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I know that you addressed the question of whether your water pump is rotating in the correct directions. There are two basic things that a cooling system needs to be effective, adequate air flow and adequate water flow. It sounds like your new fan is pulling enough air to keep the engine cool at idle, but the coolant temp is still rising higher than it should

I hate to say it, but your new 3-pass radiator might not be helping you unless you have a high-flow water pump. Multi-pass (2- or 3-pass) radiators create a restriction in the water flow, so they require a much stronger pump to push enough water through them to work well.

You mentioned in post #7 that you put a new pump on, is it a high-flow design? Also, is your thermostat a high-flow unit, also?

Gerry
 

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Discussion Starter #23
Progress!

So I ran it without the thermostat, and immediatly noticed a drop in coolant levels. I left the cap off and let it purge for a half hour and watched it settle in around 210.

Then I put the thermostat back in. Not like it mattered, at 210 it's open. But I noticed in the dark the headers were glowing. I checked timing with a light and found about 12 degrees. I kept advancing the idle timing until I hit 30 degrees! At that point coolant temp started dropping. Slowly, keeping in mind the thermostat is still open. But It got down to 200. I let it idle for about an hour.

Tomorrow I'm going to drive it and see how it does on the road. Maybe more timing is a big part of the answer. I did put on a new GM reverse flow water pump since the serpentine system is cranking it counter clockwise. I ordered a high flow pump but would rather not install it unless I need to, just because of the mess it will make.

Will report back in a day or two.
 

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One more thing to check. On a system where you have changed pulleys, you might be turning your water pump at the wrong speed. I know a guy who just spent north of $7K trying to solve an overheating problem on a Mercury big block. He had the wrong diameter water pump pulley, and it was underdriving the water pump speed wise. He found out that the correct ratio was either at or close to 1.3 rotations relative to the crank pulley, and that was what water pumps were set up to do. With serpentine systems made to adapt to many engines, you might not have the right ratio. Check this thread:

http://www.pro-touring.com/archive/index.php/t-20497.html
 

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Discussion Starter #25
One more thing to check. On a system where you have changed pulleys, you might be turning your water pump at the wrong speed. I know a guy who just spent north of $7K trying to solve an overheating problem on a Mercury big block. He had the wrong diameter water pump pulley, and it was underdriving the water pump speed wise. He found out that the correct ratio was either at or close to 1.3 rotations relative to the crank pulley, and that was what water pumps were set up to do. With serpentine systems made to adapt to many engines, you might not have the right ratio. Check this thread:

http://www.pro-touring.com/archive/index.php/t-20497.html
I used the GM big block serpentine kit, it included the water pump, pulleys, belt, etc. So I am hoping that they have that all worked out.

I am going to change the water pump tonight for a higher flow one. The overheating is better, but with a huge aluminum 3-pass radiator and giant fan and easy driving it's still warmer than I would like to see.
 

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Are you saying you had 12 initial or 12 total and then moved to 30 initial or 30 total? Because if you have 30 initial and another 18-20 mechanical you're going to be in trouble fast if you hammer on it at all.

You can run 30 degrees at idle between initial and vacuum advance, but you should still be around 34-38 total (initial + mechanical).

If you just rotated the distributor until it ran better, then you likely have too much timing now. You probably already know this, but just wanted to point it out just in case.
 

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Discussion Starter #28
my fitech controls timing, so there's no mechanical advance. So 30 degrees is what it shows on the LCD at idle and I've verified with a timing light. Under power it reverts to a 3x3 table for timing at RPM and load levels.
 

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overheating

read about your trouble with the excess engine heat, my 496 (formerly) 454 overheated as well. tried many of suggested remedies, some meet with a modicum of success. overall - improved the situation somewhat, but did not cure the problem. it wasn't untill I realized after much research that a big, high hp motor makes huge heat too. i finally gave in and installed a custom built (to my specifications) a "Flex-a-lite" dual pass radiator, home built shroud and third fan did i get the overheating problems (regardless of conditions) under control. totally happy with the outcome, i live in so cal. where it can get quite hot but with the new radiator and other heavy duty cooling system components, overheating is no longer an issue. i still have the original spec sheet that i used in my correspondence with flex-a-lite i'd be happy to share it with u, if u want. can't buy direct from flex-a-lite, i went through summit racing, couldn't have been easier.
 

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Discussion Starter #30
A small update. I replaced the GM counter clockwise reverse rotation. Water pump with a high flow one. That dropped Temps just idling by 10 degrees. I added a pusher fan on the front half of the condenser where I could. That helped another 5 degrees. Then I found that the fitech throttle blade was not fully returning to closed causing a high idle. Fixed that and idle dropped from 900to 650. That also helped a few degrees.

I'll do some extended driving this week but it appears a to be a nice improvement at least at idle.
 

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Swapped from a 350 to 454, but now I'm battling overheating. On the big block I am running the Chevy serpentine kit with reverse long water pump. The pump is brand new, so is the engine. It's a GM crate 454.

I have a 180 degree thermostat and an aluminum radiator with a core that's approximately 2" thick by 20" wide. Running two 10" 1000 cfm fans that are pulling the right direction. I have a condenser and trans cooler in front of the radiator but ac is not plumbed up yet.

Car will overheat on a 70 degree day quickly. I watch the Temps Creep past 225 and won't stop. The only way to keep it cool is to jump on the hiway. But at 80mph it still climbs to 195 degrees, where it finally stabilizes.

Thoughts? At first I thought the fans were insufficient, but then at 80mph I would expect much better results even with no fan. I also don't have the inner fenders installed right now, but I wouldn't expect a huge difference from that.
 
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