These hardened, parallel-ground chrome moly washers are perfect for use under the head of cylinder head bolts. The 7/16" ID and 7/8" OD match FF1600 head bolts perfectly*, but they can be used for any purpose.
The special "insert" design fits into an oversized hole to help support and protect the material around the hole. This protection is especially critical in applications such as aluminum cylinder heads, where torquing the head bolts could force the aluminum to collapse into the hole. Holes which see radial forces (such as motor plates) will also benefit from these hardened inserts. The hole must be bored to 0.529" ID (13.4mm) to accommodate the insert. Black oxide finish. Sold in packs of 10.
* Although Ford never used washers under the head bolts from the factory, many engine builders prefer to use them. They are required with the FF1600 Aluminum Cylinder Head (Part No. 162-01-Alum).