Thermal Dynamics

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KimVanOrder
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Thermal Dynamics

Post by KimVanOrder » August 29th, 2019, 5:39 pm

How can having the timing off create more heat to make an engine run hot? If the gas in the cylinder is burning at "X" temp. And this is happening at 2000 times per minute, how dose the timing create more heat? Heat transfers to coolant, coolant travels to Radiator, transfers heat energy thru radiator to air "-Y" , and returns a bit cooler. X-Y = Temp. ????????????
KVO
Dec. '28 AA

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Rumbler
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Re: Thermal Dynamics

Post by Rumbler » August 29th, 2019, 7:53 pm

Kim, that's a great question. I'll take a shot at it, but I'm sure there's some engine guys out there that can do better.

First, the following is from Wikipedia regarding ignition timing:
===============
The need for advancing (or retarding) the timing of the spark is because fuel does not completely burn the instant the spark fires, the combustion gases take a period of time to expand and the angular or rotational speed of the engine can lengthen or shorten the time frame in which the burning and expansion should occur. In a vast majority of cases, the angle will be described as a certain angle advanced before top dead center (BTDC). Advancing the spark BTDC means that the spark is energized prior to the point where the combustion chamber reaches its minimum size, since the purpose of the power stroke in the engine is to force the combustion chamber to expand. Sparks occurring after top dead center (ATDC) are usually counter-productive (producing wasted spark, back-fire, engine knock, etc.) unless there is need for a supplemental or continuing spark prior to the exhaust stroke.

Setting the correct ignition timing is crucial in the performance of an engine. Sparks occurring too soon or too late in the engine cycle are often responsible for excessive vibrations and even engine damage. The ignition timing affects many variables including engine longevity, fuel economy, and engine power. Many variables also affect what the 'best' timing is. Modern engines that are controlled in real time by an engine control unit use a computer to control the timing throughout the engine's RPM and load range. Older engines that use mechanical spark distributors rely on inertia (by using rotating weights and springs) and manifold vacuum in order to set the ignition timing throughout the engine's RPM and load range.

Early cars required the driver to adjust timing via controls according to driving conditions.

===============
The last sentence is applicable to the Model A engine, which requires the driver to adjust timing. Timing is critical to the efficient operation of the engine and changes literally ALL the time depending on a bunch of engine factors including speed, load, fuel/air mixture and temperature. That's why a computerized engine control does it in today's cars.

So how does this affect your engine heat rejection and therefore the cooling requirements? If the fuel/air mixture combustion does not occur at the most efficient time (timing), less of the combustion energy goes into the power stroke of the piston and is instead wasted as heat, thereby causing a hotter running engine.

Hope this helps!

Cheers,
Brian

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » August 30th, 2019, 4:30 pm

Brian: " less of the combustion energy goes into the power stroke of the piston and is instead wasted as heat, thereby causing a hotter running engine."

Great try!!! So it should only get too hot when the timing is too Advanced? Or Retarded? Advanceed would be firing before top dead center causing the explosive force to have to be compressed via mechanical force before being expled into the powerr stroke. Retarded would be firinng with the piston already "down the hole" giving less power so less heat. ? .

Any way. I retimed the truck today and have been running Prestone radiator cleaner . Two times so far. And now the temp. is toping out at 198 deg. so no more losinng water to boiling out. I have rust remover in it now and will run it for the week and see what that dose..


Thanks for the info. Wee need to get the bottom line on this.. Test, test, test.
KVO
Dec. '28 AA

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Rumbler
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Re: Thermal Dynamics

Post by Rumbler » August 30th, 2019, 7:37 pm

What did you have for coolant when you last measured the temperature? Distilled water with "Water Wetter" will cool better than anti-freeze. Today's antifreeze contains glycol. When glycol is run in a slow-flowing radiator it won't cool as well as water. With slow flow rates, there is a "glycol effect" that tends to create an insulating layer of glycol on the inside surface of the radiator tubes. Modern, faster flowing systems work to minimize this.

Brian

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Neil Wilson
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Re: Thermal Dynamics

Post by Neil Wilson » August 31st, 2019, 5:27 am

Rumbler wrote:
August 30th, 2019, 7:37 pm
What did you have for coolant when you last measured the temperature? Distilled water with "Water Wetter" will cool better than anti-freeze. Today's antifreeze contains glycol. When glycol is run in a slow-flowing radiator it won't cool as well as water. With slow flow rates, there is a "glycol effect" that tends to create an insulating layer of glycol on the inside surface of the radiator tubes. Modern, faster flowing systems work to minimize this.

Brian
Brian, can you provide a definition of "slow-flowing radiator"?
Regards, Neil Wilson
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https://aafords.com/ - Ford Model AA Truck Club @ aafords.com

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Re: Thermal Dynamics

Post by Rumbler » August 31st, 2019, 3:07 pm

Thanks for the question, Neil. Andy Weideman had a cooling presentation out there that I'd like to reference but can't seem to find right now, so I'll put into my own words. The presentation refers to the Model A cooling system as a hybrid thermosyphon/water pump system, with the water pump being effective primarily for higher engine speeds. A thermosyphon system (like the Model T) would definitely be a slow coolant flow system since has no pump and the flow is only a result of the heating and cooling of the fluid through the system. The Model A hybrid system should be an improvement with the water pump, but I'm pretty sure it's still going to be a fairly slow flowing system when it comes to the glycol effect that I mentioned. Ultimately the rate of flow through the individual radiator tubes would determine if you get the glycol effect from running anti-freeze in the system. I figure that's why folks say their engines run hotter with anti-freeze. The good news is that anti-freeze also has a higher boiling point.

So my main point is that if someone is concerned about coolant temps and is running anti-freeze, one thing to try is replacing the anti-freeze with distilled water and "Water Wetter". The disadvantage is that you loose the anti-rust properties of the antifreeze, plus if your car experiences cold temps in the winter (like mine do) you must drain the system in the off-season.

Brian

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » August 31st, 2019, 3:25 pm

Update on my cooling system: After cleaning twice with Radiator cleaner the temp. dropped to 180 to 190. I than switched to Thermo cure and water and after one day, it is at 210 deg. and the coolant is turning black as it is supposed to. Also got the timing set so that should not be a factor. I'll let you all know what it is at next weekend..
KVO
Dec. '28 AA

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1crosscut
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Re: Thermal Dynamics

Post by 1crosscut » August 31st, 2019, 7:06 pm

Rumbler wrote:
August 31st, 2019, 3:07 pm
Thanks for the question, Neil. Andy Weideman had a cooling presentation out there that I'd like to reference but can't seem to find right now, so I'll put into my own words. The presentation refers to the Model A cooling system as a hybrid thermosyphon/water pump system, with the water pump being effective primarily for higher engine speeds. A thermosyphon system (like the Model T) would definitely be a slow coolant flow system since has no pump and the flow is only a result of the heating and cooling of the fluid through the system. The Model A hybrid system should be an improvement with the water pump, but I'm pretty sure it's still going to be a fairly slow flowing system when it comes to the glycol effect that I mentioned. Ultimately the rate of flow through the individual radiator tubes would determine if you get the glycol effect from running anti-freeze in the system. I figure that's why folks say their engines run hotter with anti-freeze. The good news is that anti-freeze also has a higher boiling point.

So my main point is that if someone is concerned about coolant temps and is running anti-freeze, one thing to try is replacing the anti-freeze with distilled water and "Water Wetter". The disadvantage is that you loose the anti-rust properties of the antifreeze, plus if your car experiences cold temps in the winter (like mine do) you must drain the system in the off-season.

Brian
The vast majority of Model A's that I have been involved with have used a 50/50 mix of modern antifreeze and water with excellent performance.
In my opinion the benefit of using this mixture is so great that using anything else is unwise. I have seen plenty of engines damaged from freezing and poor cooling due to the effects of rust and scale build up from using water.
If there is a glycol effect why doesn't every A suffer from it?
------------
Dave

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Rumbler
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Re: Thermal Dynamics

Post by Rumbler » September 2nd, 2019, 10:07 am

Hello Dave-
Yep, as I mentioned, there are benefits to running antifreeze and that should probably be the first recommendation. However, if someone is wanting to increase system capability (ambient temp or altitude) by squeezing a few more degrees from the operating temperature, running distilled water with Water Wetter can help get them there.

Cheers,
Brian

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » September 3rd, 2019, 4:04 pm

Still learning:

Higher compression ratios can also result in better cooling (compared to lower CR) despite higher combustion chamber pressures and temperatures at the same speeds and loads. Higher ratio heads tend to run cooler because more of the fuel energy is converted into power, and less into heat at those higher ratios.



I found this on the "ford Garage" site.. part of my problem!!
KVO
Dec. '28 AA

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » September 3rd, 2019, 4:27 pm

Found more info: ( I have a lot to look into).. :shock:

Most Model A head gasket profiles do not properly cover the two center steam holes in the Model B head and block, and are unable to effectively seal those holes.
The use of a Model A gasket profile with a Model B head and/or Model B block often results in water leaking into the cylinders, and/or exhaust gas leaking into the coolant and causing engine overheating!
Check for water in the (milky) oil, and for foaming coolant or bubbles in the radiator!


Or maybe this is not an issue. I have " Oct. 1928 block". So that would not have the 'steam' holes mentioned? .
KVO
Dec. '28 AA

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » September 9th, 2019, 4:24 pm

Just a quick update. After re-timing, flushing and flushing and rust removal and two more flushes I now am running anti freeze with now over heating problems. Thank you all for your input and tips. :D

Now onto the leaking steering gear.. :shock: :roll:
KVO
Dec. '28 AA

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1crosscut
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Re: Thermal Dynamics

Post by 1crosscut » September 9th, 2019, 6:41 pm

Glad that you won the battle on the overheating!!

Steering box leaking at the bottom end or at the end of the sector?
------------
Dave

KimVanOrder
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Re: Thermal Dynamics

Post by KimVanOrder » September 10th, 2019, 8:49 am

1crosscut wrote:
September 9th, 2019, 6:41 pm
Glad that you won the battle on the overheating!!

Steering box leaking at the bottom end or at the end of the sector?
I think end of sector. I'll be looking into rebuilding the sector with bearings and new seal..
KVO
Dec. '28 AA

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1crosscut
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Re: Thermal Dynamics

Post by 1crosscut » September 10th, 2019, 4:34 pm

Try the Penrite oil. It can do wonders for a leaking steering box.
------------
Dave

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