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post #1 of 12 (permalink) Old 04-28-2019, 06:05 PM Thread Starter
 
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Running too cool

I got a new 2.5in dual exhaust from pypes and now my motor is running too cool. The only change is the exhaust. Before if left idle it would creep up to 205-210 within 15min. Although it's only been 60-70F outside so far, it only gets up to 180F and that's after I've driven it for 40min and let it idle for a while.

As soon as I start driving again it instantly goes back to 165F-170F. Never any higher through town or 55mph highway (2000-2200rpm).

The coolant is a touch strong of a mixture and is an inch or two over the stock cold mark in that 1968 brass radiator. I did install a flowkooler impeller pump with a really close gap between the pump and plate ~0.015".

Any thoughts on why or how to get this back up? Are my mufflers too free flowing?
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post #2 of 12 (permalink) Old 04-28-2019, 09:02 PM
 
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I got a new 2.5in dual exhaust from pypes and now my motor is running too cool. The only change is the exhaust. Before if left idle it would creep up to 205-210 within 15min. Although it's only been 60-70F outside so far, it only gets up to 180F and that's after I've driven it for 40min and let it idle for a while.

As soon as I start driving again it instantly goes back to 165F-170F. Never any higher through town or 55mph highway (2000-2200rpm).

The coolant is a touch strong of a mixture and is an inch or two over the stock cold mark in that 1968 brass radiator. I did install a flowkooler impeller pump with a really close gap between the pump and plate ~0.015".

Any thoughts on why or how to get this back up? Are my mufflers too free flowing?

Do you realize you have a thing called a thermostat? This can regulate engine temps. From what I read, I would say you have a 160 degree T-stat. My opinion, it is perfect. But if you insist throw a 195 T-stat in it and see what the temps do.
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post #3 of 12 (permalink) Old 04-28-2019, 09:07 PM Thread Starter
 
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Of course. I have a 195 F thermostat. I verified opening temp when I installed it 2 summers ago. Maybe the thermostat is stuck. I'll replace it and see.

Do you use a lower temp thermostat? I know many, including cliff ruggles, insist on a 195F thermostat to ensure a proper A/F mix.
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post #4 of 12 (permalink) Old 04-28-2019, 09:58 PM
 
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Of course. I have a 195 F thermostat. I verified opening temp when I installed it 2 summers ago. Maybe the thermostat is stuck. I'll replace it and see.

Do you use a lower temp thermostat? I know many, including cliff ruggles, insist on a 195F thermostat to ensure a proper A/F mix.

OK, you did not state you had a 195 T-stat. Yes it is possible that it may be hanging open. It is also possible your gauge may not be reading correctly.

Before pulling the T-stat, you might consider one of the laser temperature guns sold at any auto parts store. They are fairly accurate and you can shoot at different points on the cooling system. My '73 Plymouth temp gauge constantly indicates the engine is near to a boil over in stop and go traffic. Has a huge radiator and the car was never puking any coolant into the overflow - which it should have. Laser temp gun proved my coolant temp was actually very good and my gauge was the problem.

T-stat choice is in my book one's preference or opinion. I read that your oil needs to reach a certain temp to evaporate any moisture in the oil. Hmmm. Might be a case for that if you do short trips around town and don't run the car hard. The 195 T-stat is also mandatory if you live in the snow belt if you want your heater to blow hot air to keep you warm or defrost the ice & snow off your windows.

Never heard the A/F mixture argument - new one on me. Seeing there is an exhaust crossover that goes under the carb and is typically left unblocked, there is a lot of unregulated heat that never sees coolant and no doubt would change A/F ratios as exhaust temps constantly rise and fall based on the heat of the day, under hood temps, and the heavy right foot that exercises combustion heat which is whisked away out the exhaust and its crossover under the carb.

A cooler running engine can lessen the chance for detonation or engine pinging, allows more timing advance which can equate to addition power, and can allow for a richer fuel mixture which also can equate to additional power.

Now if you are talking newer and contemporary autos and trucks, that is a whole nother ball game. Todays cars are engineered and designed to run efficiently at hotter temps and it also reduces emissions. But they also use a lot of aluminum which absorbs and dissipates engine heat. Cast iron holds heat.

My opinion - I like and use the 160 T-stat just to keep engine temps down - almost in the range you shared which in my experience would be perfect numbers. Nice and cool going down the road, 180 in stop & go traffic without worry of boil over, cooler oil temps, and when I open the engine up I am not looking to listen if the engine is pinging because it is heat soaked. But, with any high performance engine/car, I don't baby it and burning rubber and wide open throttle blasts are my joys - so I want a cooling system that works and takes all the heat I put into the engine.
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post #5 of 12 (permalink) Old 04-29-2019, 10:31 AM
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I'm with Jim. Been using nothing but 160 T-stats for 40 years in these cars. It's hot where I am, and I like my cars to run 180-220 as much as possible. Have never had a Pontiac that actually would run at 160 degrees.....and that's too cold anyway for thermal efficiency. You want the engine to run hot enough to be efficient and burn off condensation in the oil, and you want it cold enough so it does not ping.
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post #6 of 12 (permalink) Old 04-29-2019, 03:32 PM
 
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Really you want to be like Elvis...cool!

I am with Pontiac Jim and geeteeohguy,..I run a 160 degree T-stat in my 461 stroker. An hour on the highway at 70 will give me about 185 degrees, around town stays at 160. I use a flowcooler WP as well and a tight impeller clearance.

As for AFR, I am real particular on that and run wide and O2 in each exhaust and a meter to read in both on dash. I run with the exhaust crossover open, keeps the intake hot for instant vaporization of the mixture, yet the engine is cool, but that is a whole mother discussion.

As far as condensation the oil temps are hot and water evaporates at various temperature not only boiling at 212 degrees. The water, in the form of sweat that evaporates off your arm is not boiling at 212,... yet there it evaporates. Clouds are water vapor and so is fog, none of those are at boiling temperature. But a good oil filter, I only use Wix and a good PCV system together will evacuate the water vapor and the blow by and crud.

I was down at Butler Performance they had supplied and cut my short block, super crew, I asked one of the guys what thermostat they recommended. He said they put a 160 degree thermostat in every......every....engine they build. Now you should see some of those engines they have. I believe they no hot Empl can cause detonation and cooler running is better.

I also use an ME Wagner PCV valve and catch can to keep crankcase vapor, blowby and crud to a minimum. It pulls a vacumn of 1 to 3 HG 99% of the time,...you average cheap 5$ PCV valve maybe pulls vacumn 10 to 30% of the time.

So if you are cool, my recommendation is to stay cool and work your AFR with a good carb and an AFR meter on or off the car.
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post #7 of 12 (permalink) Old 05-02-2019, 09:17 AM
 
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The rating of the thermostat only determines when it opens -- the cooling system, ambient temps and engine load determine how hot the engine runs. At least that's how I understand it...
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post #8 of 12 (permalink) Old 05-02-2019, 09:48 AM
 
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Totally agree, if you run a 195 thermostat and the car runs at 180.....it is either stuck open, or running so cool that it does not reach 195.

Often the heater core acts as a radiator because it is just a mini one, and with flowcooler WP and tight impellers and four row large tube radiators you can get em to run cool, you do't want detonation and pinging and when superheated cylinder walls and compression causes that mixture to detonate prematurely.

I have a snorkel air cleaner and it drops on each side of the carb inside of the engine. Colder air is denser and effects the mixture, I am not a believer that it gains more HP, certainly not on a street car, and not into running jams for outside air. I used that ainly for hood clearance, but I have checked the temos at the snorkel and usually about 10 or 15 degrees above ambient air...so if it is 80 degrees maybe 95 at snorkel......

once in my intake the exhaust crossover is open and it is real hot, vaporizes instantly, because hey it is only in there for micro seconds passing thru...so the mixture in the cylinder is already hot and vaporized, engine temp may be 170.......not a factor in AFR

thermostats begain to open at rated temp and even can a bit earlier, as wax pellets are not that super exact.....once running down the road it is all the other stuff in your cooling system that determines your running temp.

By the way, we all talk constantly about the coolant temp, but take a temp gun or thermo gun and after a good run take it out and shoot it around your engine compartment, Carb temp? Fuel lines? both bowls? intake runners? air cleaner? exhaust manifolds? ........even the coil and alternator, see what you get.

if you check at the fender just inches away, you will see it is close to ambient......

If your is boiling from heat soak you may find the problem.................these temps are not coolant temps.....




if your fuel lines and carb are real hot...your gas may be boiling in the lines and bowls causing hard starts hot......the distaillation curve on summer blend gas is about 140 for E-10 and 170 for pure gas......if you are up in those ranges on carb and fuel lines might need some heat shielding!
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post #9 of 12 (permalink) Old 05-02-2019, 08:48 PM Thread Starter
 
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That definitely make sense. Thank you all for the input. I'll try a 160F thermostat and see how things go.

I've always replaced the thermostat while draining coolant. Can you swap the thermostat without draining coolant?
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post #10 of 12 (permalink) Old 05-03-2019, 08:48 AM
 
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Partly, but it just a mess and nobody does that.....if you are going to open it up...for a new thermostat put in fresh coolant.
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