Should you run a car without a thermostat?

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dart gt

dart gt

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I have a 1969 318 with a 455 purple shaft cam,edelbrock intake,600 holley carb and hedders.The problem im having is the car will start pinging when it gets around 180 degrees.I tried setting the timing at different degrees and nothing helps.Tried running boost and that dont help either.Read an article in the new hemmings book and they say you get better flow and reduces pinging.Has anyone run there cars without one.Thanks
 
What are you running for total mechanical timing, and are you running/ not running vacuum advance?

180 IS NOT warm, and if it won't run at 180, don't expect to fix it by trying to run it colder --ain't gonna happen. Don't run the car without a stat
 
Absolutely not. You need to fix the actual problem. With no thermostat, the coolant flows with restraint and doesn't stay in the radiator long enough to cool properly. It can actually run hotter w/o a t-stat under certain condition.
 
Mopar to ya said:
Absolutely not. You need to fix the actual problem. With no thermostat, the coolant flows with restraint and doesn't stay in the radiator long enough to cool properly. It can actually run hotter w/o a t-stat under certain condition.
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x2
 
Just take out the thermostat and test it. See if it pings if the engine is running cooler. Some people say cars will run hotter with out the thermostat. I have never experienced that. Mine always run cooler and never warm up.

What do you mean boost? Is your car forced induction? If the engine temp is 180 then your engine is cooling properly but you could bump down to 160 high flow t-stat if your temp test proves that lower engine temp helps with the pinging. Running lower than 180 will shorten engine life slightly like in a 200 k engine, it may drop your lifetime by 30 % and cause the oil to have to be changed more often so there are drawbacks to running a colder motor. Sometimes low end throttle response and driving in cold weather can be problematic with a colder engine also.

What fuel are you running? How about elaborating completely on your engine build, gear ratio of rear end, transmission gear ratios. Exhaust details from head to tailpipe, carb jetting. Purpose of car. Someone here probably knows alot about pinging.

I had a fresh built 455 ci 10.25 compression with cast iron heads. I had to run a 160 thermostat, colder plugs, and 93 octane gas to keep it from pinging constantly. My rear end gears were 2.21 which added to the ping factor. I ran a 650 carter carb and do not know the jets.
 
I have 355 sure grip for gears,2.5 in exhaust,am running at 12 degrees and 34 initial,with a A833 4 speed.I meant octane boost in 91 gas.
 
dart gt said:
I have 355 sure grip for gears,2.5 in exhaust,am running at 12 degrees and 34 initial,with a A833 4 speed.I meant octane boost in 91 gas.
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When does it ping?? Like cruise or wide open or on a hill at part throttle or all the time?

What heads are you running? 69? Do they have new valve seats? Hell could have burnt valve seats, carbon built up in the combustion chamber too.


Can you record a video and post it here?
 
I bet dollars to doughnuts you're runnin hotter than 180. What kinda temp gauge you got? The cheapest one you could find? The hotter an engine runs, the more prone it is to spark knock.
 
I run mine with no stat - but do run a restrictor plate to control the flow. I have an electric wate pump with no recirc so using a T stat is not really an option. Trial and error on the restictor orifice an Mine seems to stay in the 180 range for the most time maybe bumping to 190 or so in prolonged warm weather driving.
 
The reason you should ALWAYS run a thermostat is to ensure the rear of your engine block gets exposed to cooling water.

With the thermostat and temperature gauge located at the front of the block, removing the t-stat causes the cooling fluid to be pulled back into the radiator (recirculated), which results in water only circulating through the "front" of the engine. The t-stat "cycles" to ensure cool liquid is forced to circulate over the entire engine (front to back).

If you run without a t-stat, it's very possible your temp gauge is giving you false readings, since the only portion of the block that gets cooled water is the front - where both the temp gauge and t-stat is located...which means your back cylinders are probably running considerably hotter than your gauge indicates.

On the detonation, check to make sure you don't have any vacuum leaks; check the vacuum advance to ensure it's working properly; make sure you're not sucking any air through the carb from an open port or internal crack; check to ensure your operating temperature is consistent with the t-stat you're running (remember, you can run too cold a thermostat, which is nearly as bad as running with no t-stat); make sure you don't have "bad" fuel (or fuel with lower octane than your engine requires); and if all of these measures check good, check your static timing to ensure you haven't jumped a tooth on the timing chain; and, finally, check cylinder pressure to ensure it's consistent with your build and fuel octane.

Again, IMHO, just a few things to be aware of, and to try.

Southernman
 
Southernman said:
The reason you should ALWAYS run a thermostat is to ensure the rear of your engine block gets exposed to cooling water.

With the thermostat and temperature gauge located at the front of the block, removing the t-stat causes the cooling fluid to be pulled back into the radiator (recirculated), which results in water only circulating through the "front" of the engine. The t-stat "cycles" to ensure cool liquid is forced to circulate over the entire engine (front to back).
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I'd like you to explain why this is so, IF it is so. Where did you get this information?
 
30+ years in engineering and common sense...

Think about the location (better yet, look for yourself) of the thermostat and adjacent "ports".

When it's closed, the water is FORCED to the rear of the block and cylinder heads via pump pressure. As that pressurized water absorbs heat from the combusion process, that heated water opens the t-stat allowing it to return to the radiator for cooling. As the heated water is displaced, the in-coming cool charge closes the t-stat again, so the process can be repeated.

When the cooling system is optimized, temperature will be maintained at/near the t-stats rated value and, though the t-stat is cycling, in an optimal system, the temperature should remain fairly consistent.

The reason "race" engines get away with running only restrictors, is because they run at very high rpm, which has the effect of forced cooling - similar in function to an engine with a thermostat - which relies on thermal cycling instead of rpm to accomplish the same thing. For street applications, the thermal cycling is required when the pump is operating at the "lower" end of the pressure scale, and idle/cruising rpms.

I'm not stating anything "new" here, just how the systems were designed to work.

Southernman
 
Dart GT, one other question:

Does the car ping if you disconnect the vacuum advance and plug the port at the carb ?

Southernman
 
Southernman said:
30+ years in engineering and common sense...
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Sorry, nope. Doesn't do it for me. NO WHERE have I ever read that a thermostat somehow magically causes water flow to divert to the rear of an engine and back.


What I'm asking for here is a quote from a recognized text, or other authoritative source.

Sometime ago I found myself here:

http://www.stewartcomponents.com/Tech_Tips.htm

They don't seem to agree with you
=============================================
These guys seem to think:

http://www.arrowheadradiator.com/14...apability_in_high-performance_automobiles.htm

[FONT=arial,arial,helvetica]The heat load to the cooling system is related to the flow through the radiator and the temperature drop through the radiator by the following expression:[/FONT]
[FONT=arial,arial,helvetica]Q = M * cp *dT[/FONT]
[FONT=arial,arial,helvetica]Where Q is the heat load BTU/min., M is the mass flow rate of the coolant in BTU per pound per degree F, dT is the temperature drop through the radiator in degrees F[/FONT]

[FONT=arial,arial,helvetica]Looking at the previous expression, we can see that slowing the coolant down is the wrong way to go[/FONT]

[FONT=arial,arial,helvetica]What would happen if we increase the coolant flow?[/FONT].....................


........................[FONT=arial,arial,helvetica]will result in better heat transfer performance. There are some cautions to be observed in increasing coolant flow rate, however. Going too far may result in aeration and foaming of the coolant, possible damage to the radiator by overpressure, cavitation of the pump, due to excessive pressure drop through the radiator, and erosion of the radiator tubes.[/FONT]
=============================================

Nowhere in these discussions does anyone say anything about a restriction being necessary to promote circulation in the engine block and heads.
 
I vote for using a thermostat and backing off timing .
TXDart
 
Let's see, are you referring to Arrowheads text on T-stats that state:

THERMOSTAT
Severe overheating can often damage a good thermostat. Therefore, if the engine has overheated because of another problem, the thermostat should be tested or replaced before the engine is returned to service.One way to check the thermostat is to start the engine and feel the upper radiator hose. The hose should not feel uncomfortably hot until the engine has warmed-up and the thermostat opens. If the hose does not get hot, it means the thermostat is not opening.

Another way to test the thermostat is to remove it and dip it into a pan of boiling water (it should open). The exact opening temperature can be checked by using a thermometer.

If the thermostat needs to be replaced, install one with the same temperature rating as the original. Most cars and light trucks since 1971 require thermostats with 192 or 195-degree ratings. Using a cooler thermostat (160 or 180 degree) can increase fuel and oil consumption, ring wear and emissions. On newer vehicles with computerized engine controls, the wrong thermostat can cause major performance and emission problems if the engine fails to reach the proper operating temperature. Cooling system leaks Loss of coolant because of a leak is probably the most common cause of overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.

Or maybe you were referencing Stewart Warners "tips" on thermostats which state :

Tech Tip #3 - Thermostats & Restrictors
Thermostats & Restrictors
We strongly recommend NEVER using a restrictor: they decrease coolant flow and ultimately inhibit cooling.

For applications requiring a thermostat to keep the engine at operating temperature, we recommend using a Stewart/Robertshaw high flow thermostat. This thermostat does not restrict flow when open. The Stewart/ Robertshaw thermostat enhances the performance of the cooling system, using any style of water pump.

Also, that's some...impressive numbers you've posted there, considering that no one is talking, even remotely, about water velocity/speed... If you'll "look closely" at my post, you'll see I don't change anything about the cooling system, other than path and the t-stat's cycle time.

I'm not going to argue with anyone about this stuff, as I've experimented with many engines to come to my conclusions - conclusions that are consistent with industry-wide standards. I personally could care less if you run a t-stat in your engine or not.

Southernman
 
Southernman,ill try disconecting the vacuum advance and pluging the port on the carb and see what that does.If this works where do i go from there and what does this mean.Issue 96 Sept 11 page 84 in the new Hemmings Muscle Machines book is where i read about taking the thermostat out.Check it out and see if you agree with his theory.Thanks
 
I took the vavuum advance off the carb and plugged off the carb port,set timing at 10 degrees and it seamed to work perfect.What does this mean.Is my vacuum advance on the distributer shot or what.
 
Do i leave port on carb plugged off.Nice car Tractorfix,i had a 67 Dart GT 340 4 speed but traded for the Duster.
 
dart gt said:
I took the vavuum advance off the carb and plugged off the carb port,set timing at 10 degrees and it seamed to work perfect.What does this mean.Is my vacuum advance on the distributer shot or what.
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I dont think your vac adv is shot. It is simply pulling the dist in to a condition with too much advance. There are ways to adjust your total vacuum adv on some vacuum canisters by sticking a small allen wrench down the vacuum port of the canister. On this website people have elaborated which years and distributors have that feature available.

I simply run our mostly stock 74 440 with the advance diaphragm not connected at all. It gets plenty of advance with the centrifugal advance only. I have tried the unit hooked both to manifold and to carb advance. Both variations made the car run poorly at mid range cruise. So, I leave it disconnected, tossed the hose and caped the open port on the carb.
 
Southernman said:
............I don't change anything about the cooling system, other than path and the t-stat's cycle time...................

I'm not going to argue with anyone about this stuff,
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You still have not explained "how you change" this path


I don't want to argue, I'm asking for REAL proof. I'm asking for an engineering reference (you SAID you are an engineer) to back up your claim THAT HAVING OR NOT HAVING A THERMOSTAT CHANGES THE PATH OF THE WATER FLOW IN AN ENGINE
 
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