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friends 401 buick in old hot rod

Discussion in 'The Hokey Ass Message Board' started by chubbie, Nov 23, 2009.

  1. chubbie
    Joined: Jan 14, 2009
    Posts: 2,314


    a good friend of mine is building a 33 chevy pick-up rod, 401 buick duel 4 carbs, switch pitch 400 trans. he wants to do things right!!!!
    do we need hard seats on the exhaust valves? or better said... has any one ever had trouble with unleaded gas and old school heads???? I've been told you can run 60,000 miles with out a problem, the next sooth sayer say naa, you have to put in hard seats... I say NO!!
    I did the search thing...some said you'l ruin a buick nail head w/ this modification, HELP..

    next issue any help on what the buick head needs for port and polish, or general "clean up"

  2. holeshot
    Joined: Sep 18, 2009
    Posts: 1,519

    from Waxahachie do you know their not hard one's now. a seats are not that expensive. well compaired to heads! right? and i would sure like to hear people how know about the modification THING! how in the world will adding hard seats ruin these heads?...POP.
  3. czuch
    Joined: Sep 23, 2008
    Posts: 2,688

    from vail az

    I've allways heard about hardned seats. Going back to the 70's when real gas went away. I've never heard of anyone doing it outside of when doing a valve job.
    IO'd run it.
    Could be all wet but......................
  4. For a short time driver cast is OK for a while, but when you go to rebuild do the hard seats.

  5. I put about 150k miles on an old SBC runing no-lead and non-hardened seats. Never heard a peep out of it. I'd run it as is.

  6. sideshow01
    Joined: Nov 5, 2004
    Posts: 96

    from Dirty Jerz

    Thought this wasn't an issue in Nailheads... Original factory setup is safe with unleaded fuels, no?

  7. TagMan
    Joined: Dec 12, 2002
    Posts: 6,103


    The Nailhead casting has an extremely high Nickel content. No need for hardened seats. In addition, the water jacket is very close to the seat area and many blocks have had to be junked when they were milled out for seats and struck water - DON'T DO IT!!
  8. Fitysix
    Joined: Sep 17, 2006
    Posts: 308

    from Md.

    As Tagman said....Nailheads don't need them, in fact I was recomended from doing it as alot of nailheads have been ruined by installing hardened seats. Don't do it.
  9. zman
    Joined: Apr 2, 2001
    Posts: 16,588

    from Garner, NC

    Don't do it... period. DO NOT let anyone talk you into it.

    To close to the water jackets, more than half end up ruined. And they don't need them.


    And let's not forget the valve geometry takes relatively low spring pressure as well. The biggest drawback is the ruining of the heads when you hit water.

    Again... do not do it.
  10. got any pics? got a soft spot for early chevys with nailheads...
  11. Actually you dont need both hard seats and hard valves. Lp engines use stainless exhaust valves. Just one or the other. What happens is carbon will stick to the valve or seat and gets pounded. A hard valve with a 3 angle seat wont let carbon stick easily.
  12. I had new seats put in my heads, they needed them. It was also done very carefully by a very experienced machinist. I've also run nailheads without re-seating and no problems, but I've also always used premium fuel and when I can, E0.

    Jeff, you are an early chevy nailhead powered lover, aren't you....
  13.'s a sickness....BTW, i'm cleaning off some of your old 32's steering pieces(my dad got) and rebuilding them...

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