how can I get my mid 70's pontiac 400 motor to run cooler?

Question

it wants to run at about 220 i've just put a cam in it and put on a high flo water pump also have a 14 inch electric fan on it along with the mechanical fan as well but it still runs hot doesn't over heat but runs to hot

I'm running a new 4 core rad and a high flo water pump with a 160 therm two fans a mecanical and a add on electric fan also a trans cooler switched to a march serpintiene belt conversion as well

Answer 1

first get rid of 160 t/stat and put in a 195 the coolant is moving too fast too be cooled. it appears you have gone a long way to cure this so i must ask is the engine new or newly rebuilt? are there enough hours on the engine for proper break in? if re-bored are the piston to bore clearance's correct for the pistons you are using?have you set the ign timing to cam makers specs? are you certain that the cam timing marks were properly lined up when the new cam was installed did you degree the new cam in upon installation?
if you address all of these questions honestly the problem will disappear.

Answer 2

you know when I was working for Pontiac Mazda dealer back in the old days this question came up again and again. Do you have a real direct reading temp gauge screwed into the left head? water is susposed to be hot out of the top hose. What is the actual temp of coolant inside the cyl head. Early smog engines you know if yours is one. Ran hot for a reason to lean down the quadra-jet carb. Exhaust gas Recirculation then was needed to keep from pinging it self apart. Yours sounds normal keep a correct good cap on it and make sure there is a good recovery tank to return coolant when the engine cools down. Any air in system might cause a boil when the motor is switched off after a quick run. Be careful switching to cold thermostat just get a failsafe t/stat. You'll want heat next winter and not monkeying around coolant when it gets cold outside.

Answer 3

Most cars in my shop today run 210. If you HP the car 10 degrees isn't going to hurt a thing. it isn't "TOO HOT"
You could put an 18 or 20 PSI cap on it if all components are good. This will allow it to build up more pressure and therefore it will cool better as the pressure is popping off at 15 right now. The water will not boil at 220 under pressure of 15 or more PSI

Answer 4

Did you bore the block? Aluminum, or cast iron heads? ( aluminum doesn't like that kind of heat constantly)
Fan shroud in place? What kind of car? Are the fans pushing or pulling in the right direction? With a 4 row, and all of those fans it should run 180-190. Put a 180-195 thermostat in it, and make sure you have a 15lb cap. The coolant doesn't have a chance to cool off with the thermostat you have in it.

Answer 5

try using a bigger radiator, also if the fan is electric, ditch that and try to find one that bolts directly onto the camshaft pulley. Also, make sure that there is nothing on the front of the radiator and flush it out real good. That should help drop the temp 10-15 degrees. Another thing you may want to try is changing the thermostat. Instead of running a 220degree thermostat, buy a 180 degree.

Answer 6

Change the thermostat, or put it back in if someone suggested you remove it. So many folks believe that the thermostat does not do much, but it alone controlls the flow of water through the radiator, and therefore controlls the amount of time the water spends in the radiator for cooling. It is not much use to have high flow if the water does not have time to cool. Alternativly, increase size of radiator.

Answer 7

If the engine is new, I would look at the radiator and check to see if the tubes are clogged. It may need to be rotted out. Secondly, I would consider a new radiator with a minimum of 10 cooling fins per square inch. if the engine is not new, the cooling jacket may need to be cleaned out. The engine timing must also be right on. A thermostat is important, since it slows the water down and allows it to cool the engine.

Answer 8

You should not ever run a 160 degree thermostat UNLESS it's spec'd by the manufacture. A thermostat that cool is basically staying open.

Answer 9

Try a larger capacity radiator if you are concerned. But personally I would not worry,220 is not really that abnormal. Shop owner ASE master tech for 16 years.

Answer 10

the Siamese cylinder 400 needs to run hot,any cooler than the 195 degrees and it will run ragged,put the correct thermostat back in ,195 degrees,the weaker thermostat isn't holding the water long enough to exchange the heat to the water,its the water, ...........its is moving to fast.