Is it normal for a 440 6 barrel 70 cuda engine to get really hot after a 15 mile drive?

You might wish to have the cooling system and radiator flushed, but how hot is awful hot. Sometimes running a bit lean can make an engine run hot. Also, if the radiator is not the correct one for the engine, you might consider getting one with additional cores. Have you rebuilt the carburetors if they were immersed? The center carburetor is the one you will want to really check out most carefully. If memory serves, the other two open when you let the ponies run. Have you removed the heads? If the engine was immersed, the oil galleries may be compromised with oil/water foam after running some. This would be a good opportunity for a valve job and new lifters which may also have been damaged if water got into them. My experience is pretty much all GM and it was an old 409, but I figure the basics are about the same.

How hot is “really hot”? Any internal combustion engine is going to get as hot as the cooling system will allow. Assuming you have a properly functioning, properly sized and intact (pressurized) cooling system, that can be (depending on environmental factors, the condition and usage of the engine, etc.) somewhat higher than the boiling point of water, or > 212°F. That’s normal, but it’s still pretty hot to a human!

If the cooling system isn’t the right one, or if it’s compromised by plugging in the core, short on cooling fluid, blocked from air circulation at the grill, etc., or if there’s a problem with the lubrication system, then it can get even hotter, to the point of failure.

Do you have gauges to tell how hot it did get? Are they trustworthy? Or do you just have a dashboard idiot light that didn’t light up – and is there a failure in that circuit that simply prevented it from lighting when it should have?

Again, how hot is hot?

That is an engine worth saving. If it were me, I would probably pull it and do a proper re-fit. This may be the only opportunity you get. You didn’t mention, is it an automatic or manual transmission? It may have been submerged too. Drain all the fluid and take a chance on it with fresh fluid, or have it looked at while the engine is out. These are the heart of the restoration after severe water damage and probably the most expensive. Best not to skimp and be left by the side of the road.

Floodwater plus carbs..

Personally, I wouldn’t have even tried to crank it as there’s no telling what was between the air cleaner and the intake valves… though you’ll probably find some of it in the cylinders and crankcase now. And likely some scratches on the cylinder walls and bad rings to boot.

Fortunately, a good restoration often involves a complete engine teardown anyways, and if you weren’t before, you pretty much have to now. Take it from somebody who has dealt with flood-damaged cars.

You may have ruined the motor (temporarily) as some have pointed out.
So what? If you’re restoring the car, rebuild the engine (or have it done). It will be a better engine than it ever was if you do it right. Materials science, fabrication and machining have come a long way since 1970 (and that car was actually assembled in early 1969 from 1968 parts, of course.)

Anyway, I don’t recommend trying to diagnose and repair it. Write the engine off and rebuild it. If you got sand in the block you will have buggered the main bearings. Big deal, get a billet crank. If you didn’t get sand in the block then you probably got water in it, which you’ll find out when you check the oil. Regular water in oil sometimes just looks like beads, but you’ve probably got “peanut butter” in the block (water mixed with engine oil at high temperature makes a gross emulsion.)

There’s also bad things that could have happened in the head, but again, who cares? At minimum you will want to do a head job, and install hardened valve seats (and better valves while you are at it) so that the engine will run on unleaded fuel.

By the way, if you ran the engine on unleaded fuel, then yes it’s normal for it to run unusually hot. Check the oil and the coolant anyway, and don’t run the engine any more. Tear it down and make it super. Have fun!

I agree with the rebuild. It’s what I would do in the restore process anyway.