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Hard exhaust seats

Discussion in 'The Hokey Ass Message Board' started by sunbeam, Feb 12, 2014.

  1. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,330

    sunbeam
    Member

    Hard seats yes or no? I've went with idea that if it's not a high GVW or tow vehicle they are not needed.
     
  2. fsae0607
    Joined: Apr 3, 2012
    Posts: 871

    fsae0607
    Member

    Lots of threads about it. General consensus seems to be only if you run the engine hard. If not, then don't worry too much about it, like say if you have a stock engine and you cruise around.

    Of course, if you're rebuilding an engine to put in your "HOT ROD", you're gonna run it hard, right? :) Have them put in.
     
  3. papastoyss
    Joined: Apr 9, 2009
    Posts: 195

    papastoyss
    Member

    Seems like if you're going to the trouble & expense of replacing valve seats, why not use the best? Once & done!
     
  4. Halfdozen
    Joined: Mar 8, 2008
    Posts: 623

    Halfdozen
    ALLIANCE MEMBER

    I know a guy who's put over 100,000 miles on a 302 Jimmy without hard seats, running on unleaded gas. He adds a bit of two stroke oil to each tank of gas, has never had valve problems.
     

  5. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,330

    sunbeam
    Member

    Run it hard for what 20 seconds at a time.
     
  6. fsae0607
    Joined: Apr 3, 2012
    Posts: 871

    fsae0607
    Member

    Cumulative effects. Besides, isn't it the standard to install hardened seats now whenever you have machine work done on heads?
     
  7. some say yes , some say no......i think you need them

    [​IMG]
     
  8. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    It's a good idea to do the seats while the heads are being done, but I would just put a tip here having done a bunch of these type resto's in the past!

    In the beginning we had special seats made up for the SBC heads to our own specs which included a different radius on the outer corners of the inserts. We made them with an .093" instead of the usual radius. This helps avoid cutting into the water jackets at the seat corners.

    We made the cutters match the radius for installing the seats.

    We also use .218" on the depth as opposed to the more conventional .250" deep, again, it's just that much safer!

    One thing I would mention, never try to put o'size valves PLUS the seat inserts, most times it will not go. If it had a 1.500" valve stay with that size!
    Most of these jobs can be done safely but the inserts have to be configured for the job. Early Pontiac's are another head that have "thinner" material at the exhaust valves.

    Thanks, Gary in N.Y.

    P.S. Today we machine the conventional seats in-house using our own blades instead of doing any "special-orders". Saves time on the jobs. In the photo you can see the larger radius and the blade used to machine them.
     

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