Technical SBC 350 - How hot is too hot?

Thanks I will check what psi the 53 Chevy ran and get a cap rated for that radiator.

I have a coolant recovery tank shown in the photo in post #57.

 

Thanks for sharing that. I noticed the motor temp a bit different after changing the coolant and that's what caused the initial alarm.

I was hoping to make a shroud at some point since it didn't have one but prior to changing the coolant it seemed to be ok for the most part. I will inspect and make sure there is no air in the coolant system.

 

Has the probe always been in the head or recently moved from intake to head?

 

It was always in the head. I also was told it had been calibrated but I don't know what that means.

 

Ok Couple things...
First thing is first. Get the temp sensor out of the head and into the manifold. Combustion temps are going to be significantly higher than at the manifold or at the rad itself. I was told this when I was going to hook up a temp guage years ago and I have seen guys get bent out of shape about temps when the temps are higher at or beside point of combustion (ie right at the cylinder)

If the temps don't come down significantly then pull the rad and have it cleaned by a rad shop (they will boil it and clean it) it might have to stock core in it. Usually when you get a rad re-cored they will add extra cooling tubes that will help with cooling efficiency.

Got a couple extra bucks put an Allstar Aluminum Rad in it. One for a 55 chevy. They are cheap and your temps will significantly come down. I have a couple buddies that have done this and it is almost a direct fit. I run one also. 180 all day moving 190 in traffic with electric fan.

Jay

 

There are lots of ways to spend money on stuff and worry about it....whether you need to or not, that's another question. Probably not.

 

The previous owner said that the radiator is an original 53 Chevy radiator but it was recored a few years ago at Cal's Radiator in San Diego. He says he thinks it has a 4th row in there and it should be pretty solid with the new core it got.

 

the problem is the tanks, the surface area is pretty large. Multiply pounds per square inch by number of square inches, there's a lot of force pulling the tanks apart with a 13 psi cap

 

The radiator should have been inspected first. Not simply 'assumed' that it was clean, and not clogged, dirty, etc.; Problem now is finding a radiator shop that will remove the top and bottom tanks, rod out the vanes, and solder the tanks back on. All will contract to do this, only some will do the work. Most 'boil the radiator out' in their hot tank, then a quick black paint job. This can loosen up some dirt and slag in the core, but as it cools, the grit stays inside, causing a 'still clogged' condition.
Ask me how I know. (I even had to mark tanks and solder fillets so I could tell when I picked it up that it had been disassembled. ONE radiator shop did what they said! 3 didn't.)

Be sure what you're working with. And whom.

 

I would take 55gasser's advice and invest in a radiator designed for v8 and modern pressure. Cheap insurance.

 

Exactly.

First and foremost let's get the temp sensor out of the head and into the manifold and then lets see where you are first.
Jay

 

Thanks, sorry to ask stupid questions but would a 72 Chevelle motor intake manifold require drilling and tapping a hole to accommodate the temp sensor?

 

If you want to start out right; go to Ebay or Harbour Freight and buy a infra red thermal heat gun for about $20 so you know the gauge is correct or off . If your cheap like me find a friend who has one in his tool box and have him read for you.

 

The manifold on your engine? look at it and see. Are there any plugs in the front, where the coolant passage is, around the thermostat housing? they need to be in that coolant crossover area.

You don't really need the temp gauge in the intake, you can leave it in the head. It doesn't really matter exactly what the numbers are, as much as knowing when the engine is going to boil over.

These guys are getting you all paranoid

 

There are several preformed shrouds available as well. Trim to fit variety, based on radiator dimensions.
Keep in mind the fan and shroud will only help when your idling or rolling fairly slow, under 25 or so.

I prefer to run 25/75 or so coolant to water ratio, a 180 T.stat and it should be good to go.

The main factor for what temp is acceptable is boiling point, then detonation comes from too hot as well. Cracks in parts and gasket problems happen in extreme cases.
If your cap is good, system is sealed well, the coolant mix shouldn't boil until 250 approx if your using a 14 psi cap.

 

I added a gauge to my intake. And it reads about 15 to 20 degrees cooler there.
Pat

 

I'm with Jim (squirrel) on this. Lippy

 

Amen to checking the timing ! Start at 6° and go from there. If you have a distributor like an MSD then make sure you have the Silver springs in it to slow down the advance. Timing at 14°, light advance springs and a 195° t-stat id a sure fire mix for detonation and heat. In my experience in a car of that weight, 10° was the sweet spot. cam profile and compression should also be considered. JMO Hope it helps

 

Thanks I remember asking on a different thread and many said 14 deg was a good starting point. I have an MSD Streetfire with an advance spring kit and I installed the lighter springs. I don't hear/feel any pinging noise at all.

The 180 deg stat change is something I will definitely do.

 

Why do you want to change the thermostat?

 

I bought the car 2 years ago and don't know it's history too well. I thought it couldn't hurt to change the thermostat anyways? I've changed the coolant, brake fluid, differential oil, ATF fluid, motor oil, etc since I didn't know the history of the car.

 

Take it out, put it in a pot of water on the stove, put a thermometer in the water, heat it up and watch it open.

 

Wait! I know, Squirrel, I know! 195* just HAS to be too high to start out with!

Truth be told, my 350 ran 195 with a 160 thermostat, now runs 180 with a 190 thermostat. (also 'stove-tested', a MUST nowadays.)
But, my radiator is new, so we have a clean system. (30/70 on Glycol/H2O...)

 

I run my blower motor with a 195 thermostat with an electric fan and relay on at 160 warm at 195 no water wetter and no shroud never goes over 195 40/60 antifreeze one time at the strip got 200 but temps were over 100f and rarely on the street below freezing no heater 31 chev coupe with lots of drafts.I would stay mec fan and add a shroud do not run straight water...

 

I might as well add my 2 cents: Your Automatic Transmission cooler is covering 1/4 of you radiator surface so if you relocate it to where it is not in front of the radiator, you may gain a couple degrees cooler.....altho people run them there all the time. You may have a lean condition which would add to heat / can be checked by looking at plugs. I would definitely try a new 180 TStat with a small hole drilled in it but first boil it in a pot on the stove to make sure it opens before installation. When you drain the radiator; shine a light in the filler hole.....if you see 4 water passages wide; then it is a 4 core and should cool a sbc fine..... if you see brown junk around the passages; then it needs cleaned. How many blades does that fan have and is it steel?

 

Thanks those are good points. I can't recall how many blades the fan has but I will check. It is the kind that flexes and I know the pitch will flatten under high rpm if I'm not mistaken?

 

Please take a picture of your intake manifold. It is what the carburetor sits on. we will be able to tell if it has a hole for the temp Sensor.

 

Thanks. I can take photos tomorrow when I go in the garage. For now heres a photo from when I was working on getting the driver side cylinder head out.

 

This is good to do. Pull the coolant housing off and check and see if there is a thermostat. If there is. test in a pot of water that you bring to a boil. use a Turkey thermometer in the water to see where exactly it opens. don't know if this question has been asked yet.
What kind of gauges are you running. Sometimes a cheap set will not read properly. I usually test the sensor at the end of the gauge to see if the gauges are correct.

 

Where is the photo?