bigger valves and hardened seats

[80-383]

What are you guys doing about exhaust seats when cutting for bigger valves in big block 781 heads? Would an additive work or do seats need to be installed? I have seen where water has been hit when seats were installed with oversize valves. One machinist told me once that if you are not towing it should not be a problem to let them go. This will only be drove on the street. Any opinions would be appreciated.

 

[tubage]

I have 820 heads. They have about the same size runners but mine have smaller 113cc chambers. I had my machine shop cut 2.19/1.88s and hard seats. No problems. Mine is a street engine also. I felt like it was the proper way in the end. Chris