What type of exhaust valve do I need to use? a Severe Duty or inconel

NA... or blown?... if blown you better go with the inconel... the severe duty stainless will work... but if the grind isn't perfect... adios to the valve...

Please define a "perfect grind" for those of us that might not know what your definition of that is.

Do a search there is more.

http://www.offshoreonly.com/forums/s...threadid=67779

A grind where the entire face of the valve that touches the seat is symmetrical and can transfer heat to the seat...if the grind isn't symmetrical... it will transfer heat unevenly and will distort... the only way an exhaust valve dissipates heat is when it is closed and the amount that transfers up the stem into the guide... if the guide is sloppy of the valve isn't ground symmetrically... it won't transfer enough heat and will "tulip". Do any of you guys remember sodium filled valves?

Yeah, Ford liked the sodium-filled valves for a while (mid-sixties). And the sodium liked the inside of the motors when they cracked too.

If have a turbocharged or blown motor you should use inconel. The exhaust temperature of the valve can get over 1300 degrees and at that temperature regular stainless steel valves won't take it. If your just carbed or EFI, a quality well installed stainless steel valve on a good seat will do just fine. What does quality mean, a valve thats 21-4N , EV8 stainless steel or better. A valve thats concentric and a forged one piece valve. All good valves made today are made in Argentina. That goes for Manley, Ferrea, Rev, Superflow, etc.
Raylar

* gasp * made in Argentina????

Yep! More US jobs hit the dumps with NAFTA!
Raylar

I went to the Manley site... there wasn't anything about valves being made in Argentina... but it doesn't surprise me... next they will be made in China... China... China.... China.... maybe Mexicans will start going to China.. that seems to be where all our jobs are now...