I have a 1973 454 Vette and it keeps over heating. I was wondering what temperatures other BB cars run at?

Everything is New: Motor/trans/radiator/electric cooling fans/180 stat/water pump and the damn thing still over heats.

I was told that maybe the builder put the wrong head gaskets in it because certain BB had cooling passages in the heads? So if the wrong gaskets are in it could be blocking those passages. Does that sound correct?

 

Just a little more info please. Are you reading too high on your gauge or are you actually boiling over? And what are the current ambient temps in your area?

 

First of all if you're using a wrong temperature sender for your gauge it will show higher than normal temperatures so make sure you have the correct sender. You can buy the correct sender from any of the Corvette-only vendors like Eckler's, Corvette Central, Rik's, etc.

When does it "overheat"? When driving in stop-and-go traffic or on the freeway at cruising speeds? The dual 11" electric fans often provide adequate cooling at slow speeds but fail miserably at higher speeds because of reduced air flow thru the radiator so which is it? Low speeds or higher speeds?

I really doubt you have a head gasket problem because all the big blocks use the same style/configuration of head gaskets with the holes in the same locations.

 

This summer has been pretty hot and humid, so 80/90 degrees in the evening while cruising isn't uncommon.

It's reading high on the gauge in the car. It hasn't ever boiled over-I've heard it bubbling near the thermostat housing though. I've had a laser temp gun in the car before and i'm not sure where to point it at to see how hot the damn thing is actually getting.

 

What does the Temp gauge say? 190-210 is normal.

 

It goes clear to 250. Then sometimes it comes back down to the 200 range-it's like it takes a while for the stat to open up. Just makes me nervous as all when everything is new on it. I will say though the heater core is out of it so the coolant isn't going in there.

When I had an electric water pump on it and a 160 thermostat in it it was worse. Someone told me that the the coolant is running through the motor/radiator so quickly that it's not getting time to cool down in the radiator.

 

You need to determine if it is really overheating. Do you still have the 90 degree bypass hose that connects the front of the intake manifold to the top of the water pump? That hose allows the coolant to circulate thru the block and heads prior to the thermostat opening so that hose MUST be in place; especially as you have removed the heater core that also allows coolant circulation prior to the thermostat opening. Aim your IR gun at the metal thermostat housing or at the metal radiator inlet neck; never at the rubber hose.

Are you absolutely sure you have the correct temperature sender for your gauge? In the past I have found most "overheating" problems are just a result of a wrong temperature sender.

 

That's a myth.

 

Mine runs pretty consistently at 210 even in the high heat we had on the weekend here (90f and humid). It did spike to 230 when I turned the AC on in traffic. I have 2 electric fans, I think the second one only comes on with the AC.

 

Assuming your gauge readings are correct, what's your timing set at? Insufficient advance will heat up a big block quite easily.

 

Does your car have it's front lower chin spoiler attached?

Makes a big difference in cooling getting that air up there.

All seals in place around the radiator?

First thing I would do is boil the stat to make sure it's working properly.

I recently got a bad one,drove me nuts.

 

Tell the factory engineers that

 

If any factory engineers actually said that I would them them it's a myth as well.

 

OP: Is the engine temp climbing rapidly and then suddenly it drops for no apparent reason? If so you have an air bubble in the system.

 

My 73 BB TH400 is all original under the hood. On a 80-90 degree day, in town or at highway speeds my temp gauge reads around 190. 100+ degree day about the same. I recently got caught in bumper to bumper traffic on a day that was 110+ and my gauge showed temps of 230 to the red. It would slightly drop when I got moving and once I was free of the traffic I noticed normal readings of 190- 200. Do you have a shroud on the radiator? If not install one. Make sure the spring is in the lower radiator hose and make sure the hose is not collapsing. Drill a 1/8" relief hole in the thermostat to allow a little water to bypass when its closed. As stated above, check your timing and thermostat. If you have the front license plate on, try removing it with the backing plate, then install a center grill in its place to allow more air into the radiator.

 

The highest temperature I have ever seen with my '71 big block was 220 degrees on a 105 degree day with the A/C on in stop-and-go city traffic. As soon as I was able to pick the speed up the temperature dropped to 210 degrees and stayed there until I got back home.

 

From the '71 Owners manual (p.21):

During normal operation, gauge will indicate around the 210F mark. Hard driving, heavy traffic with stop and go, or prolonged idling in hot weather will produce a gauge reading around the 230F mark. Whenever gauge reaches 250F, stop engine and determine cause of overheating or reduce speed permitting engine to cool.

 

remove your thermostat completely, then see if it overheats. that will tell you of capacity, clogging, collapsed hoses, air dam, timing, etc..and other issues, mythical or not.

 

[QUOTE=73 454;1595645068]I have a 1973 454 Vette and it keeps over heating. I was wondering what temperatures other BB cars run at?

Everything is New: Motor/trans/radiator/electric cooling fans/180 stat/water pump and the damn thing still over heats.

I have a NOM 454 in my 68 convert. With a 4 row aluminum radiator, electric fan, stock belt-driven fan removed, 180 thermostat the car runs at about 180-190 when moving on the highway. Stopped in traffic it goes up to 220, but recovers when the car starts moving. Note I have the little by-pass hose removed so I can put the temp sender on the front of the intake manifold, but have a thermostat that allows coolant to flow even when it is closed. Get one of those high flow ones for your car. The stock temp sender position near the exhaust is the absolute hottest place on the engine, so temps there will be higher. Temp on the intake manifold reflects the average temp of the coolant just before it goes back to the radiator. If it gets overheated here, you really do have a problem. You may also want to verify that you do not have a lot of air in the coolant system. With the engine cool, carefully check the level at the thermostat housing, which should be the highest point on the engine. Note I live in VA where it often gets over 90-100 degrees

 

If the coolant was circulating too fast through the radiator, wouldn't it be circulating too fast past the heads & block, removing heat extra fast also?