I have had a set of Ductile iron rockers on my car for 30 years. race car. has a 640 lift cam in it now. I am building a new engine now and I bought new set of Harlem sharp rockets for it. We will see. I hope I am not disappointed.
We have a set of HS that have been in use since the 70's. The 1st three engines ran any where from low 10's to mid 11's They have been on my brothers GTX since 2002. Street strip car 500-1000 miles a yr.
