Getting ready to put a set of aluminum heads together. I've always believed in using a Heavy Duty intake and Severe Duty exhaust for marine use. But is it really necessary in a naturally aspirated application? Would a standard race valve be sufficient. End goal is 600hp BBC.
Opinions please.

IMO, YES.

Inconel exhaust valves, when do you need them?

Good valves aren’t that expensive and cheap valves aren’t that cheap. Go for some good stuff and don’t skip the inconel exhaust.

Not the place to save a few bucks in a marine engine build.

I'm right there with all of you. Just wondering if technology had gotten good enough of the race series of valves. Did get a rare chance to talk to an old acquaintance that builds offshore power for a living in Virginia. He said they use Manley Severe Duty in everything naturally aspirated. If it's got a blower they go to inconel for the exhaust.

Its always been a question. I have personally never had a valve failure BUT I use better inconel exh valves in everything. Im currently building a pair of 502 mpis with factory heads, same question, the factory uses Eaton Inconel exhaust valves BUT they are 2 piece , a hp500 and 500 efi with same heads uses manley inconel exh valves, more spring pressure, more rpms, more lift. Could I have reused the eatons, probably BUT I never have reused them with more spring, lift, rpms as a failure will make me go far backwards on a build when custpomers mad AF at me ! so as much as Id like to, would cost $$$ big if a head comes off. Smitty