Can you reuse head bolts Chevy 350 which have been blackend like rust?

It is generally not advisable to reuse head bolts that have become blackened due to rust, as they may not provide the necessary level of clamping force and may compromise the integrity of the head gasket seal.

Head bolts are subjected to high temperatures and stresses during engine operation, and the presence of rust indicates potential corrosion and weakening of the bolts. Reusing these bolts may increase the risk of bolt failure or head gasket leakage, potentially leading to engine damage.

For the safety and reliability of your engine, it is recommended to replace old, blackened head bolts with new ones when performing head gasket replacement or other maintenance involving the removal of the cylinder heads.