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Has anyone came up with an answer to the engines running hot? A friend of mine has two 350`s in two different cars running hot. He says it is ok until he gets up to 60-70 on the highway. I would like to know if this is an on going problem with 350`s that have been bored or what? Can some one do a survey to determine if it is isolated to bored engines, 350`s , crusing or town traffic. Thanks. bowtie-trifive :gba:
 

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This subject has been discussed several times. I have had more than one
350 bored .60 over and never a heating problem. Some things to look at
are radiator, thermostat, water pump, fan and shroud, and high timing.
More than likely the problem lies in one of these areas.
 

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I noticed my stock 283 sbc was getting hot when it was extremely hot/humid in stop start traffic.

I have new rad, thermostate, orig 5 blade steel fan. No shroud.

Once I was up & moving there was no problem :)
 

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5 blade fan, 160* thermostat, alum cross flow radiator but the winner was shroud......problem solved. :anim_25:
:gba:
bowtie-trifive
 

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MY 69 model 300 hp 350 bored .060 without sonic testing runs cool with stock oem radiator, however I have a 4 blade fan and shroud with a 160 stat.
 

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Most engines over heat at low speed or when stopped at idle, usually due to an inadequate cooling system, undersize/restricted radiator, improper air flow/shrouding, etc. Most engines run coolest at higher speeds due to the tremendous amount of available air flow. Sounds like the overheating problems your friend's seeing may be caused by underhood turbulence or excessive RPM's. I would start by looking at the radiator shroud setup.
 

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I'd suspect the radiator.

If the engine won't cool at 70 mph the first thing I'd do would be REPLACE the radiator with a known good high efficiency radiator. And a properly fitted shroud.
 

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If your getting hot at idle or in traffic but it cools back down while moving, its lack of airflow. My first few tri 5s I built in the early 90s would get hot and I tried everything until I went to a high CFM electric fan. Every time I build a street car now, I go electric fan and aluminum radiator. Alot of guys on here run mechanical fans and they work for them. This is just how I fix the problem.
 

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Discussion Starter · #9 ·
Thanks, I wanted to get some information before I lay eyes on the cars. bowtie-trifive :gba:
 

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Very interesting, thanks. bowtie-trifive :gba:
The only issue I did not see addressed was the value of a shroud, especially at low speeds.
 

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You would think it a linear equation...1HP=746 Watts=2545 BTU/h. Well not so easy. Oil weight / type, Coolant type, specific gravity, air flow and air temperature all factor in. IF...You are doing all by the recommended OEM...you can figure what rad will work best. Of course 50 + years later, we aren't.

So...go big or go home is best advice. Large radiator, fan, shroud..you be happy :)
 

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I had a flex fan, that was my overheating problem. Got a fixed 6 blade steel one and problem solved.
 

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First of all, overboring the block does not cause overheating. I guess that myth started with flathead Fords and it may apply to them but not to Chevy engines.

If you have a problem with overheating at highway speed, the first thing I'd look at is the thermostat. It is probably opening but not far enough. A common thermostat failure mode. If it's not the thermostat, I'd be looking at the radiator or water pump.

8 or 9 times out of 10, the thermostat will fix it.
 

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1955 210 SERIES, 406 DUAL QUAD ENGINE WITH MUNCIE 4 SPEED
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Could be that the lower radiator hose is collapsing at high speed . Older hoses had a spring inside to prevent this problem.
 
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