Stock SBC 350 Crate Motor valve chatter under load
Pull a valve cover and look to see if the lifters and rocker arms are getting oil. Watch out if you rev it too high oil will squirt all over the place. Be sure and check it at idle and giving it some gas pedal. How long have you had them AutoZone sparkplug wires? Fire it up at nighttime completely dark. Check for spark around the boots and where they plug into the cap. Next time it comes time to replace them try the AC Delco Part No. 9608U $62.99. These wire last a long time. They are 8MM wires with a lifetime warranty too. Order them online and pickup at the store for a 20% off.