ARP Head Bolts Be Aware!!!

September 10, 2010


ARP produces some of if not the best fasteners on the market, but we have run into an issue from time to time especially with cast iron heads that some of the lengths are too long, most commonly the medium length bolts under the valve cover on the ends of the heads. This issue can also be caused by decking of the block and heads so checking to make sure there is adequate room to stretch the fastener is critical.

When using ARP head bolts we recommend to do a trial run on each one without the washers installed to make sure the head of the bolt contacts the cylinder head. By doing this you can be assured that there is adequate room to stretch the fastener once they are installed with the washers. If you find the bolt head doesn't contact the cylinder head before bottoming out, an easy solution is to add a second hardened washer (must be a hardened washer!!!) which are available from ARP as well as other manufacturers. Shortening the bolt/s is another solution but we prefer the additional hardened washer. Be sure to use ARP Moly lube on the threads and under the bolt heads for proper stretch/clamping.