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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 197 on September 23, 2007, 07:01:24 PM

Title: Thermostats?
Post by: 197 on September 23, 2007, 07:01:24 PM
I changed my thermostat in my 454 from a 195F to a 180F. Because It would get kinda hot.

I herd that I will get worse gas mileage with the 180F and less power. Is that true?
Title: Re: Thermostats?
Post by: jays2w87 on September 23, 2007, 07:46:20 PM
I would wait for one of the bigger guys to answer you but, That sounds crazy, And if its true its measured in a lab. Nothing you would ever notice.
Again, see what someone else says but, I have done a few motors and never heard of that.
As far as power, well if the engine is cooler its going to run more efficient. I had a small block ford motor a while back and it seemed like when it was up to temp for a while it didnt move quite as good as when it ran cooler. No Fuel issues though.
I have to be honest, If your running a big block does gas even matter ?
My last 4 wheeler I ran 38 inch tires and everyone asked about gas milage. My answer was ... I have no clue. I put gas in it when its empty, then I drive til its gone .
Title: Re: Thermostats?
Post by: 197 on September 23, 2007, 08:02:47 PM
My answer was ... I have no clue. I put gas in it when its empty, then I drive til its gone .


Ya, I have owned the truck for about 3 years and havent figured the mileage out yet.  ;D
Title: Re: Thermostats?
Post by: VileZambonie on September 23, 2007, 08:07:35 PM
The 195 Tstat brings your engine closer to optimal temperatures. An engine running cooler loses more heat energy from the heat of combustion to the cooling system. So in a sense you are wasting thermal energy. Since you have a HEAT engine you are wasting that heat energy. Most modern engines run 205-220 before the cooling fan is energized. On the flip side cooler cylinder head temps reduce the risk of detonation. But if your engine isn't overheating or detonating then stick with the stock Tsat. If you do a lot of towing and heavy romping around keep the 180
Title: Re: Thermostats?
Post by: 197 on September 23, 2007, 08:16:35 PM
So the 195 would be better? Its a daily driver.

It was dieseling when I would turn it off. And it would get a little hot when It was just idling at lights so I changed the thermostat and I have been running 93octane. And its stopped dieseling dont know if it was the gas or the thermostat.
Title: Re: Thermostats?
Post by: jays2w87 on September 25, 2007, 07:16:55 PM
I would say Fuel issue. Try running some cleaner thru. My resolution is 15 gallons of gas, 2 stp treatments (same time) Along with either hi test fuel or a bottle of octane booster. The combo of 3 works awesome !
You will nitice a difference once you burn thru that mixture. While burnin thru it it runs fine . You wont notice anything.
If you look on the shelf you'll see big doller treatments, Dont Buy them. They are all the same. I have experimented with my car , my wifes, a few others I have owned, the best result is the 1st thing I explained. I usually do it once a year. I'm over here in the north side of CT almost in Mass. We get snow and crap weather so I do it going into the winter. Gets all the crap out of my fuel prior to freezing weather.
Title: Re: Thermostats?
Post by: 197 on September 25, 2007, 07:22:44 PM
Ok, thanks for the tip!
Title: Re: Thermostats?
Post by: 75 C20 on September 25, 2007, 09:12:30 PM
So the 195 would be better? Its a daily driver.

It was dieseling when I would turn it off.
you might want to check your timing
Title: Re: Thermostats?
Post by: VileZambonie on September 26, 2007, 02:38:24 PM
For dieseling check your timing, make sure your choke is working, do a top engine cleaning and then change your oil.
Title: Re: Thermostats?
Post by: Lt.Del on September 26, 2007, 07:20:47 PM
If it is dieseling real badly, I'd go ahead and retard the timing just a tad.  (Turn distributor clockwise a hair).  See if that stops the run-on after turning the engine off.

Another option is to go with a cooler spark plug.  It seems as though the heat in combustion chamber detonates (without spark--ignition off) the fuel left over.  It is kind of embarrassing---turn the key 1/2 off while the truck is still in DRIVE.

Title: Re: Thermostats?
Post by: 197 on September 26, 2007, 07:55:55 PM
It stopped dieseling after the change to 93 octane. Why would that cause it?
Title: Re: Thermostats?
Post by: VileZambonie on September 26, 2007, 09:28:25 PM
Becaue higher octane fuel is less combustible at lower temperatures so it doesn't ignite as easily. Putting in 93 is fixing the symptom not the problem.
Title: Re: Thermostats?
Post by: 197 on September 26, 2007, 09:35:59 PM
So the problem is the timing? Correct?
Title: Re: Thermostats?
Post by: Lt.Del on September 27, 2007, 11:11:28 AM
Could be.  It's just an idea.  Doesn't hurt to try it.   When driving uphill or under a load, does the engine seem to "rattle" some from the valves?  Having 93 octane will disguise this somewhat.  To test this, I'd use 87 octane.  If it rattles some, I'd do as mentioned, retard the timing some.

Quote
And it would get a little hot when It was just idling at lights

You mentioned that at idle, it tends to get hot or overheat?  I'd check your clutch fan (if that is what you have) or flush the radiator.  How old is your water pump?  If your cooling system is not decipating the heat correctly, it will remain in the engine and contribute to diesling due to the heat. 
Title: Re: Thermostats?
Post by: Captkaos on September 27, 2007, 11:34:15 AM
Do you know where your timing is set right now?
Title: Re: Thermostats?
Post by: VileZambonie on September 27, 2007, 01:24:17 PM
Set the timing to spec. If you are running 87 octane and it's pinging get some top engine cleaner and get rid of the carbon. Make sure you are not running a hotter than stock plug. Is your EGR functioning?
Title: Re: Thermostats?
Post by: 197 on September 27, 2007, 03:48:34 PM
Could be.  It's just an idea.  Doesn't hurt to try it.   When driving uphill or under a load, does the engine seem to "rattle" some from the valves?  Having 93 octane will disguise this somewhat.  To test this, I'd use 87 octane.  If it rattles some, I'd do as mentioned, retard the timing some.

Quote
And it would get a little hot when It was just idling at lights

You mentioned that at idle, it tends to get hot or overheat?  I'd check your clutch fan (if that is what you have) or flush the radiator.  How old is your water pump?  If your cooling system is not decipating the heat correctly, it will remain in the engine and contribute to diesling due to the heat. 
No rattle under load or uphills.

And for the temp, when idling it will go up alittle but it wont get to hot and its never overheated.

What do you suggest for a topend cleaner?

Also we retimed it last spring when we replaced the cap,rotor,wires,plug,carb... and I beleve its a 9 or 10.

Whats a EGR?
Title: Re: Thermostats?
Post by: Lt.Del on October 02, 2007, 10:35:31 PM
(http://www.delbridge.net/egr.jpg)

Title: Re: Thermostats?
Post by: 197 on October 03, 2007, 08:09:42 PM
Whats the egr do?
Title: Re: Thermostats?
Post by: okuma on October 03, 2007, 09:47:53 PM
I USED TO HAVE A 305 ON A CAPRICE CLASSIC. I WOULD ALWAYS PUT 93 OCTANE, BUT WHEN $ CRISIS CAME I WOULD ONLY PUT CHEAP 83 OCTANE. I GUESS THE CARB. GOT USED TO GOOD GAS, BECAUSE I DID EVERYTHING TO IT AND IT WOULD STILL RATTLE AND STAY ON A FEW SECONDS  :-\ AFTER I WOULD TURN IT OFF! :D
Title: Re: Thermostats?
Post by: VileZambonie on October 03, 2007, 10:30:55 PM
EGR = Exhaust Gas Recirculation. It take inert gas (exhaust gas) and redirects it into the combustion chamber to reduce the temperatures of combustion effectively lowering oxides of nitrogen (NOx). NOx is produced when combustion temperatures exceed 2500F