I've searched and read every post I can on overheating, and haven't come to a good conclusion yet...here's my setup:
1980 Camaro Z/28
Engine rebuilt 7k mi ago, stock except for intake manifold, cam (don't know details), carb, air cleaner
SINCE then: new spark plugs, rad. hoses, radiator/cap, fan/clutch, water pump, thermostat (180), stat housing.

I just did an oil change this las weekend. Cooling system has no leaks, and the radiator/fan/pump are the stock models.

I live in SoCal, Mojave Desert, and every day my car is cooler than 220 only because I keep it under 3000RPM. If I go much more than that, it will heat up to redline quick enough.

The car will idle for about 10 minutes at 180, then start climbing to probably around 190...

I just checked the timing, and it's right at 8.

This is the only car I have down here, the truck, motorcycle and porsche are all up in Washington state, and it's not feasible for me to get them down here; so I need to fix this.

It usually gets to over 100 outside here, but I have PLENTY of engine space, fender vents, entirely new cooling system (not junkyard, NEW, every piece)...but there's got to be something warming up my engine.

Does anyone have any idea what I should chase after next to cool down my 350? It's frustrating doing 60mph on I-10 (65MPH limit) and being passed, when I'm in a Camaro with the T-tops off!

Do you have a fan shroud on it? Next what lower rad. hose are you running. It's possible that the lower hose is sucking shut and cutting off the water flow. Try to find one with the coiled spring wire inside it.

You timing is alittle low, but not the cause of your prob. Bump it up to 12-14* and it will idle smoother, more throttle responce, better power and probbly 5* cooler

Did you test the thermostat before installing it by boiling it in water with a thermometer to see exactly where it opens and closes? Have the radiator cap tested too as they fail over time and cause overheating problems.

Yes, I have a fan shroud.

The lower rad hose I'm running is stock according to NAPA, I specifically asked about the spring reinforcement, and they said it wouldn't make a bit of difference, and didn't know where to even find one. The hose collapsing was my first troubleshooting step; top and bottom were getting sucked closed.

I've been under the hood right after a drive (not fun when the engine's at the better part of redlining) and played with the throttle and watched the hoses, seem fine.

One of the pages here say that the timing should be at 8, but I'll try 12-14 and see what that does, I guess; couldn't hurt. My worry was that the timing was too far advanced (father's suggestion).

I haven't tested my thermostat, but it's brand new, I've watched my gauge and can see when it opens, same with my other new one (195* stat). I opted for the 180* this time around.

When the engine's hot, if I release the lever on the rad cap it releases the majority of the system pressure, and coolant goes into the reservoir.

I think today I'm going to try running the car a bit with no stat in it and just see what the car does.

.:Edit:.

I just removed my stat then watched the flow of water through the radiator cap, plenty of water flow. This was a suggestion from my Dad, who's done it to numerous cars when he was younger. It did exactly what I expected: it only took longer to overheat.

I really am totally lost now, I've gone through ALL my ideas.

I would try a 195 stat and see if it helps. It will allow air to remove heat from the radiator for a longer time period.


I'd move up to a four row radiator if that doesn't cure it. When I switched to a big block my three row wouldn't cut it, no matter what I tried. Switched to a four row and now everything is cool even at 110 degrees outside.

Good luck,

Marcus

I've got a 195 stat, it didn't help at all either. It wasn't until I put the new water pump on the car that I could even consider going anywhere at a temp below 220 with the 195 or 180 stat.

I've thought about going for a 4 core radiator, but I just paid $160 for mine and can't quite justify ANOTHER new radiator yet.

What kind of radiator, fan, shroud, water pump, do you have?

may try an extra electric fan

I have an '80 that I rebuilt the engine about 23 years ago and it has about 10,000 miles on it. It's been sittin' most of the time. A couple of years ago I got the bright idea of putting in a gear drive and chroming stuff under the hood. I bought a chrome high volume water pump off of ebay and put in a new 3 core radiator. On hot days in Cent. IL. it runs about 210 no matter what thermostat I have in it. With the AC on, it creeps up to about 220. I always remember it running about 180 (maybe my memory is going!). I contacted the guy I got the pump from and he recommended a restrictor plate, that the water was moving to fast to cool (?!?!). I found in the Classic Industries book a thermostat for high volume water pumps. It said something about high volume pumps can hold the thermostat closed (makes better sense than what the other guy said). Anybody have any experience with this?

How is your transmission operating? If the trans is giving you problems this will cause heat into the engine also. Do you run a torque converter clutch?

How is your transmission operating? If the trans is giving you problems this will cause heat into the engine also. Do you run a torque converter clutch?


4 spd.

It sounds like you've checked out the cooling system. I don't think thats your issue. If it was the water pump, you'd get poor flow, if it was the fan, it would behave at speed. That radiator should be able to keep that motor cool.

Timing might be the issue, but you'd have other problems like backfiring and sneezing. Is it surging/bucking at speed ?

My bet is you've got a problem with the intake/carb and are running very lean. Check for vacuum leaks, make sure the carb is good and adjusted properly.

But what makes me REALLY thing it's a intake problem is the new manifold. I'd pull the manifold, and get some new gaskets. BEFORE you put them on, put a light ( 1/16 inch smear ) of silicon around each intake port on the head then lay the gasket on the head, do the same for the manifold side. Run your usual bead at each end of the manifold. Lay the manifold on the new gaskets, but DON'T torque manifold down until the silicon sets up ( about 20 minutes ). Then torque to spec and let the silicon cure for another few hours before firing the motor.

I fugyre you are running antifreeze. Try a 160* t stat and possibly a larger radiator, maybe aluminum 4 core. While I've never had to deal with such extreme outdoor temps, my operating temp dropped significantly (200-170) by changing t stats from a 195-160. I also changed rad caps to a 16# which helps. I pressure tested my old one and found it only held to about 14#. The new one holds for 16#. Just because yours is a 15 #'er, it may be defective. Biggest thing is you need air flow through the radiator. Good clean fins and a properly operating fan properly fit into the shroud should be pulling a good amount of air through the radiator.

Stock gauge?

You might want to try a different gauge/sending unit just to be sure the gauge is still accurate.

My sender in the head on my bbc said it was that hot. I got a gm sender and moved it to the intake now the hottest it gets is 180 (where the fan turns on). I would get a temp at the hose with a heat gun or themometer. Can you hold you had no the upper hose?

Does the car have (or did it have) AC? Sometimes the condenser fins get blocked or there is a buildup of crud between the condenser and the rad that you cannot see unless one or the other is removed. Also be sure the shroud is well sealed to the rad. Good luck.

If some of these other suggestions do not work out, you can put a big block radiator in there. I have one in my '71 with a 350 and it never goes above 180 no matter what the condition is.

Like I've said, COMPLETELY new cooling system: all my rad fins are good, there's no AC condensor anywhere.

I'll try adjusting the carb, and do that work with the intake manifold; and maybe a 160 stat as well. If I find time. This is my only car down here, so it's hard for me to work on (not like at home, I could always jump in my other vehicle if I needed more parts, and had all the tools I needed in my garage).

I contacted the guy I got the pump from and he recommended a restrictor plate, that the water was moving to fast to cool (?!?!).

I've heard this exact argument AGAINST taking out the stat completely, which is what I tried. The car takes longer to overheat, but also cools down a bit quicker.

use a 16lb radiator cap. 2-row radiator is pushing it. is your clutch fan kicking on? is it half way in/out of the shroud? +1 on the guage being off. borrow a pyrometer from someone and point it directly at the radiator. drill a small hole in the thermostat to let air through as they arent really drilled well from the factory.

For a bbc, I would make sure you have a 4 core radiator unless it is aluminum... You are chasing ghosts if it is a 2 core...

I've got a 3-core radiator.

The fan is all the way in the fan shroud.

I'm not sure I understand "is your clutch fan kicking on?". When I'm under the hood, revving the car with the carb by hand the fan's working just fine.

I have had a problem like this before, and one day a saw a wisp,(for lack of a better word) of steam come from driver side cylinder head next to the fire wall.AS i looked closer I could see small bubbels coming fromthe head gasket area. I did not have any oil in the water or water in the oil. And the exsuast tester,the one you test for exsuast in the rad,never detected any. But i did have the exact same problem you had,As long as i drove slow speeds it didnt over heat. When the head came off it was clear it was blown,avery small passage from the water hole to the back of the gasket. Dont know if this is your problem,but the syptoms match perfectly.