The ones I purchased new were good to go OOTB. Zero issues, run the last 24 years. No issues. The ones I just worked, 20 or so years old. A quick hit on the valve seat, no problem. Valve stem heights on MY heads were fine. Valve stem heights on the pair i worked on, a bit off. I can not do a whole lot of work in my basement. The owner is fine with it. I say OK, he took them home and is happy as hell.
Purchase quality material. Do a search or ask the fellas here that port/work on heads what they use and why. The price oof OK valves and a good set can be a few bucks, but inthe end, you'll forget the price as the miles of smiles pass on by. Buy crap, spend twice, the previous smiles of saving money will flip into a frown.
