running hot questions

I am running a 350 SBC with 350TH trans. and it has been running 200 degrees in this hot texas weather(95 degrees outside). now that is when I am doing 75mph on the highway. City driving is like 180-190. I was wanting to put in an ac but that would kick up my temp another 10 degrees at least.

200 seems hot to me any advice would be great.

thanks in advance!

 

I dont think 200 is really hot for 95 degree weather athough mine runs cooler than that most of the time. You could probably get away with it, some changes to your set up (shroud. fan type /spacing etc..) might help it cool better

 

What kind of car is the engine in? Could be you are not getting hot air out fast enough. What temp is your thermostat?

 

Stock engine?? Vacuum advance?? Intake/exhaust mods??
What I can offer right now is to make sure the ignition is running manifold vacuum. SBCs like manifold vacuum to keep temps down. Too, make sure your gauge is accurate. Electric guages use resistance for indication, more or less resistance will lead to inaccurate readings.
And, 200º is not that bad. 240º with a 19# cap is on the upper limits, but you're not there.
Remember that the gasoline engine is a HEAT engine; needs heat to work properly. Since almost all engines run a 195º thermostat from the factory, I'd say you are worrying about nothing right now.
Cosmo

 

200° on a 95° day ??? I WISH mine ran that cool !

 

200 really isn't hot at all as has been mentioned..
I had a similar problem with my old 33 Ford truck. Around town it ran cool, 170-180 most of the time..Hit the highway and off it went. It would climb to 205-210 on average, and higher if i went faster.
After failing to find the problem, i contacted my local radiator shop with it.
Long story short, my radiator was not efficient enough to cool it at higher speeds.
I had two problems, one was it was actually pushing the coolant through the radiator faster than it could cool it ( this was a small core radiator), AND the style of core i had was acting more like a wall funneling the air around it rather than through it..More so the core style.
I had a new core built with larger tube's, and a core design , much like that of semi's..flat design which allowed the air to flow through it much easier..
Solved the problem completely. Always ran around 170-175 after that.

Might not be your problem..but just something else to think about if all else fails.

Tony

 

Sounds like what my 52 does! 170-180 around town on 70-80 degree days, 90 to 100 degree weather..up it goes 200-210-215!! Explain the "sbc's like manifold vacumn to keep temp down.."

 

I've had good luck with running 50/50 water and coolant for a few days, this coats the system, then drain it all out. Run water (no coolant) with a good cooling product: Purple Ice, Engine Ice, Water Wetter, etc. Of course, an aluminum radiator will help too. We usually run 160 or 180 thermostats. And as mentioned before, make sure you're getting a good amount of air.

 

I Lived my first 35 years in my dads radiator shop. If you car runs hotter at highway speed, you could not be diverting enough air through it. This was a real problem with late 80s early 90s firebirds. More than once a car was bought to our shop with a multitude of replaced parts waterpump, radiator thermostat etc. and all that was wrong was the air deflector under the bumper was missing and the car didn't have enough grill area to cool the car so it had to have the deflector.You should be running a thermostat if you are not as mention above the coolant could be moving through so fast the radiator can't cool it. A more efficient core could possibly fix the problem even if you still had the problems I mention here. Radiators are innefficient for a couple of reasons. The fins are stopped up (usually the problem with farm trucks) and air cant flow around the tubes or the tubes are stopped up internally and the coolant can't flow through. Older cars didn't run over 200 degrees as the norm. Pontiac v8s did because of that grille area thing I mentioned earlier. Chevys ran cooler. I guess the short version would be I agree completely with what TONY said earlier.

 

Fan shroud. 7 blade factory-type steel fan with a viscous clutch (it's supposed to engage when underhood temps reach a certain level).
I like to run a 160-degree thermostat in the summer (hot Atlanta). That way the thermostat opens sooner and gets the water circulating, and the cooling system doesn't have to play catch-up. If it opens at 190 degrees, you're that much closer to overheating when you're on stop and go traffic.

Your results may vary.

-Brad

 

If you use ported vacuum (from the carby), the vacuum goes away at speed, the timing retards, and the heat goes up. Manifold vacuum just increases with rpm, but lowers at full throttle, which is what you want.
Usually not a problem, unless a body decides to do it different than the factory, or follows a buddy's advise, said buddy who has all of his relatives running in fear whenever he has a screwdriver in his paw.

Cosmo

P.S. a trick used on early Jags (which had a well-deserved rep for overheating) was to use a close-fitting shroud around the fan. Need not be sophisticated, either, just a drum around the fan works wonders.

 

You don't even need a fan at highway speed. The car should get cooler at highway speed. I do think the 160degree thermostat is a good idea. And every situation is different. I think everyone has given good advise but the fix will be making the radiator itself more efeccient.

 

Exactly..I ran an electric fan on the 33 i mentioned above, and a 32 i built with a blown sbc running a Walker rad..no mechanical fan's or shrouds. They both were running 160 stats though..
On the highway (once i had the truck's rad rebuilt) i would shut the fan off on both and it NEVER got hot. They only needed the fan at low speeds.
I forgot to mention above, the truck was running an sbc as well.

 

In my experience, the only time ported vacuum goes away is at idle.
Which is why you should source the vacuum advance to manifold vacuum.

Ported vacuum came into being during the early smog years so the engine would run hotter and cleaner.
Never mind that you can't hardly get through summer traffic with the vac advance hooked to ported vacuum.

Here's an excerpt from a timing article I wrote.
(It's in the archives and titled, "Got Time.")

~~~~~~~~~~~~~~~~~~~~~~~~~~

What we’re dealing with here is in effect a variable venturi.
At least it is as far as ported vacuum goes. The variable venturi bit due to throttle blade position.


I got curious about a comment I heard about manifold and ported vacuum going to zero at WOT (Wide Open Throttle) and ran a little experiment.

The car - 32 roadster - weighs 2400#, engine is an overbored 455 with 462 cid, 9/1 compression ratio, Edelbrock Performer intake, Carter 750 cfm competition carb with electric choke added later and a Crower Compu-Pro #1 cam which has about 262 & 266 degrees advertised duration intake and exhaust with 112 degree lobe centers. It’s a smooth cam and the car when warm idles @ 19" vacuum.

The dash carries a large (2 5/8") S-W vacuum gauge which compares favorably with the vacuum/pressure test gauge I have.

Advance is 8 degrees initial and all in at about 2600 rpm with a total of 32 degrees. Vacuum advance is about 16 degrees and sourced from Manifold Vacuum (MV).
The car runs very well on 87 octane in summer and winter and does not overheat in traffic.


Firing the car from dead cold and on the elec choke, MV reads 18-19" and idle is around 900-1000 rpm.
Ported Vacuum (PV) read 12" on startup.

Once the engine warmed up, MV reads 19" and PV reads zero at an idle speed of 500-600 rpm.

Cruise at 40 mph with a light throttle setting on a flat road gives you 18.5 - 19" MV and just about the same on PV.

Rolling the throttle in about half way shows 8 - 10" of vacuum on both MV and PV during light acceleration.

Once at 60 mph MV read 18 - 18.5" vacuum (keep in mind this is a very light car) and PV read
10".

Flooring the throttle at 40 mph or 60 mph brought the MV down to 1" or so and PV to zero.

At idle with a fully warm engine, MV reads 18.5 - 19" and PV reads zero.

The lack of additional timing at idle is what creates an overheating problem in GM engines and many others.
It takes time to burn the lean idle mixture and additional advance is required to get the process underway early and avoid overheating.

Exactly the same thing (overheating) would happen with the timing severely retarded in an engine under load at a higher rpm level.

There’s a lot of confusion out there about timing, both centrifugal (mechanical) and vacuum as well as the vacuum sources to use.
The key thing is to realize they are two different systems that work together to give optimum spark advance for a particular condition and key on rpm as well as load.

To my way of thinking perhaps there would be less confusion if the vacuum advance cannister was called the vacuum retard cannister.
I’m amazed at the lengths some go to, to cure an overheating problem that can be solved in most cases simply by selecting the correct vacuum source.

Granted, most of my experience has been in cars with small engine bays and many times not the biggest radiator in the world, but I note, the bigger cars have the same amount of timing and overheating problems as the small car guys do and for some reason many car owners avoid doing something as simple as swapping vacuum sources to cure overheating and prefer to throw money at the problem.

As far as spinning up a little experiment, I’m not trying to prove anyone wrong here, just got curious, had some free time and those are the results I came up with.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An additional note; for those of you who live at a higher altitude than where these tests took place, you’ll find that your vacuum levels at no-load (idle) rpms will read lower.
To the tune of a 1" vacuum loss for every 1000' of altitude.
The tests took place at 350' altitude and manifold vacuum at idle read 18.5".

After moving to Sunny Arizona and ending up at 3300' altitude the manifold vacuum now reads 15.5".
Highway figures and under load vacuum levels remain the same as they did at the 350' level.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Written from research on timing figures and real world experience.

 

Wow! that is all some good advise. I think my radiator may be the problem. It is really clean to the eye. My timing vaccum is to the manifold. I am running dual elect. fans(I dont think that is a problem at highway speeds either)MY car just has a mild cam headers and alum. intake, nothing crazy. I will check into a new radiator. Also I am running a trans cooler in front of the radiator( I would thnik that wouyld help cooling not hurt it)

Sanpedro

 

Are you sure the vacuum advance is working?

Positive the cam is in time?
(Reason I ask, my pal just got a 46 Ford with 302 SBF and the fools who put the engine together had the cam a tooth off.)

What kind of manifold vacuum levels do you have at idle?


Some of the guys have made some good points about underhood air flow.

You still haven't mentioned what kind of car it is.
Knowing could help us help you with your problem.