airbournein2001
Forum Newbie
Posts: 67
Loc: central ms
Reg: 06-28-12
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06-28-12 05:59 PM - Post#2242384
Hello all,
New to the forum and looking for some insight or ideas. I know this subject has been beat to death, but it looks as if I have tried all the tips. I am now looking for some new one's. I have a 55 chevy Delray coupe with a sbc 400. Cam dynamics 280/480, .30 over, stock heads, headers, new flowcooler high flow water pump with matching 160 tstat, new alluminum 3 core (stock size) radiator. Complete new fuel system from the tank to the carb. Timing is set great. custom fit an alluminum fan shroud with the 6 blade flexfan half in and half out. Fan sits about 2 in from radiator. head/intake gaskets intact. pump pulley appears to be right size.
Car runs about 160-170 when above 30 miles an hour, but after a few traffic lights and stop signs running around town, it slowly creeps up. I usually find a resting spot when i hit the 205 degree mark. not real sure how high it would go, but have a good feeling it will continue up.
I am wondering if I went to a bigger radiator, if it would help? I have a 16' elec fan with relay kit to mount as a pusher, think that will help?? im near the end of ideas. Just short of pulling the engine and replacing it with one that has a better history for cooling. But I really like the sound and the torque.
one more thing to add....the points are a bit worn and will be replacing them with a new pertronix electronic (under cap) module with a new coil. will this have any effect?
| Kick the tire light the fire! 55' Delray Club Coupe, a family icon for 40 years. |
Edited by airbournein2001 on 06-28-12 06:20 PM. Reason for edit: No reason given.
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 62chevy427
"7th Year" Silver Supporting Member
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06-28-12 06:30 PM - Post#2242399
In response to airbournein2001
in town,will it cool off when you rev it up some? sounds like you are not getting enough air flow.how big is your fan? can you go bigger and maybe go to a smaller pump pulley or a larger engine pulley to make the fan/pump turn faster. you might try a different fan. the pusher fan will probably help in town.
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bobb
Super Senior Member
Posts: 4626
Loc: paradise
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06-28-12 11:23 PM - Post#2242473
In response to airbournein2001
got pics?
| 70 L camino 350 all forged,174 baby blower, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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sgian
Valued Contributor
Posts: 4438
Loc: MO
Reg: 12-25-03
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06-29-12 03:52 AM - Post#2242498
In response to bobb
Flex fans can kill you when they fail, that is why the major automakers stopped using them in the 70's. However, that is not the overheating problem.
Stock temp is 195* F. At 160*, it is too cold and you are increasing the cylinder wall wear unnecessarily. I wouldn't be concerned until it got over 210*.
Running hot under 30 mph is usually an air flow or coolant flow issue, but it sounds to me like you have it all set up good. You might benefit from a radiator that has more surface area, but you would probably have to do some mods. What's the surface area of the radiator core? You probably already know it is length times width of the core area to find the result.
Last thought, are the heads specifically for a 400? Or are they heads designed for a 350? 400 heads have more coolant holes drilled in them.
| 04 Silverado Z71, 10 Cobalt |
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 wagonmaster
Moderator
Posts: 8006
Age: 64
Loc: Loganville, Ga.
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06-29-12 04:51 AM - Post#2242516
In response to sgian
Sounds like you need more fan if it's good over 30 mph....I use an electric in my '39 because it's too close for a mechanical unit. Never an idle/traffic issue with my 6.0 LQ9/4L80E....
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models916
Frequent Contributor
Posts: 1872
Age: 62
Loc: Addison, IL
Reg: 05-28-10
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06-29-12 05:25 AM - Post#2242532
In response to airbournein2001
Use a SBF water pump pulley for added flow. Cools down most minor overheats.
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airbournein2001
Forum Newbie
Posts: 67
Loc: central ms
Reg: 06-28-12
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06-29-12 09:20 AM - Post#2242605
In response to wagonmaster
Thanks guys, The flexfan is a 16in as well as the electric fan. The funny thing is...After i installed the new pump, tstat,and shroud, I took it for a test drive. It was about 60deg outside. The car ran bearutifully for about 45 min. A little cold down the highway (160-170) but perfect (180-190) at idle. Three days later when the OAT hit 100 here is central ms, I took it for another drive at that's when she started acting up. down the highway 180 deg rock solid, slow down for more than 15-20 min, needle creeps up.
My gut tells me I don't have enough surface area in the radiator, but would rather Try something cheaper before I have to fabricate a new front end to house a larger radiator.
It has the transmission cooler in the lower section. How much cooling capacity is that robbing? enough to make a difference in the engine?
I have several pics on my phone, but no way to tranfer them. I am also working in the Gulf with no way to get any and post them
The pulley and fan will be cheaper than a radiator. You guys think an extra inch willmake a difference? I can also look into getting a smaller pulley too.
man...I worked hard 10 hr days for three days fitting and molding and making brackets for that shroud. If I change fans..it will start all over. Oh well, you do what you have to, right!
| Kick the tire light the fire! 55' Delray Club Coupe, a family icon for 40 years. |
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65_Impala
Very Senior Member
Posts: 1593
Reg: 12-29-02
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07-02-12 09:21 PM - Post#2243825
In response to airbournein2001
Try with it idling at say 1000rpm and see if it cools then. If so, that's pointing to too little coolant flow and/or too little airflow.
Is this shroud sealed to the rad so all the air the fan pulls must flow through the rad?
You have enough rad because it will cool >30mpg so you just need to figure out how to get the coolant and air flowing enough at the lower speeds and rpm's.
Double check the tuning too. I believe not enough timing or too lean will both cause extra engine heating.
Edited by 65_Impala on 07-02-12 09:22 PM. Reason for edit: No reason given.
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gchemist
Senior Chevytalk Moderator
Posts: 20826
Loc: Austin, TX 78748
Reg: 05-09-00
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07-03-12 04:15 AM - Post#2243891
In response to 65_Impala
Upgrade to a Stewart water pump.
http://www.stewartcomponents.com/
Ditch the flex fan. Upgrade to a Mark VIII or LS1 dual fan setup. I run a dual fan LS1 setup in my truck.
Mark VIII fan upgrade
http://www.off-road.com/trucks-4x4/project/pr oject...
http://www.fordmuscle.com/archives/2003/02/elec tri...
'83 Silverardo XST - ZZ4 powered
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D.Mac
Senior Member
Posts: 969
Loc: Ontario Canada
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07-03-12 05:03 AM - Post#2243905
In response to gchemist
Make sure that the hot air from the back of the rad is not circulating back over the top of the rad support to the front and being re-used by the fans. Found this to be the proplem once after alot of troubleshooting on a custom set-up.
Dave MacDonald
Ontario, Canada
'66 Impala LT1/C950-,EFI,700R4,(sold 07/2011)
'12 Sonic LTZ, Turbo, M6
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FleetsideLarry
Member
Posts: 547
Age: 68
Loc: Shellman Bluff, Coastal G...
Reg: 01-08-03
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07-03-12 06:22 AM - Post#2243930
In response to airbournein2001
....You guys think an extra inch will make a difference?
the area of a 16 in diameter circle is roughly 200 in², the area of a 17 in diameter circle is over 226. that's a 13% increase. but, I think that if the the fan shroud is sealed-off properly and the fan positioned correctly in the shroud and close to the radiator, the diameter might not be such a big deal.
can you run a clutch type fan? I have a flexfan, it hangs on the wall in my garage.
how about trying a 180° thermostat (on the theory that the 160 is flowing too much for the radiator to have time to cool the coolant) I know that last sounds off-the-wall (and maybe is, I'll hear about it if so  ), but I'm assuming that a 160 thermostat not only opens at a lower temp it also allows more coolant to flow than, say, a 180.
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models916
Frequent Contributor
Posts: 1872
Age: 62
Loc: Addison, IL
Reg: 05-28-10
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07-03-12 02:45 PM - Post#2244096
In response to FleetsideLarry
Wrong. Nearly everywhere.
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65_Impala
Very Senior Member
Posts: 1593
Reg: 12-29-02
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07-03-12 03:03 PM - Post#2244102
In response to FleetsideLarry
how about trying a 180° thermostat (on the theory that the 160 is flowing too much for the radiator to have time to cool the coolant) I know that last sounds off-the-wall (and maybe is, I'll hear about it if so ), but I'm assuming that a 160 thermostat not only opens at a lower temp it also allows more coolant to flow than, say, a 180.
No no no no no no no no no no no. More flow = more cooling!!!!
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FleetsideLarry
Member
Posts: 547
Age: 68
Loc: Shellman Bluff, Coastal G...
Reg: 01-08-03
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07-03-12 04:24 PM - Post#2244120
In response to models916
Wrong. Nearly everywhere.
 see, I told you.
but, models916, for clarification, what do you mean "nearly everywhere". like, do you mean it's wrong to say that a 17 in fan covers 13% more area than a 16? or, if the shroud is built/sealed properly and the fan is positioned correctly, the 16 will be nearly as effective as the 17? or that if you flow coolant too fast through a radiator it WON'T have time to cool. or that it is possible that a 160° thermostat flows more coolant than a 180?
I'm not upset that you're saying I'm wrong, far from it, I'd just like to know how more specifically
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models916
Frequent Contributor
Posts: 1872
Age: 62
Loc: Addison, IL
Reg: 05-28-10
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07-03-12 05:32 PM - Post#2244154
In response to FleetsideLarry
Yep, nearly all of it.
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bobb
Super Senior Member
Posts: 4626
Loc: paradise
Reg: 09-05-03
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07-03-12 08:56 PM - Post#2244248
In response to models916
i guess we need more clarification....
| 70 L camino 350 all forged,174 baby blower, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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mike beck
Contributor
Posts: 218
Reg: 05-20-10
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07-03-12 09:26 PM - Post#2244256
In response to bobb
Have you tried Evans Coolant to see if it helps you?
Is this a stock 400 build? IE: Short rods? Correct heads and head gaskets? IE: Steam holes in the heads and gaskets?
I always use a 5.7 or 6 inch rod when doing 406's, the short rod engines always run hot.
Dual electric fans will be better than your single fan, if you can fit them.
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bobb
Super Senior Member
Posts: 4626
Loc: paradise
Reg: 09-05-03
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07-03-12 10:25 PM - Post#2244272
In response to mike beck
thats interesting. any theory on why short rod engines run hot. i have a shortrod 377 that i was thinking about redoing.
| 70 L camino 350 all forged,174 baby blower, g-force 5 spd, road rage suspension. Pray first before all else fails. |
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busterrm
Contributor
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07-03-12 11:16 PM - Post#2244285
In response to bobb
thats interesting. any theory on why short rod engines run hot. i have a shortrod 377 that i was thinking about redoing.
bobb, they put more side load on the cylinders, more friction, equates to more heat.
==== BOB ====
If I can't smoke the tires I want more!
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models916
Frequent Contributor
Posts: 1872
Age: 62
Loc: Addison, IL
Reg: 05-28-10
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07-05-12 05:43 AM - Post#2244660
In response to busterrm
Here is an example. 16 inch fan with 5 inch long blades and 12 pitch is better than a 17 with 4 inch blaces. Or the same with more or less pitch. Or 7 blade 16 vs 17 with 5 blades. It's all so wrong to make blanket statements about something like 16 vs 17. This is a more technical situation than just 17 is bigger than 16.
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FleetsideLarry
Member
Posts: 547
Age: 68
Loc: Shellman Bluff, Coastal G...
Reg: 01-08-03
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07-05-12 06:01 AM - Post#2244662
In response to models916
thanks, models916. yes I certainly over-simplified the comparison by neglecting blade pitch/size.
Edited by FleetsideLarry on 07-05-12 06:03 AM. Reason for edit: No reason given.
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obibob
Forum Newbie
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Loc: Flint, MI
Reg: 04-25-10
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07-07-12 08:41 AM - Post#2245385
In response to airbournein2001
Howdy, I have a sb 400, had to deal with all the same things you are. Here's what I did; first find a comparble sized clutch fan in GREAT condition flex fans are called that for a reason and if you need to pull alot of air they can flex and lose pitch, switch to a 180 t'stat (even a 195 high flow wouldn't be out of order)and a good water pump (I've had great performance from a Stewart pump)....Make sure your belts are not slipping under a load (had this problem when I was in the chrome everything phase) Make sure there's a clear path for air flow in and out. if you use the electric fan as a pusher set it up so the blades spin in the opposite direction as the engine fan( this creates shear which make light turbulence which helps the air carry away a little more heat) this is in a '55, are the side panels on the core support? a short seal across the top of the core support could help reduce hot air flowing back over the rad. A good presure cap on the rad helps too. Lastly remember a 400 will want to run about 200 degrees most of the time, that's ok, don't worry until it hits 230, don't over-cool it either, this will make it hard to tune. The trans. cooler will not cause any overheat problems. the quickest way to find out if you need more radiator is to turn on the heater, if the temp drops significantly, you need more rad. Also make sure you have the spring in the lower rad. hose, this keeps it from collapsing if you have a good water pump drawing alot through it..also when the engine was built , did the heads have the steanm holes in them to match the block - at the proper angle - just drilling the holes straight through the head surface will cause problems - the angle has to match the block..with a 400 there's alot of little things that work to make the whole better. I had to do all these things at one point until I found the right formula for my Chevelle
Contrary to popular belief, speed doesn’t kill, accuracy does. Ain’t that right Osama?
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 1956cpe
"8th Year" Gold Supporting Member
Posts: 823
Loc: Carlsbad, CA
Reg: 07-07-04
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07-07-12 04:01 PM - Post#2245516
In response to airbournein2001
I have been following your post to see what suggestions come up. Is it possible your engine is running a little lean on the idle side?
The reason I ask is that I have a built 400 sbc and it never runs hot. Actually, most of the time too cool.
I have a Ron Davis alum. cross flow rad and a manual trans, fan shroud with 16 inch flex fan, Eddy water pump 180 t-stat.Most days in traffic it will just get to 180. On cool mornings it will run about 160.
Like you, trying to figure out the mysteries.
pete
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 dcairns
"4th Year" Silver Supporting Member
Posts: 1530
Loc: Orange CA
Reg: 11-07-03
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07-07-12 06:55 PM - Post#2245554
In response to 1956cpe
Sorry if this is a stupid question, but Isn't 205 degrees a valid operating temperature? And isn't 160-170 a bit too low?
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1956cpe
"8th Year" Gold Supporting Member
Posts: 823
Loc: Carlsbad, CA
Reg: 07-07-04
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07-07-12 08:20 PM - Post#2245565
In response to dcairns
Dave,
Not a stupid question at all. And I agree, 205 is probably in a safe range and 160-170 is low and not affording complete combustion.
I'm going out on the proverbial limb here and suggest that a perfect operating temp for an SBC is about 195 deg. This guess on my part is listening to advice from people over the years that know much more than I do.
From what I have read and learned new LS generation motors like to run in the 210 deg. zone.
Pete
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Willys36
Contributor
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07-09-12 02:11 PM - Post#2246196
In response to 1956cpe
In my expeerience just about every cooling problem is due to poor air flow. If the water side was a problem it was due to a failed thermostat or borken pump. Otherwise it's always a problem w/ air flow.
Your temps don't sound like a problem to me. Running too cold causes all kinds of problems so you want to be +200F most of the time. Intil you reach 212F your system will be running at atmospheric pressure + some pressure increase due to fluid expansion and the backpressure held by your cap rating. Modern smog engines are designed o run @ 265F for pollution control reasons. The engine will run fine at that temperature and heat rejection by the radiator is actually improved at higher temps. If you have a good modern radiator and 7psi cap you can run 230F without 'boiling over'. If you run a 15psi cap (good radiator too!), you can go up to 250F without boiling problems.
Running 200F to 210F should be no problem for any engine.
“We can't solve problems by using the same kind of thinking we used when we created them.”
Albert Einstein |
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65_Impala
Very Senior Member
Posts: 1593
Reg: 12-29-02
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07-09-12 09:04 PM - Post#2246405
In response to Willys36
Hmm, now I want to know which engines run at 265*F???? Is that with a thermostat rated somewhere around 250*F????
Electric fans are ususally set with a on-off switching band at a temp higher than the full-open thermostat temps plus some margin. This means engines with electric fans tend to see a higher temp swing. An engine with 2-speed fans has 2 on-off switching bands above the thermostat full-open temps which makes for an even larger temp swing. That's just the way the OEM's do it to keep it simple and cheap.
GM is quite happy with the thermostat and rad allowing the LS1 to run in the mid 190's on the highway. So, you can't really argue that the LS1 engine runs best or is designed to run in 210-220 range when the installed thermostat keeps it in the mid 190's. They just end up at a higher temp in city driving while waiting for the fans to start working.
What the engine really wants is cold air and hot oil. The moving bits needs to be in the right temp range so they have the correct clearances. Al parts are more dependent on this since the thermal expansion co-efficent of Al is about 2x that of iron. Still, the clearance differences between the engine parts at 160* or 190* won't make enough difference to matter.
Edited by 65_Impala on 07-09-12 09:07 PM. Reason for edit: No reason given.
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Mike73
Senior Member
Posts: 710
Loc: Ontario, Canada
Reg: 01-31-00
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07-09-12 09:11 PM - Post#2246409
In response to 65_Impala
I'd check top tank and bottom tank rad temps when it over heats.
If the temps are close to the same, e.g. top tank 230, bottom 220, you have an airflow issue. You aren't expelling the heat.
If the top is 230 and the bottom is 160, you have a water flow issue (the coolant spending too much time in the rad, therefore big temp drop)
low tech way to do this is simply grab the lower rad hose. If you can keep your hand on it without getting quickly scalded, it's 160 or less.
73 Laguna Coupe 400/400
Bayliner with a 229CID Chevy V6 |
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Willys36
Contributor
Posts: 495
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Loc: Bakersfield CA
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07-10-12 03:25 PM - Post#2246703
In response to 65_Impala
Check your steam tables; 15psig cap will not pop-off until water temp is 250F. Late model smog motors run hot.
“We can't solve problems by using the same kind of thinking we used when we created them.”
Albert Einstein |
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models916
Frequent Contributor
Posts: 1872
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Loc: Addison, IL
Reg: 05-28-10
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07-11-12 07:54 AM - Post#2246939
In response to Willys36
That 265 number is a typo, right? Everything I own runs under 200 most of the time.
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