Big Block Temperature

[cdushane]

I am getting mixed responses on big blocks. My engine is running around 210 to 220 when driving and then it seems to go down when at an idle. Some are telling me big blocks run hot and some are saying it could be the timing. I have checked the pump and put a new thermostat in but it still seems to be the same. Any input?

[Vegas69]

They don't run hot. You should be able to achieve 180-195 all day long this time a year if your cooling system is functioning properly.

[radrambler]

Chris

mabye the sending unit is bad ?
cause it sounds opposite of what should happen
my .02 worth

Tom

[chr2002ca]

Agreed. Typically a big block runs hotter during idle and cooler while driving, not the other way around, and it certainly shouldn't be running at those temperatures you mentioned. I have a big block and it rarely ever goes over 190 at idle and stays under 180 while driving. It could be the timing as one of your friends mentioned, however the timing and/or vacuum advance would have to be fairly off to produce those kind of temps.

1. Can you describe your fan setup(mechanical, electrical, type of shroud)?

2. Do you have aluminum heads, or an aluminum intake manifold, or ceramic coated headers, or an aluminum radiator? Each of those can help keep things a little cooler.

3. What temperature does your thermostat open at and have you verified that the water is flowing through your radiator when your water temp goes past the thermostat's temp?

4. What's your timing at idle and at 3000 RPM?

-Chris

[Blown353]

As mentioned, don't forget the tune and timing. Retarded timing will put a lot of heat into the heads and exhaust ports and therefore heat the coolant.

Not enough timing at cruise and light load is one of the "usual suspects" to check when an engine warms up when cruising down the road.

Still, need the rest of the cooling system details first before jumping to conclusions.

[cdushane]

Thanks everyone for all of your input but to answer some of the questions that were asked "I have no idea" (im retarded when it comes to motors). This is on the 69 I just bought and dont know much about the internals of the engine. Guess i'll take it up to the rod shop and see what we can figure out, atleast they'll know what their looking for.

[GregWeld]

Timing is critical... and it needs to be checked - and the rate of advance - and where that advance comes in etc. Any GOOD shop should be able to do this in about 10 minutes... Your Air Fuel ratio is also important... LEAN makes heat - and while most carbs are going to be fine - just driving around - it's another thing to just be aware of.. Particularly since you really don't know exactly what you have there. A good shop can check all of that out.

The heads you have on the motor - the chamber size etc will determine the timing - the cam - all of that... once you start messing with building motors and customizing - then it takes a good shop with a dyno to accurately set up the tune on your motor. Many of the new aluminum head designs need LESS total timing than in the "old days"... the flame front travels faster etc... and the gas today - blah blah blah. Too much timing and you can destroy a motor in a day - less even... so all this stuff is "important" to say the least. Even more important if you want to "get on it" -- and be able to drive without worrying about overheating etc.

[HRBS]

Chris... like others mentioned there are a few unknown elements to your engine. One is timing the other is compression and lastly components. If the timing is slightly advanded, you can retard it just 2 degrees from where your at and see about a 10 degree cooler temp. Also a big difference is that you have (i believe) iron heads. They retain heat and do not dissipate the temp as fast as alum would. Those two items will result in a 15-20 degree difference. A properly tuned Alum headed lower (9.5:1) compression BBC should run around 185-195 all day long.