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Discussion Starter #1
Good day,
Looking for some experiencial advise on my engine. BBC gets too hot during idle in traffic but as soon as I get moving and get some air flow through the radiator the temp drops quickly. Also increasing the RPM's somewhat seems to help. My thinking is leading me to the water pump. It's a stock cast pump. What are the advantages of an aluminum pump other than weight?
Thanks
 

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I have a 454 that runs cooler without the water bypass. But I also have a 396 that will over heat without the water bypass hose. Both engines act different in the same truck and with the same cooling system, weird.

Are you using the bypass hose?

Are you using a fan shroud?

What kind of pulleys are you using? stock diameter?

What kind of fan are you using? new fan clutch??
 

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Yes I'm using the bypass hose and fan shroud. The fan clutch is old but I have tried new ones (at least 2) and they did not make a bit of difference. The new ones had less resistance to being spun with my hand when hot then the old one?? again weird. It is the stock 7 blade fan, which is only about 1/2 an inch away from the rad and well inside the shroud.
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Stock pulleys too?

Maybe you should try running without the bypass hose to see what happens. My 454 runs cooler without it. More water passes through the radiator without that bypass hose. But you will need a few 1/8" holes in the T-stat to run without the bypass hose.

Sounds like lack of air or lack of water flow.

Are you using a stock flow water pump?
 

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when a engine heats up at a stop light, of just setting at a idle,, but cools down when moving,,, means that there is not enough air moving through the radiator to dissipate the heat out of the radiator,, either the fan is not pulling enough air , the pump is not pumping enough water a low RPM's,
keep the fan close to the radiator,with a good shroud, covering the whole radiator,,
what temp is the thermostat?
condition of the pump,?
elect or manual pump? electric fans will to pull more air especally a SPAL
Timing correct?
 

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It's a stock cast pump
This would be my first thought... The air flow could be an issue but I`d bet water flow at idle is low... If the engine is above stock which is sounds like it may be...? Then more flow at idle would help for sure... BTW alum is just lighter the design of the impeller and the internal housing make the difference...

One other question...? Is this a short or long pump...?
 

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Is the idle speed set too low

The 454 in my ol' chevy pick-up idles at about 450------heats up in no time at all

Electric fans-----twin 10" on this truck----cool it right off

One of these days I will speed up the idle-----been that low for years

once moving-----won't warm up

Bryan
 

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heat

Ok i am going to take you down another road,,,, I have seen guys spend hundreds of dollars on cooling systems only to find out they never had the correct timing on the engine...

So my question is what is you initial and total timing set at?????


Keith
 

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onovakind67 said:
Maybe you should move the fan away from the radiator until about 1/3 of the blade is out of the shroud.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^that would be the first thing i would try. The whole point in having a shroud is to make the fan pull evenly across the whole radiator not just where the fan is. :thumbup:
 

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Over heating

If your over heating at idle it could be an air, coolant or timing problem. I have the same problem. What size jets are you running. Evans makes an overdrive water pump pulley that should help you at idle,you should also go to Team Chevelle, they have great sit for this.
 

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[QUOTE='69 RS/SS] The fan clutch is old but I have tried new ones (at least 2) and they did not make a bit of difference. The new ones had less resistance to being spun with my hand when hot then the old one?? [/QUOTE]

Get rid of the fan clutch and replace with rigid mounted fan. This will assure that you have air flow at idle.

As has already been suggested; check your timing.

If it is retarded you will run hotter at idle.

Check for vacuum leaks which could attribute to lean idle condition and running hotter.
 

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I don't think an electric fan will pull enough air for a bbc. I had tried that and the stock fan clutch worked much better.

Smaller pulleys will also make it run hot at idle. Use the stock pulleys on a street driven BBC.
 

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Discussion Starter #15
Wow! thanks for all the great suggestions. To answer a few of the questions: I hve adjusted the timing from about 8 degrees to where it is now at about 16 degrees. The same thing was happening at all stages in between? I'm pretty sure that it is the pump as it is quite old--since before the rebuild, and the jetting is quite close to optimum--the plugs look good and runs great.
I think I will ask Santa for a nice aluminum Edelbrock pump this year.
Thank you very much to all that gave their ideas.
Merry Christmas
 
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