Big block running hot. Can’t figure out the issue

[nvrenuf]

Maybe check the radiator real good for flow. Possibly flush it for good measure?

What about belt routing, I've seen serpentine belts that could route differently than intended. Could the belt be driving the water pump in the wrong direction?

It would be a last resort since it would be pretty involved but maybe pull the water pump and compare it with another to verify the pump impeller is correct / reverse rotation?

 

[85K304SPD]

Show us some pictures of your set-up. Mainly the serpentine set up.

 

[Slooptin]

Maybe check the radiator real good for flow. Possibly flush it for good measure?

What about belt routing, I've seen serpentine belts that could route differently than intended. Could the belt be driving the water pump in the wrong direction?

It would be a last resort since it would be pretty involved but maybe pull the water pump and compare it with another to verify the pump impeller is correct / reverse rotation?

I’m planning on pulling it and taking the cover off to inspect.

Show us some pictures of your set-up. Mainly the serpentine set up.

Once I get home I can snag some pics

 

[squaredeal91]

I'm wondering if it's not the head gaskets covering up a water port? Total shot in the dark but it can happen.

 

[77Dmax]

It's probably not the cause of your ovwrheat issue based on your symptoms, but you should check your total timing and power time it. If you are running stock advance weights and springs you are leaving a lot on the table.

There is no reason to throw head gaskets at it at this point. It passed the coolant test and its not losing any. You'd also have running issues/misfires if you popped a gasket. Any possibility that the coolant is contaminated? I also wonder if the water pump is wrong, maybe boxed wrong? I hate to ask a dumb question, but is the pump spinning backwards? The wp pulley would be run by the smooth side of the belt if it is..

 

[Galane]

Did you check the bearing clearance with Plastigage to be sure they weren't too tight?

If there's nothing wrong with the cooling arrangement, a bottle of Redline Water Wetter in the coolant will help keep the temp from getting so high. Another thing to try is a special engine break in oil additive with molybdenum disulfide.