would be doing myself a favor. Have you guys heard of this? agree or not?
 

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That plate is supposed to just touch the impeller without the gasket so it sounds like yours has the proper clearance.
My car set up like this with a 195 thermostat runs at 195 and as high as 210 if I really romp on it but comes back down rather quickly to 195 when I cruise it.
I have tried different thermostats but my engine runs best at 195.
 

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Thanks gr. Are you referring to the back divider?

I was looking at both dividers again and it does seem to make sense that the middle plate should straddle the impeller to split the flow to each hole into the block....
 

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There should be just two plates, front and back.
Support the pump casting on a couple of blocks and peen the front plate until it barely touches the impeller.
Put the gasket on then the plate and spin it, if it doesn't touch you are there.
Too far back and the coolant cavitates decreasing the flow.
Back plate should be flat.
Mine had the back plate missing so I bought a repop set made of stainless.
 

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Thanks gr. Are you referring to the back divider?

I was looking at both dividers again and it does seem to make sense that the middle plate should straddle the impeller to split the flow to each hole into the block....
You would be correct. Mine is set up exactly like that. Very perceptive
 

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Discussion Starter #7
Cool. I just got it back in the car. Will finish this weekend and report how it goes. New cold case radiator, flowkooler pump with the divider mods, and 160 Tstat. I am expecting the car to make ice cubes when it’s all said and done. Only thing left is electric fan but was not ready to give up clutch fan yet.
 

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no need to give up clutch fan, as long as your clutch is working right it will cool as good as the electric and i suspect with the 160 TS and correct mods it will stick at 175 on the worst days, mine does. Also a correctly sized and mounted fan shroud is a must, fan blades centered to the edge of the shroud.
 

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Ok here is an update. Super happy. Around town I was probably running 200 on a 75 degree day. Sitting at idle for 15 minutes also put me at 200. While it is a bit cooler outside, I am now running at 160 pretty solidly. Stomping on it a lot might get me to 170 but no higher. And it drops back to 160 pretty quickly. I have not got out on highway yet, but previously at 2300 rpm or so I was at 220ish. I suspect I will never see more than 180. Will update.

I did not get to take pics after my mods, but here is the before below. What you see is the original middle plate laying flat on original pump. Note how it’s flush to the impeller. Not good. Using the same middle plate on the blue flowkooler (before modifying) The flowkooler impeller is less flush, which is better, but it was still not straddling the impeller equidistant. So what you dont see is where peened the edge of this plate to where it straddles the impeller equally.

I also did the mod that seems to be more known- where the back divider plate is peened inward to tighten the clearance to the top of the impeller.

So that’s my story. Snowcones for everyone!
 

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Discussion Starter #12
Also just to remind this is an 8 bolt water pump. They come with two divider plates. I think it’s the case that the 11 bolt water pump that came later only has one divider plate.
 
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