How to keep sbc 400 from heating up so bad
03-30-2006, 12:33 AM
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How to keep sbc 400 from heating up so bad We have a hopped up sbc 400. It gets hotter then crap. It has the steam holes drilled in the heads. We already blew out one head gasket. any suggestions on how to keep it cool, and not blow out head gaskets. Please let me know. We might just pull the thermestat out and run wide open through the intake without a thermestat. Thanks, Jared
03-30-2006, 12:59 AM
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You may need a bigger radiator and a set of electric fans. You also might want to try this stuff called 40 below (I think that's what its called), but in my experience, this stuff eats up water pumps.
03-30-2006, 05:48 AM
#3
Running without a thermostat may make it run hotter than with the thermostat, as the water flows too fast for heat transfer to take place.
Are you sure the air/fuel is not too lean? Bob
Are you sure the air/fuel is not too lean? Bob
04-02-2006, 10:24 PM
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I have run bored 400s on the street for years. The latest being a 10 sec na motor.
I do not have steam noles drilled, actually they are plugged.
Its imperative you run a T-stat. A good flowing w/p, and a 4 core radiator.
Oh, and the biggest mistake I see......no fan shrouds.
I do not have steam noles drilled, actually they are plugged.
Its imperative you run a T-stat. A good flowing w/p, and a 4 core radiator.
Oh, and the biggest mistake I see......no fan shrouds.
04-20-2006, 07:33 AM
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Yep, must have thermostat and a fan shroud. My 400 never overheated any more than a 305 with the original 305 radiator.
400s don't overheat easier than any other SBC, but they can sustain more damage if allowed to overheat because the steam holes are a common place to initiate cracks. It is in no way a certainty, but not unheard of.
400s don't overheat easier than any other SBC, but they can sustain more damage if allowed to overheat because the steam holes are a common place to initiate cracks. It is in no way a certainty, but not unheard of.
04-20-2006, 09:35 AM
#7
I have often seen people accidentally use the wrong rotation water pump and cause this issue.
The next most popular offender is wrong rotaion fan.
On on 3rd-4th gen F-body's missing front air dams will almost always make a car over heat
Running apumped up 380ci filled half way with Rock and no problems at all here!
The next most popular offender is wrong rotaion fan.
On on 3rd-4th gen F-body's missing front air dams will almost always make a car over heat
Running apumped up 380ci filled half way with Rock and no problems at all here!
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04-20-2006, 06:38 PM
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Originally Posted by 69chevy
Does the fan shroud make a difference if it has a belt driven fan or electric fan?
04-20-2006, 08:56 PM
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I agree with all the info given here all good stuff.
Also look into the trans if you have a high stall converter and no trans cooler (a seperate one) you will run hot. And what exactly is hot? what temp?
Also look into the trans if you have a high stall converter and no trans cooler (a seperate one) you will run hot. And what exactly is hot? what temp?
05-01-2006, 12:18 AM
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just a thought ....
not thinking of money but cooling wise ...
think of this if it`s better or you`ve seen it it might sound crazy hehe ...
a radiator + 2 shrouded elec fans engine side + 2 or more shrouded or not shrouded elec fans on the outside of the radiator
(like those used and cheap fans from different cars and just put as many on the outside hehe
not thinking of money but cooling wise ...
think of this if it`s better or you`ve seen it it might sound crazy hehe ...
a radiator + 2 shrouded elec fans engine side + 2 or more shrouded or not shrouded elec fans on the outside of the radiator
(like those used and cheap fans from different cars and just put as many on the outside hehe
05-07-2006, 03:26 PM
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Timing Try running the vacuum advance to a manifold port (highest at idle). Most mid 70's Chevy vacuum cans are around 6-12* of advance, which is about right. Oldsmobiles used to run hot with a ported vacuum reference and this was a fix for them. The extra timing will turn the heat into power and not put it in the cooling system. Many engines, esp with a bit of cam, like 18-22* at idle. Putting all this into initial lead will cause some spark knock, esp with higher compression ratios. Try 10-12* initial and 10* in the vacuum advance, when you crack the throttle timing backs down a bit. The 406 in my '79 Jimmy (read: Heavy) likes 12* initial and 10* in the vacuum advance, for a total of 32* mechanical and 42* with vacuum. Also, riveting a plate on the water pump impeller (if not already equipped) picks up the flow quite nicely at low speeds. Hope this helps!
05-21-2006, 09:23 PM
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First off, what is the overbore? It's going to be tuff to keep a .40 or .60 over 400 cool on the street. I used a Flow-cooler disc rivited to my stock waterpump which knocked about 5 degrees off. They're like $5 bucks from Summit or Jegs' and they DO work. Also, I would recommend a quality thermostat from Moroso, not one of the Pep Boy's specials. My .40 over motor (350) used to run hot, especially in the summer and when idling at red lights. I put the Flowcooler disc on and a 160 Moroso thermostat and now it goes up to 170, the therm. opens, it drops to 165 and stays there. It's goes up a tad at redlights and on real hot days, but not much. Good luck.
