Ideal Operating Temp

[70SwingerGuy]

So Ive been reading on this lately, and I always figured my mildly built 340(Eddy heads- carb- intake, MSD, mild cam, headers) was doing good running at 160, climbing to around 180ish in more stop and go on warm days. But, Ive been reading that 160 is too cold. So my question is two-fold, what is the ideal running temp for my engine, and what trouble can be caused by it running too cold at 160?
Thanks FABO

 

[toolmanmike]

180-200 is good in my book. With a 15# system it doesn't boil over until about 245.

 

[RustyRatRod]

It's all in the tune as they say and it's true. IMO, engine temp is something to experiment with and see where it runs best. Especially non stock engines. You're out of the factory specs wheelhouse, so the factory temp thermostat may not be optimal.

 

[remytherat]

trouble can be caused by it running too cold at 160?

Oil can get dirty faster.

 

[70SwingerGuy]

It's all in the tune as they say and it's true. IMO, engine temp is something to experiment with and see where it runs best. Especially non stock engines. You're out of the factory specs wheelhouse, so the factory temp thermostat may not be optimal.

Thanks @RustyRatRod @toolmanmike @remytherat .
It actually runs really good, except for it fouling the plugs a bit too much, Ive just changed to a hotter plug, and will be looking at carb and timing more in depth soon as well.
Shes in the bodyshop right now getting repainted, so cant do anything until shes home

 

[Oldiron440]

You might verify that the temp gauge is correct…

 

[70SwingerGuy]

You might verify that the temp gauge is correct…

Brand new Autometer and sending unit

 

[RustyRatRod]

Brand new Autometer and sending unit

Well, now you know better than that. NEW and GOOD don't have the same definitions. So, if you don't have one get an IR temp gun for 20 bucks and verify.

 

[70SwingerGuy]

Well, now you know better than that. NEW and GOOD don't have the same definitions. So, if you don't have one get an IR temp gun for 20 bucks and verify.

yes thats true, good point! I guess Ive always equated Autometer with high quality stuff, so I just assume that it is accurate. Been meaning to pick one of those up too, Ill make sure and do that

 

[Demonic]

180* minimum, 195 preferred for mild builds. The factory went to 195* in 1969. If it runs too cold like 160, the moisture inside takes too long or never vapors off on a short trip.

 

[Sterling]

My opinion is that it depends on what fuel you are using. I was told years ago, unleaded fuel needs more temperature, that is one of the reasons newer cars run hotter. If it was me, the temperatures you posted seem fine to me, as long as it is running fine and the spark plugs look good, I would leave it alone

 

[Newbomb Turk]

160 is as cold as you should go on a street engine that needs to run a heater.

There is more to dropping coolant temperature to 160 than just changing the thermostat. It needs to be thought out from the beginning and then done. If it’s just Willy Nilly dropping the temperature then you are most likely killing power.

All gasoline (alcohol is worse) require vaporization to burn. Liquid gasoline (or alcohol) doesnt burn.

From the time the fuel leaves the nozzle (booster) until the plug fires ALL the fuel needs to be fully vaporized. If it’s not then the engine burns more fuel than it needs to and the oil gets dirty.

The oil doesn’t get dirty from lack of temperature. It gets dirty because you are pumping raw fuel through the engine.

Your cooling system should be capable of maintaining WHATEVER temperature the thermostat is in almost all conditions. If it won’t, find the weak links and fix them.

I run my engine at 160. On 100 plus degree days it is at 160 all the time. The ONLY exception is at traffic lights. It will climb to 180 and stay there. And it has to be a long light or a freaking train to make it do that. Once moving it goes right back down to 160.

If you are running an intake manifold that doesn’t have a heat crossover or you have it blocked, or if you have a cold air intake (like an air gap or Strip Dominator) and you are trying to run 160 degrees you are just wasting fuel.

You need the heat to vaporize the fuel and you don’t have it.

You can fix that issue by using a quality annular booster. And that’s a must if you are running your engine temperature at 160.

If you aren’t 11.5:1 compression on pump gas you don’t need to be at 160 unless you are willing to tune for it. And I don’t mean just change jets. You will need to recalibrate the carb to run that cold and still make power while not burning fuel like a super tanker.

 

[70SwingerGuy]

@Newbomb Turk @Sterling @Demonic Thanks again for some great info. According to what everyone is saying, and what Im seeing in my engine, I think it may be time to verify temp and swap out the 'stat for a higher temp one.

 

[RustyRatRod]

All yall saying 160 is too cold, let me propose this. Get your shower water to 160...IF it will even get that hot. Now stand there and look how much steam is comin off that water. Still not convinced? Then get your nekkid azz under it.

There are many variables here. First, as always is said, this is tune dependent. Secondly, it's also a time thing. Get your junk runnin 160 and take a five minute drive for ice cream or wherever over and over. Not good. However, if you're like we are, the closest town is about 25 minutes away. That's plenty of time to get any nasties out of the oil and if you don't think any moisture gets evaporated out, you gotta nuther thing comin. Lots of yall are forgetting about another thing called OIL TEMPERATURE. You may have regulated coolant temp to 160 or 170, but oil temps routinely get higher than 200.

 

[413]

Cracks me up when the Six pack tuning questions come up and many swear it needs to be 195 or it will never run right. LOL

I like a 160 stat and if it's 40 degrees outside I cover up part of the radiator so it will get to 170-180. But in the hundred degree heat it's nice having the 160 in there.

Why put a low limit of 195 in summer heat and traffic? Nonsence

 

[fishmens67]

Why put a low limit of 195 in summer heat and traffic?

It really doesn't matter during summer heat, the engine will only cool as much as the cooling system is capable of, your 160 stat will open and remain open during the summer if the system isn't up to snuff.
180 is a good compromise for the average system.

 

[4spdragtop]

Our 340 runs 190-195 at summer temps.
If you get a temp gun DONT get Can Crap, I have one that reads WAY off. Reading 230* i was stressed lol. Used better quality o.e from work and it was 195*

yes thats true, good point! I guess Ive always equated Autometer with high quality stuff, so I just assume that it is accurate. Been meaning to pick one of those up too, Ill make sure and do that

 

[70SwingerGuy]

Our 340 runs 190-195 at summer temps.
If you get a temp gun DONT get Can Crap, I have one that reads WAY off. Reading 230* i was stressed lol. Used better quality o.e from work and it was 195*

Good advice Steve, thanks!

 

[CFD244]

My mild 340 auto runs 180* (Stewart Hi Flow T-Stat) in the summer rock steady and drives great.

On a side note though......Took it for a ride at 0* C and it barely reached 180* in an hour of highway driving at 2500 rpm. LOL, looking into that one first thing next summer

 

[AJ/FormS]

I run my Eddy headed 360 at 207

 

[fishmens67]

I run my 451 at 179.2, sometimes it gets up to 179.9. lol

 

[RustyRatRod]

I run my 451 at 179.2, sometimes it gets up to 179.9. lol