494 RB water pump pulley options

The story at the top, question at the bottom.

Two weeks ago I got a Cuda with an odd "overheating" problem.

I bought it from a guy near Eau Claire, drove 350 miles home... 10.5:1 494 RB, Quick Flow 950, Victor 440, Performer RPM heads, 268° solid cam, 4 speed, 3.73 dana, 295/65/15 rear tires...

On the interstate it stays at 180 F @ 50 mph, 60 mph, 70 mph, 80+ mph.

Cruising on back roads at 30-40 mph it stays at 180 F.

"Spirited" driving up to 7500 rpm it stays at 180 F.

Idling 1-2 minutes it stays at 180 F... then the mechanical coolant temp gauge starts to "twitch" from 180 to 210...

Turn off the engine after idling 1-2 minutes and the temp gauge continues to "twitch" from 180-210 F and you can hear it boiling in the pass rear head...

Wait 5 minutes and you can remove the radiator cap and it does not push out any water.

No coolant in oil, compression 150-155 psi on all cylinders, plugs all look normal.

Pressure test cooling system to 15 psi it will hold for hours...

Play with ignition timing from 30 - 38 degrees total... no change

Drill three 1/16 holes in 180° thermostat ... no change

Change from 16 psi cap to 7 psi cap to 13 psi cap... no change

Change to 160° thermostat... same behavior, just runs at 160° instead of 180°.

drill two 1/8 holes in 160° thermostat... takes longer to get to 160, but no change.

Currently has a "AC Delco / Rock Auto" 6 blade stamped steel impeller water pump with the a flat metal "anti-cav" plate on the back, it has over 0.100" clearance between the blades and the proflo aluminum housing

Crank pulley is 6.5" diameter
Water pump pulley is 6.75" diameter

I am ordering a flowkooler 16 blade pump, but also want to OD the water pump 10-20%

Where can I buy a 5.5 to 6.0 diameter water pump pulley for a non-A/C RB Mopar?

Thanks

Craig

What is the fan set up, not enough air flow at idle !!!!

the fact that it works fine while driving says not enough air flow throuigh the radiator at idle. Do you have a fan shroud installed?

Yes, it has a typical champion aluminum radiator with a shroud. The engine temp does not slowly climb at idle, it jumps up and down. I am quite sure the flow from the water pump drops off too much at idle due to excess clearance between the blades and the housing...as a result the coolant in the back of the pass side head basically stops... it develops a local hot spot that boils the coolant. The system holds several gallons of coolant, if the issue was airflow, it would take more time to overheat.

Ok , so what happens when sitting if you bring the RPM up 2, 3 hundred ?

If it were mine, I would fix/reduce that 0.100" clearance first.

How large is the by pass hole under the thermostat in the water pump housing? Most are too large and will allow too much hot block water into the cooled water stream and cause some weird stuff to happen. Especially at low engine speed. Drill and tap that hole for a brass pipe plug. Then drill a small hole in the plug. Test drives will determine the end size needed. You can remove the thermostat and reach in to drill the plug without too much trouble.

But the hole can't be too small either. It allows the thermostat to 'see' some hot block water and keep it's operation consistent.

Motor home thermostats originally had a plunger on the bottom of their thermostats that would cover that hole when the thermostat opened up.

Above 1500 rpm seems fine.

I missed this part .100 on the blades, I agree with Russ on fixing this 1st,

I also did what Dave is saying & YES it helped, I have a .050 hole in mine, it took a lot of tricks to keep my 512, with A/C running cool down here in Southeast Texas, 180ish all day long

Well, my flowkooler 16 vane pump is on its way...

If it works well I will probably abandon my attempt to get a 15% OD water pump pulley setup... If it does not work a good friend of mine has suggested we build a water pump dyno... I hope it does not come to that...

I have the Flowcooler pump on my car and it moves a lot of coolant at idle. I have the 440 Source stock type 1 to 1 pulleys and a 7 blade viscous fan on my 493 with a little under 600 HP and it runs cool with a stock type pulley and fan setup. It has a 26" ECP radiator without a shroud.

Gus

Craig,

There was an extensive water pump comparison, look at this thread on dodgecharger.com, from 2009.

http://www.dodgecharger.com/forum/index.php/topic,60599.175.html

17 page thread, the comparison starts on about page 7.

I saw it, very interesting results. Not intuitive that straight vanes would have such a big advantage at low speed

Just FYI. The clearance between the FlowKooler 16 vane impeller and the ProFlow housing is over 0.100 inch but it does seem to flow enough to prevent the boiling issue in the back of the pass. side head. I am changing the cam and will be having the ProFlo housing cut down about 0.050 inch to reduce the clearance.

Craig

when you cut down the housing to reduce the vane clearance, will you be adding a shim behind the water pump pulley to make up for what you cut, or will you move the pulley mount forward on the pump shaft to do so ?