3.4L 3.1L GM 1999-2005
The 487 casting comes with either a
8mm rocker bolt or a 10mm rocker bolt hole. The 170 come only as a 10mm rocker bolt hole
Note: The torque on the 8 mm rockers rocker bolts calls for, 120 in lbs. (10 ft. lbs.) plus 90 degrees) This is only good with new rocker bolts ,that only come with the entire rocker assemble.
If your not replacing all the rocker bolts each
time your torque them down, a maximum torque of 10 ft.lbs. (No 90 degrees plus later revised to 30 degrees
) or you will
pull the threads.
Care should be taken not to torque a rocker with the valve in a open prosition as this can pull the threads as the spring pressure pulls the thread before the bolt is fully seated.
If you buy 2 head of a pair the second head is shipped free.