Brand: Automotive Racing Products (ARP)
If you knew the massive amounts of energy that the harmonic damper had to absorb just at idle, you'd never trust an OEM bolt again! ARP has engineered their harmonic balancer bolts with incredible 190,000 psi tensile strength to provide the ultimate in reliability. The included large-area washer is 1/4" thick to deal with the clamping force. The 12-point head is extra-tall to take a deep-well socket so you never have to worry about stripping the hex.
This kit fits the small-block Chevy V8. The bolt has 7/16-20 threads with 2.47" under-head length. The head has a 1.25" base OD and takes a 13/16" 12-point deep socket.* (This is the middle socket size of the three kits offered by ARP.) The head measures 13/16" tall with 7/16" of socket engagement. The washer measures 2" OD.
* Note: The ARP website currently lists this bolt as taking a 3/4" socket, which is not correct. The ARP catalog correctly lists it as taking a 13/16" socket.
