Overheating Big Block

[fleming23]

Well that set up is certainly better than what I had in my mind. The flaps can certainly play a role going down the road but the car should be able to maintain normal operating temperatures while idling. There was a thread on Team Chevelle by Brandon from ATK Engines with a similar looking shroud and he was having very similar issues with his electric fans. I only briefly paid attention to his issues but I do remember him taking a hole saw and making holes in his shroud so air could freely flow through the shroud at highway speed. I'm not sure that was his entire issue but when the shroud is solid like that it basically creates back pressure and does not allow the air to move across the radiator like it should. You would think it would just tunnel it through the fans but that is apparently not the case....

Is your issue isolated to while driving or can you sit at idle for an extended period without overheating? I'm still not sure about your overflow at 190 issue. The only logical thing there is the cap. I would definitely put either a 180 or 160 degree stat in the car with a bypass or a small hole drilled.

The temps are coming down so it makes troubleshooting these issues a bit more difficult as these cars will run cooler by default. Let me know if the car can idle without overheating. Also, how is the timing set? Do you have vacuum advanced and if so is it on full manifold vacuum or ported?