Opinions needed on OEM 246 Exhaust valves | FerrariChat

Opinions needed on OEM 246 Exhaust valves

Discussion in 'Technical Q&A' started by Pantdino, Mar 22, 2012.

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  1. Pantdino

    Pantdino Formula 3

    Jan 13, 2004
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    Jim
    #1 Pantdino, Mar 22, 2012
    After 3 days and 94 views but no responses on the 246 forum I'm moving this to the Tech forum in hopes of some opinions.

    My engine was rebuilt in 1986, 17K km ago, using OEM valves at a Ferrari dealer.

    What was the frequency of broken / dropped original valves?
    Had they improved the design by 1986?


    Thank you

    Jim
     
  2. Monza 456

    Monza 456 Karting

    Sep 15, 2005
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    Craig Nelson
    #2 Monza 456, Apr 2, 2012
    Never heard of one dropping a valve in the 31 years I've been working on Ferraris
     
  3. fastradio

    fastradio F1 Rookie
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    Apr 26, 2006
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    David Feinberg
    #3 fastradio, Apr 2, 2012
    I've got a Boxer piston sitting on my desk, as a paperweight. It has a welded up hole in it from a broken sodium exhaust valve. This happened almost 30 years ago....
     
  4. davehelms

    davehelms F1 Rookie

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    #4 davehelms, Apr 2, 2012
    I have (3) 308 engines, (1) 330GTC head, (1) 365GTB/4 Factory Comp. engine and head, and a few pistons laying about... all with varying dents and holes.

    Keep the revs to 5K and the concern is reduced. Every example I have ever come across to date, came apart at very high revs, likely valve float range. If it happens there, it will happen everywhere in time. Want to hear them scream? Change the valves.
     
  5. alberto

    alberto Formula 3

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    Alberto
    #5 alberto, Apr 2, 2012
    You'd have to change the valve springs to eliminate that float problem first, before they scream. Any idea what the RPM is where valve float sets in? Just curious.
     
  6. davehelms

    davehelms F1 Rookie

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    #6 davehelms, Apr 3, 2012
    Post redline, these were very healthy engines, at least in a few instances. I am only speaking of examples I have personally dealt with. Net rumor has dozens of examples but I refuse at accept anything I have not dealt with myself in these regards... the first liar never stood a chance.

    Given the limitations with the fuel we now have and the designs of these old engines, redline operation just makes noise but little extra power. If it comes apart to freshen, then it can be built to utilize the entire rev range with little risk.... and new stainless valves used in place of the Sodium ones. To say there is no risk with the old valves is wrong, there is. I belive, at least at this point in time, the risk can be managed... in time that will change.
     
  7. malcolmb

    malcolmb Formula 3
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    Malcolm Barksdale
    #7 malcolmb, Apr 3, 2012
    Dave, my Daytona dropped an exhaust valve at 3000 rpm in third gear, just loafing downhill into la Jolla. Metal fatigue eventually happens I guess.
    Malcolm
     
  8. mikeyr

    mikeyr Formula 3

    Jun 17, 2004
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    Mike Rambour
    #8 mikeyr, Apr 3, 2012
    my 206 is still running on its original valves, I only worry about dropping a valve as I hit the redline, the rest of the time I am enjoying the drive.
     
  9. davehelms

    davehelms F1 Rookie

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    Dave Helms
    #9 davehelms, Apr 3, 2012
    Hey you... long time!

    Yes, I dont think we can state anything as an absolute in this area, just wishful thinking. That is why I only stated my own personal experiences, which really means nothing in the conversation. IF they fail at high RPM, they will in time fail at any RPM... just as you experienced.
     

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