Hey guys and gals

The 350 in my 71 has been getting a little too warm for me lately, I talked to a guy in Memphis last week about it when I was making a delivery. He drag races and he told me to bump the timing down a degree or two and he asked me what degree thermostat I was running and I told him 180.

The guy told me to get the hottest thermostat possible and I went to the local auto parts store this morning and got a 205, the truck has been running at about 210 on really hot days, 90 or above. do you guys think this will work? I bumped the timing down this morning 2 degrees BTC.

I'm running pre 1968 327 camelhump heads with 10:5 to 1 compression and I know the more compression the hotter it will run and it has a 3 core radiator. I haven't put the thermostat in yet, next week I go on vacation and am going to flush the system then put the thermostat in. I'll let you guy's know what happens.

Brian

Bumping the timing down may lower your temps. BUT the higher thermostat will raise your temps. Think about it. The thermostat does not open until it reaches its operating temp. In this case 210, so it will not allow water to circulate through the block until the temp in the block reaches 210. Get a lower temp thermostat to drop temps. A 160 I would suggest.

Hey Poltergeist, wouldn't a lower thermostat stay open all the time then?
I'm very confused 8O .

Brian

Actually, since cooling takes place at the radiator, the higher rated thermostat will allow the coolant to remain in the radiator longer. Also, keep in mind, the main purpose of the thermostat is to allow the engine to warm up faster, not to regulate temperatures.
Personally, I don't consider 210* to be hot.
Water boils at 212* at sea level. With a 50/50 mix of water and coolant, it will boil at 223* and with a 70/30 ratio, it will boil at 235*.
Under pressure in an automotive cooling system using a 13-16psi cap, will raise the boiling point another 40*-45*.
I run 180* thermostats in all my cars, including the LT1, during the summer, and a 160* in the winter. The 305's in my other Elkys tend to run around 190* year round.
The LT1 seems to run better between 200 and 210.
A 205* sounds a little overkill for your application.
I would first check your coolant, and then the radiator cap for seal and size.
Also, you didn't mention what type of fan and shroud setup you're using, whether you have an overflow tank or if the engine is boiling over.

The thermostat staying open would allow coolent to flow to the motor to cool it.

Water in the radiator being cooler really won't help the motor if it's not allowed to flow. Where is the water temp probe? In the block. True one of the main reasons for a thermostat is to help the motor warm up, but it also helps to determine what the operating temp of the motor is since it controls when coolant is allowed into the block to cool it. If you have a 205 thermostat it will not open until the water in the block reaches 205 and stays above that temp. As soon as the block cools to below 205 it will close, the water will be diverted back to the radiator. The water will not be allowed in the block, and the block will heat back up. So a higher thermostat will cause higher motor temps.

While I know your motor is not an LT1 like mine this example is the same. When I first got my motor going it had a stock 180 thermostat. The temp ran about 185 all the time. When I installed a 160 my temps dropped to about 165 in the morning and about 180 when it's hot.

Since your motor is suddenly running hotter are you sure there is nothing wrong with your water pump? A thermostat going bad will cause the same thing. But it seems like 90% of the time when I hear a motor is running hotter its the water pump.

Agreed, there is probably something other than the wrong size thermostat wrong with the car.
Also, not one to argue, but one who loves a good controversy, here are some links to very interesting articles and forum threads concerning the 160* vs 180* etc. thermostat controversy. Have fun reading up!!!

themostat article (http://performanceunlimited.com/illustrations/thermostats.html)

chevytalk thread (http://www.chevytalk.org/threads/showflat.php?Cat=&Board=UBB64&Number=201254&fpart=&PHPSESSID=)



water wetter poopie (http://www.redlineoil.com/redlineoil/wwti.htm)

The SBC runs better around 195 to 210. You have to have heat that is power. You don't have to have too much heat. If you are running an Aluminum engine or heads then you probably should go with a 195 thermostat year round. Get a good 3 or 4 row radiator. A HD stock radiator is fine. Aluminum heads need the extra heat especially in the winter time. So my advice for Aluminum heads is go with a 195 Summer and a 200/205 for Winter.

Most of the power as you probably know is produced in the heads for a SBC. Heat is power it is that simple. The better the temp the better the fuel vaporizes in the intake. The "Cooler" the "Air Charge" the better the fuel burns. So somewhere you have to have a happy medium.

I agree with Robert. Use a 185 to 195 thermostat. The Radiator is for cooling. Also if you have aluminum in the engine, heads or Radiator you will need an anode for the radiator. This keeps down electrolysis and your components will last a lot longer.

Just my advise FWIW.