How Hot is Too Hot,,, SBC question.

[RC]

A bit of history first;

last summer I installed a steward high flow water pump, 180 degree high flow t-stat, and a used (vatted and checked out at the local radiator shop) walker radiator with a 16 psi cap. I have a 1600 CFM “puller”electric fan with an on at 200 off at 185 temp switch. All this at the same time I installed a vintage air system; Motor is a 327 with a powerglide.

I have drove this combo for twelve hours w/AC (normal stops) last labor day weekend from North Texas (hot) to south Louisiana (Hot and Humid ), it has been to Austin (Day at the Drags) and Fredericksburg without any know trouble (no puking out coolant on the payment when I stop).

A couple of weeks ago I installed a parts store electric temp gage(the old gage only showed C and H with the arrow hanging out somewhere in between) and wired the fan to run when need not just when the key was on, and noticed that when going down the highway at 65-70 the trunk was running around 200 and around 220 with the A/C on. Also the fan will run for a few minutes after I stop.

My question is; am I worrying for nothing, as it has not shown it’s self to be problem or should I continue to look at getting the temp down?

[Unkl Ian]

Sounds fine to me.

[Boones]

[ QUOTE ]
Motor is a 327 with a powerglide.

... noticed that when going down the highway at 65-70 the trunk was running around 200 and around 220 with the A/C on. Also the fan will run for a few minutes after I stop.


[/ QUOTE ]

I have a 327 (.060 over) with a T350 tranny in my 53 wagon with AC, it has an Al griffin radiator, 160 thermostate, electric fan (ran off a switch) in front and mechanical in its normal place. Last weekend it was 93 degrees (heat index of 104) with lots of humidity. With the AC on in trafic (and 4 bigs guys in it--- not that it should matter) the car got as high as 210 degrees at a traffic light.. without the AC it runs around 180 to 185 in the same conditions. I am going to try and add a small shroud to help out the mechanical side (but not much room) to get more air pull. On the freeway with the AC on it was around 190 degrees on the same day. Does it puke when you turn it off. The temp should go up when you turn it off, it is getting heat soaked since nothing is circulating. I know that my buddies tell me not to worry if it stays below 220

Now to your note... why is the trunk running 200? or do you mean truck?

[50mercfan]

i've read two different magazine articles where they say that a sbc can run 250 all day and not hurt it. i have no experiance with one running 250 but thats what the articles claimed.

[choprods]

variables in guages can throw ya- also a carbed engine will run cooler than say a fuel injected engine. Last but not least.....NO COOLANT LOSS/......IT'S NOT HEATING! http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Deyomatic]

You also have to consider vacuum advance characteristics, are you running headers and using the temperature sender location in the head, are you using the temp gauge sender location in the intake...etc.

[MercMan1951]

Is it a good quality gauge or a $20 one? I've noticed with cheap gauges that they tend to run on the high side, rather than better quality gauges like Autometers...you may not really be running that hot...

[36-3window]

the USED walker radiator makes me wonder why it was taken out of a car...also,is it the base Cobra or the heavy duty Z-series?


a friend's 32 with a ZZ4 motor , walker Z raditor , spal 2700 CFM puller fan and air conditioning never gets over 180 degrees , even idling in traffic. i think the heavy duty radiator and the high performance fan is the answer

[Boones]

Deyomatic,,, you brought up a question I was wondering. In my case I am running headers and I do have the temp gage in the head. The temp gage is a SW brand.

Does the temp gage in the head read hotter then it would in the intake manifold? and is it more accurate one way or the other?

[Deuce Roadster]

http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

Boones.......

I have had two senders in the engine connected to a rotary switch. That way.....with the flip of a switch..I could check either location.........and the head was about 10 to 15 degrees warmer when the engine was fully warmed up.

Why Not move up to a 180 or 195 thermostat ? You are that warm most of the time anyway. The 160 is open all the time (past 160). The idea is that with a 180 or 195 the coolant will stay in the engine longer and that allows the coolant to be in the radiator longer.........to cool off. I use a 195 in the Deuce and the 40 Coupe. It is dyno proven that carbed engines make more power at 190 - 200 than at 160. They get better mileage too.

Just my 2 cents.

http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Fat Hack]

Boones, I've run my temperature sending unit in the cylinder head and in the intake manifold on the same car (a 69 Chevelle with a 350) and noticed very little difference, not enough to show up convincingly on my cheapie gauge, anyway!

180-230 is an acceptable range for typical SBC operating temp, and in a car pushing AC in hot weather, 200-220 degrees isn't something to worry about. I found my Chevys ran best at 190-205, and six cylinders like 200-220...I think you're okay!

[MercMan1951]

Like Deyomatic, I was going to ask the question about the temp sender being in the head or the intake manifold, but I was unsure if that question applied to small blocks as well as big blocks...since I am limited in my SBC resources...I had heard (as in the case of my big block) that a "true" temperature for it would best be achieved in the manifold, where you're measuring heat of the coolant rather than residual heat off manifolds, combustion chambers, etc. Oddly enough, my BB only had a port for the sending unit in the stock cast manifold...none were in the heads, (they were pass. car heads circa 1967), but I have seen other BB's that had them in the heads. Mine were not machined in the same place as the other BB's I had run across.

So I guess that what I'm saying is that it would be a more accurate reading of "overall" engine temp if it's in the Manifold, no?

FWIW, my warmed over 396 Chevelle would run 185 driving, but if I sat in traffic, it would climb past 240 sometimes, especially on hot days...even with a 4 core radiator (new), a 180 thermo, a fan shroud, and flex fan. I used AutoMeter gauges...it puked coolant everytime I shut it off (no catch can.)

Have you checked your timing lately?

[Crestliner]

Before the cobra came out the best one was the coolmate. I had one in a new 28 sedan delivery. Twenty minutes from start up it was boiling when setting. Driving with the air it ran 200 or higher on the road. Pull off the highway and it pegged out. Fought with Walker for 3 years and finally got Harry and he said can't be the radiator and he would prove it by sending me another. Put it in without the fan, set outside facing the wind (not strong) and let it idle for 45 minutes and it ran 185 and no higher. To make this long story short,Walker put out some bad radiators and didn't want to admit they did. I will buy mine elsewhere.

[RC]

The gage is a $20 unit,
the used walker was from a friend of mine who put a griffin in,
it has never puked coolant.
The sensor is in the intake next to the t-stat.

This has bugged me for over a week, I think I am going to go with the wisdom

"IF it ant brok don't fix it"

oh, yea it's a truck http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[MercMan1951]

Here Here, RC, there's a reason why stock gauges only read
H----C, alot less headaches!

[choprods]

My real cure is this....NEW ENGINE /NO GUAGES!
theres too much stress in knowing what the hell the inside of my motor is doin!
Besides if a Cell phone is distracting to drivers wouldnt lokin at the temp guage every ten minutes be worse...... http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Boones]

Randy, you are probably correct about the thermostat.. It was what I had when I put it together. When i put it together the motor was in Seattle and I did not think about the hotter temps down here.

[flynj1]

You should be ok. as for how hot is to hot maybe this http://www.jalopyjournal.com/ubbthreads/images/graemlins/blush.gif

[C9]

[ QUOTE ]
i've read two different magazine articles where they say that a sbc can run 250 all day and not hurt it. i have no experiance with one running 250 but thats what the articles claimed.


[/ QUOTE ]

I agree with that - except once you get to that point most times you're dealing with thermal runaway and headed for other problems.

Keep in mind too that the recommendation for temps in an automatic trans is to try to keep it below 200 degrees F.
Around 180 is good for the trans, drives out the moisture etc.
There's a chart for automatics kicking around somewhere and it shows a 100% life expectancy for transmissions run under 200.
210 drops the life expectancy to 95%, 220 to 85% and so on with the life expectancy dropping steeply to nearly zero once the trans hits 260 or so.
All of which indicates to me that running an engine coolant temp of 250 would be getting the engine oil to the point where it couldn't do it's job.

[ QUOTE ]
You also have to consider vacuum advance characteristics, are you running headers and using the temperature sender location in the head, are you using the temp gauge sender location in the intake...etc.

[/ QUOTE ]

You definitely need the vacuum advance sourced to manifold vacuum. If not, you'll be overheating in traffic and at idle.

Having the sender in the intake just above the heads where the coolant is the hottest is probably the best place to run the temp sender.
That'll give you an overall view of how the whole engine is doing.

All that said, I'd bet your problem is simply a not-too-accurate temp gauge.
Bite the bullet, buy a quality temp gauge, preferably a mechanical and you'll get accurate readings.

There's a reason cheap gauges are cheap....

[dixiedog]

[ QUOTE ]
You definitely need the vacuum advance sourced to manifold vacuum. If not, you'll be overheating in traffic and at idle.


[/ QUOTE ]

The dizzy in my 406 SBC is a Mallory with out a vacumn advance, does this effect it also? I have a overheating problem puking with a 16lb cap and no thermostat, could the distributor be a part of the problem? My Autometer guage reads 230 with the sender in the manifold.

[C9]

[ QUOTE ]
The dizzy in my 406 SBC is a Mallory with out a vacumn advance, does this effect it also? I have a overheating problem puking with a 16lb cap and no thermostat, could the distributor be a part of the problem? My Autometer guage reads 230 with the sender in the manifold.

[/ QUOTE ]

Yes, it does affect it.

Do a search for an article I wrote titled "Got Time?"
It turned into a good discussion about timing systems, how they overlap and all that.
It may help.

My own experience with sourcing the vacuum advance was that my 462" roadster overheated at idle and in traffic when the vac advance was sourced to ported vacuum in error.
Changing to manifold vacuum cured the overheating problem and the car will run a max of 198 degrees in summer traffic.
(100 degrees plus here in the Valley.)
Highest temp I've seen on it was 205 idling through the (long) line at In & Out Burger on a hot day.

[48_HEMI]

I may have missed it. but the main issue with heat is the temperture the coolant boils
Water is 212 at sea level
antifreeze increases the boiling point
a pressure cap increases the boiling point. 3 degrees per lb. 15lb cap= 45 degrees
so with antifreeze and a 17lb cap your coolant should not boil till at least 270-275 degrees so 230-240 would not be a worry, A recovery system with a large enough container finishes the system. the pressure increases the minute you shut down the motor. as C-9 mentioned transmissions need a good cooler to last

[RC]

[ QUOTE ]
Bite the bullet, buy a quality temp gauge, preferably a mechanical and you'll get accurate readings.

There's a reason cheap gauges are cheap....

[/ QUOTE ]

Some time in the life of this 36 ford truck someone put a 56 chev PU instrument cluster in the dash, you know the V shaped thing. I am going to replace the whole thing, repair the dash and put in a set of gages, like VDO, Classic, or SW.

One thing that makes me think the cheap gage is close is that I have a Painless fan control that is mounted in the intake next to the t-stat (temp sensor on the left, fan sensor on the right). It is the on at 200 off at 185 version and it seems the electric fan starts at about the same time as the gage shows 200, it’s not exact but close.

I was thinking about moving the trans lines from the rad to a external cooler along the frame. I don’t know how much heat an old powerglide generates or after reading C9’s post how much it can take.

The rad is an old walker maybe made in 87 or so, it was on my friends 34 coupe with TPI SBC for many years, it would leak at a crack on the top tank and he would fix it himself, after several “fixes” he purchased a griffin and placed the walker on the shelf. I found out he had it and picked it up, took it the a biker chick who runs her own radiator shop and she repaired the crack for me, she said it was kind of old, but if I wasn’t going off road it should work just fine.

Timing and vacuum is another thing, I set the timing at the very top of the small original “pointer” on the block. The truck starts very easy cold or hot, so I though it was OK, again I will try to find C9’s post about timing and give it a read.

I can’t remember exactly where the vacuum advance line is connected.
I’ll have to check that. http://www.jalopyjournal.com/ubbthreads/images/graemlins/confused.gif

[motor mikey]

Hey dixie, do you have the steam holes drilled in your heads wtih that 400? Actually, mid 90's Camaro's electric fans didn't kick on until 230. I wouldn't worry about it unless it pukes.

[Satinblack]

Lots of good input on this one!

I will say that I am running a big block 402 in the desert. I have a manual fan with no shroud and an push electric fan that cycles with its own sensor in the head. I am running my temp sender in the other head. I also have a new radiator. My truck runs at 185-195. The thermo stat is 180. I never use 160, although you dont want your engine to run hot you dont want it to run cold either.

The only other comment I would like to make is the use of high volume water pumps and oil pumps for that matter on a street car. to much flow is as big a problem as no flow. If water passes thru the radiator to fast it wont have a chance to remove the heat. Refrigeration 101. Satin http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

[Scotch]

Did you say your fan doesnt come on until you've reached 200? If there's a way to make it come on at 195 or 190 I'd do that. There are programmable thermostatic switches for this purpose, and if you'd like your car to run a little cooler, this is an easy way to get it done. The electric fan kits Flex-a-lite sells have this programmable thermo switch feature. I like it cuz you can set it up the way you like. Since I live in SoCal I'm more concerned with keeping it cool on hot days idling for ling times in freeway traffic - certainly my "worst case" scenario and it happens all too often. With the programmable switch, I can control the temp by dialing in the fan "on" temp. By playing with timing, advance, carb richness, water/coolant ratio, water pump pulley dia., T-stat rating, and these programmable fans, I've been able to fine-tune the coolant system(s) in my car(s).

Anything over 210 for any length of time will shorten the life of the oil. Personal opinion- not researched fact. But, if my car spends a bunch of time at 210-plus, I'll plan to change the oil early. I try to keep it at 190 all the time.

Scotch~!

[dixiedog]

C9 I found the "Got Time" post - all I can is WOW!! That took some serious time and sooo much knowledge, I copied, pasted to a Word file and printed out all the pages for tonights reading, thanks very much.

Motor Mikey, I don't have the steam holes drilled, I do believe I need to keep "burping" out the air pockets, I have heard that it can take up to 5 burping sessions to get all the air out.

[Slide]

RC- I noticed you mentioned you are heating at hiway speeds. When I was working for my dad, I built a 37 Ford for a dude that put a ZZ430 in it. He ran cool enough in traffic, but heated on the hiway. He had a single electric fan, and no mechanical fan. The elect. fan was controlled by an adjustable t-stat to come on @ 180. We found that the elect. fan was actually IMPEDING air flow at hiway speeds. We put a kill switch on the fan, so he could cut the power to the fan altogether on the hiway. Fixed his problem. The air naturally going over the radiator at 70mph was more than the fan was sending thru the radiator! (Keeping in mind that the motor is working significantly harder at speed than idling.)

[RC]

[ QUOTE ]
He had a single electric fan, and no mechanical fan.

[/ QUOTE ]

This is the same as my setup.

[ QUOTE ]
We found that the elect. fan was actually IMPEDING air flow at hiway speeds. We put a kill switch on the fan, so he could cut the power to the fan altogether on the hiway. Fixed his problem.

[/ QUOTE ]



I think I am going to unhook the fan sensor and take the truck for a drive; I live in the country so I can hit the main highway and run 70 right away. I want to see what if any different the temp is when going highway speeds no traffic and no fan.

[Tudor]

Dixiedog - your mallory distributor has a mechanical advance curve instead of one actuated by the vacuum. If your initial timing is set correctly it will have no effect on the temperature - the vacuum has nothing to do with it

[Boones]

I have put my electric on a toggle switch. I only run it when the temp gets above 190. Never have to use it on the highways. Just in stop and go traffic or going thru the local burger drive thru on hot days... (thou with the AC on and temps near 95 or 100 I may have to on the freeway also??? will find out soon when I drive up to Des Moines in a few weeks.

[Hot Rod To Hell]

[ QUOTE ]
Just in stop and go traffic or going thru the local burger drive thru on hot days...

[/ QUOTE ]

Oh, what I wouldn't give to be able to take my car through a drive thru.... They always say something about not being able to hear or something...(I can never really hear them to tell what they're saying...) http://www.jalopyjournal.com/ubbthreads/images/graemlins/grin.gif

My car runs 180 if I'm moving, 165 w/ the fans on.
If I get stuck in traffic I'll usually turn my fans on around 200-210, and then it'll stay 185 all the time. My oil runs about 175 (in traffic... 140 moving) and my tranny runs at 170-180.

[Bryan]

C9's excellent threadis here http://www.jalopyjournal.com/ubbthreads/showflat.php?Cat=&Board=UBB1&Number=388060&fpart=& PHPSESSID=