so did my new distributor and correct timing. it no longer even thinks about heating up on me.

 

Glad to hear it.

 

I don't wish to start a flame war, and I'm not picking on Hiball, but I see too much mis-information in this thread. This is NOT how a thermostat works. The thermostat is designed to keep the temperature above a design point. Once the temperature rises above the design point, the thermostat will remain open. In other words, the job of the thermostat is to allow the system to heat up, not help cool it down. Furthermore, a higher flow rate will improve cooling; removing the thermostat will undoubtedly allow for higher flow. In support of this statement, browse a Summit or Jegs catalog. You will find listings for high flow thermostats and high flow water pumps that are all advertised to improve cooling. By analogy, your radiator works better as your speed increases because the air flow across the radiator is higher; a larger (or faster turning) fan also improves the air flow rate resulting in better cooling. I can provide all the thermodynamic theory if anybody is interested.

In the case of race cars, it may actually be necessary to restrict the water flow to avoid cavitation in the water pump due to the high impeller rotation velocity.

Sorry for the long post.

 

So.........

Is the glass half full or half empty? Or should I say engine.

 

fasttexan, I think we were saying pretty much the same thing but worded differently, I was trying to keep it simple...but I don't totaly agree with your statements about more flow will increase cooling..the bottom line is the original poster solved his problem, posted on page 2, by installing a thermostat and his truck is back running without heating problems

 

The only reason a thermo stays open is if the rest of the system cannot compensate for the heat gained in the motor... ie rad too small for the job. It stays open becasue it wants cool water to close it, but cool water is not showing up, when it sticks open long enough, guess what happens, you overheat and have to pull over.
Hi flow thermos and water pumps are to get cool water in fast, and hot water out fast, not to circulate it at a high rate.
Race cars are a bad anoalogy, they do not sit in traffic, and when drafting have to break out to get flow across the rad to cool back down.
1/4 mile cars are even worse, as, they return to pit lane hot, and use an electric pump and fan to circulate water in the pit while waiting for the next round.

You bust out all the theory you need to to make yourself a believer, until you've tried running with an open system, vs a thermostat controled system, you have just that... theory.

My 390 would run darn cool out on the highway with no thermo, so cool the heater would not blow hot, and then heat up to beat heck in town... and overheat in traffic... This with a 7 blade fan, brand new 4 core rad, and proper fitting shroud.
I put in a 180* thermo, and the needle never moves once warm... not even now in summer conditions, sitting in grid lock, cruising 75mph, or toolin' along in 117*F city traffic.
To take it a step further, the truck had overheating problems last summer, with the 160*... water was being circulated too quickly... the 180* keeps it in the rad longer, exchanging more heat... creating a larger delta across the system, allowing for controled operation.

On top off all that, suppose you set it up to run geat with no thermo... now take a drive up into the mountians where it's 40* cooler, and presto, the vehicle is going to run cool, now sit in traffic, and presto, car gets hot. Running with an open system, or restricted system relies on airflow and extermal temps to be constant in order for the system to control temps. As soom as one variable changes, the operating temp of the system does as well.

 

cleanLX I dont think you could have explained it any better it better.

 

I can verify that with my car. the temp here in NC is topping 100 degres close to every day. when i am driving down the road my car did fine. When i get in to town and stop light to stop light it really starts to heat up.

I checked the thermostat and it was stuck open. I got that changed and amazingly it it runs just as cool as it did when it was brand new.

 

well done CLEANLX

 

Not totally true. Yes, the thermostat helps the cooling system warm up sooner. But by closing and stopping circulation thru the radiator it gives the coolant in the radiator longer to cool down. There by allowing coolant entering the block when the thermostat opens to take longer to heat back up and allowing the hot coolant now in the radiator to have longer to cool down. Unless you have a minimum of a cooling system the thermostat should not open and stay open after warm up. It should cycle open and closed for best cooling. As to the high flow thermostats, they are designed to allow a quick exchange of cooler coolant for hot in the block because race motors build heat very fast. Has nothing to do with the thermostat staying open all the time. To prevent cavitation in the pump the rule is just slow the pump speed down with different pulley sizes.

 

Also not totally true. If the water in the radiator is retained in the radiator, it will cool down more. However, the rate of heat exchange in the radiator is dependent on the temperature differential between the two mediums (coolant and air). Thus, as the coolant cools down, the rate of heat exchange with the air becomes less. Meanwhile, the coolant that is not in the radiator is not being cooled at all but, in fact, is being heated. Because we're interested in maximizing heat removal in the radiator we want to keep the temperature differential between the coolant in the radiator and the air as high as possible. This is achieved by exposing the highest amount of fluid (read increasing the flow rate) to the radiator, not by stopping the flow. If we remove the thermostat, we lose our temperature control, but actually increase the cooling rate of the radiator.

I didn't say that the high flow thermostats had anything to do with the thermostat saying open. I said that they are advertised to improve cooling (because of the higher flow rate through them).

I'm a control engineer by profession and I program temperature control loops around heat exchangers everyday. If you won't take my word for it, do a search on heat exchanger design on the net.

 

Besides working on automotive cooling systems I've have worked on boats with water to water exchange systems (the only way to fly if you have a constant supply of cold water). If all you are gonna do is drive fast you don't even need a fan because your speed gives you sufficiant volume of air for cooling. But if you remove the thermostat from an automotive system, it will in almost all cases do a slow overheat as the coolant does not stay in the radiator to cool enough to not come out of the engine warmer the second time around than the first, and so forth. I've seen it way to many times to not know it is true. I agree with you second accessment of the high flow thermostats as they help cooling, but only if the coolant gets enough time in the radiator to cool enough to be able to cool the engine enough. The coolant can't pull enough heat out of the engine if it doesn't stay in the engine long enough to cool the engine down or if it is too hot to tart with. My dad was an engineer and I work with engineers in the aircraft industry as a tech. Just because theory says so doesn't mean real life works that way. Just way to many variables. Back in the '60s we pulled the thermostats to improve cooling. Of course it didn't work and caused major overheat problems. Tried restictors but finding the right size was taking to much testing (wear on the race motor with a limited money). Suggestion by dyno shop owner and very successful racer was to remove the valve from the thermostat and try that. Worked on three different brand of engines. Then we knew what size restrictor to run (never did change out the modded
thermostat (if it works don't screw with it).

 

That complete piece of crap has a truck engine-lower compression to start with. Let me guess, that complete piece of crap has a high mileage engine-less friction. Best thing for a piece of crap like that is fresh oil and a long drive-keeps the internals clean, including the combustion chambers.

My piece of crap was so loose that during winter (snow, ice, some sub-zero) it started when others wouldn't. The one thing it had trouble with was keeping the windshield defrosted, and that's with a thermostat.