People still think that straight water is fine for car cooling systems; this is a big mistake. There are multiple different reasons to use proper antifreeze in your Bugeye. Antifreeze lowers the freezing point of the liquid inside your cooling system, preventing cracked engine blocks.
Additionally, you need the anti-corrosion properties of antifreeze. The photo above was taken down inside the thermostat recess in a 1275 head that was run on water, perhaps for a long time. Freezing is not the issue in this case… the engine shown is in Florida. But you can see a remarkable amount of corroded metal has collected under the thermostat, all because water was used without antifreeze.
We were able to vacuum it all out (the pieces all seem to have collected in the pocket under the thermostat) and there should be minimal lasting damage. But please don’t make the same mistake. Regular old green 50/50 antifreeze is all you need to keep your corrosion down and your engine happy!