LT1 Opti drive seal

[LeMarky Dissod]

I don’t think I could compare your description here with my question because in your case the water (coolant) was present in the water jacket, even though you had no pump function.
So even without a pump, the fluid in the head would absorb some heat. My question assumes there’s no water or coolant in the head.

I see your point - also, my heads were iron, not aluminum.

I was just wondering what a safe run time might be for an LT1 aluminum headed engine with “no coolant” might be.

Assuming the engine is truly cold, I'd not idle-run any engine with no coolant for longer than 120secs, regardless of block and / or head composition.