[Formulajones]

I prefer cooler rather than hotter. But I build and tune things on the edge for the pump gas available (which isn't that great to begin with) and running the engine a little cooler helps me deal with that a little better.

I also prefer it cooler to help fight/avoid any possible vapor lock issues during the summer months. Especially on my stock mechanical fuel pump cars. The hotter the engine, the hotter things get under the hood. I don't like seeing anything remotely close to 200 degrees on any of my classic cars.

With proper jetting, timing, and a good functioning cooling system I have no issues with the cars running in the 180 range even on the hottest of days. Just yesterday it was 102 degrees up here and the Z never got over 182-183 degrees shooting it with a temp gun. That's with it's original 48 year old radiator. 11:1 compression on pump gas with iron heads, I'm not even going to entertain a hotter thermostat in this thing, lol.

My bird always stays in the mid 170's on days like this with a Griffin radiator. They are calling for 105 degrees up here today.

I think it's just going to depend on a lot of factors. If we had the gas quality now that we had 50 years ago, or if I weren't tuning/building on the edge, I wouldn't be so concerned with it.

[JLMounce]

Like the OP's my car really starts to come to life at around 195 degrees. I run a 180 stat and most of the time it sits at 185. On very hot days it will climb a bit to 190ish and as that temp starts to come up, pretty much everything about the driving experience starts to improve.

I'm running the FiTech efi on a KRE headed 455, so I attribute some of that to probably not running enough advance for my altitude and the 88 octane that I run through it. I haven't gone about changing it however as I have no desire to run the tune on the edge. I'll gladly give up 10-15 hp to know the motor is in a good margin of error.

If I ever change intake manifolds or need to do some maintenance to the cooling system, I'll probably change to a 195 stat however.

[68 Firebird]

had off today and went out early to tinker in the garage.
inspected weights in HEI and lube(they moved free and cap and rotor look ok)
adj initial timing to 16, that plus 20 mechanical put me at 36 @ WOT. still
have 12 from vacuum can on ported source. Curb idle increased after initial
was raised, so I reset curb idle back to 750rpm as it was earlier.
drove around for 20 minutes and yes car felt smoother and more responsive, immediately.
just like when I had come off that 75 mile freeway run. Temps stayed the same
at 185(fine with that). Detected no detonation, or missing.(my curve comes in slower)
Gonna leave it this way and enjoy!!!

Thanks

Gerry

[dataway]

I remember when I was a kid my father explaining to me, if my cooling system was working right, once it got up to temp, it should NOT run hotter on the highway, or cooler on the highway, or hotter or cooler ANYWHERE ... it should maintain the normal temperature in all situations within the range of the thermostat open and close range.

If temp goes above the normal range ... then something is wrong with the cooling system or it's not up to the task. If it goes below the normal range, then something is wrong with the cooling system.

Just like your house ... even if you have a REALLY POWERFUL AC ... it should still not get colder than the thermostat setting, nor hotter. If it does ... something is wrong.

[TheSilverBuick]

Originally Posted by dataway

I remember when I was a kid my father explaining to me, if my cooling system was working right, once it got up to temp, it should NOT run hotter on the highway, or cooler on the highway, or hotter or cooler ANYWHERE ... it should maintain the normal temperature in all situations within the range of the thermostat open and close range.

Exactly.

The best description of engine cooling I ever heard was:
"The radiator sets the maximum temperature and the thermostat sets an artificial minimum temperature. It just happens to be above the maximum."

Which basically means in a well functioning cooling system on a properly tuned engine that without the thermostat, or if its stuck open the engine temperature should always go down. If it's going up, then the radiator's ability to cool has been exceeded, aka the maximum is going up.

[TedRamAirII]

Newer car computers (ECM) monitor the time it takes from a cold start to running temperature, if it takes too long, or does not reach temperature in a certain time span, it turns the "Check Engine" light and it will have a code P0128. Usually caused by a thermostat stuck open, or the seal allowing coolant to flow when it is closed. With a properly running cooling system, the thermostat just dictates your running temperature.

[92GTA]

My 461 had a 160 thermostat when built. I went to a 180 and it burned less oil and ran much better at full temp. Then I changed to a 195f recently with a bad ass electric fan and a FlowKooler water pump, my engine really sings now. It loves the hotter temp, better mileage, better acceleration, better idle, burns hardly any oil, and just sounds more precision in operation if that makes sense. In my mind, I'm more comfortable running a hotter temp with full forged internals as well so I know everything is expanded optimally. I also like that with an electric fan, she gets up to full temp much, much faster.

I have 670 iron heads, 9.9cr, and run 91 octane (which I *think* is 10% ethanol here in CA?). I have a mechanical advance MSD RTR dizzy with 38 total timing, never have had a sign of knocking running 91. With 87, heck yeah. Even when 112f outside and fully heat soaked in traffic, my temp gauge never goes over 220f. I have my fan set to come on at 210 and off at 198. On average she runs about 205-215 according to the gauge.

I have a Holley 4150 with a 1/2 wood spacer on a Torker II so no heat passage and I have a divorced water crossover, I never have any hot start or fuel lock problems, ever. With the Edelcrap carb and performer intake I had vapor problems all the time, even when outside temp was only in the low 90s!

[Formulas]

Could of swore back in late 80's early 90's I bought a 205 thermostat but haven't seen them since