News

I thought 308 cams were "brittle?"

Discussion in 'Technical Q&A' started by Meister, Dec 21, 2005.

  1. Meister

    Meister F1 Veteran
    Silver Subscribed

    Apr 27, 2001
    5,383
    Duluth, MN
    Full Name:
    The Meister
  2. To remove this ad click here.

  3. Birdman

    Birdman F1 Veteran

    Jun 20, 2003
    6,687
    North shore, MA
    Full Name:
    THE Birdman
    I'm guessing those cams aren't straight anymore!
     
  4. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
    NWA
    Full Name:
    Paul
    Not only that, but they talk about spinning the engine over, but it has no belts. I would just assume out of hand it has a lot of bent valves.
     
  5. Meister

    Meister F1 Veteran
    Silver Subscribed

    Apr 27, 2001
    5,383
    Duluth, MN
    Full Name:
    The Meister
    #4 Meister, Dec 21, 2005
    Last edited by a moderator: Sep 7, 2017
  6. mk e

    mk e F1 World Champ

    Oct 31, 2003
    11,829
    The twilight zone
    Full Name:
    The Butcher
    I can't imagine damaging a cam like that...that's a big piece of steel. I think you'd really have to put some effort into bending one.

    The problem with the matchbook under a cam bearing cap in cranking the the cap or stripping the bolt hole, but cracking the cap is the most likely outcome.
     
  7. To remove this ad click here.

  8. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    7,000
    Groton, MA
    Full Name:
    Verell Boaen
    While I don't generally recommend using paper under the cam caps, breaking the cam is NOT one of the reasons for not doing it. Damaging the cam caps is the primary reason.

    I don't know where you've been running into that statement. I know of no way that paper temporarily under the cam cap could damage a cam.

    What you may be confusing is that around '01 or '02, a FerrarList (posslbly it was Fchat) owner reported a cam breaking. He started removing the caps 1 by 1 & about the time he got 3 or 4 of them off, the cam broke in half. A couple of the responses reported similar occurrances.

    My memory is that it was a Flist post.
    I just tried searching the Fchat archives, but couldn't come up with the post.

    I suspect that valve spring pressure acting near the unsupported end of the cam provided the necessary leverage to snap the cam.

    It's possible that this was a flawed cam, but since that report, I've been recommending uniformly backing off the cam cap nuts a turn or so at a time to keep the full length of the cam supported.
     
  9. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,522
    San Carlos, CA
    Full Name:
    Mitchell Le
    That is about $4000 for an unknown block and heads. It may be a tad expensive. Separately, I would guess $1000 for a block with liners, $1000 for the heads, and $1000 for the crankshaft with the cams.
     
  10. Steve Magnusson

    Steve Magnusson F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    19,912
    Texas
    Full Name:
    Steve Magnusson
    I'd say a little too high also (but then I'm not needing one NOW ;)). It's not complete enough IMO to really be called a "long-block" (since it's missing the cam driving stuff).
     
  11. Martin308GTB

    Martin308GTB F1 Rookie

    Jan 22, 2003
    4,125
    Black Forest Germany
    Full Name:
    Martin N.
    I think the camshafts are sturdy enough being not damaged by holding them this way. Even more because they are fixed near the bearings. So there's little bending leverage.

    But while looking at this picture it somehow comes to my mind, that someone who performs something like that might possibly have lifted out the engine with the help of an engine crane connected with the camshafts. Who knows.

    Best Regards from Germany

    Martin
     
  12. To remove this ad click here.

  13. jselevan

    jselevan Formula 3

    Nov 2, 2003
    1,858
    I have used standard 20 weight paper, or a playing card, but a match book cover is too thick. As mentioned below, the danger is to the cam cap, not the cam, and standard paper under two or three caps will not damage the cap, but will provide sufficient friction to allow tightening of the cam bolt.

    Jim S.
     
  14. Artvonne

    Artvonne F1 Veteran

    Oct 29, 2004
    5,379
    NWA
    Full Name:
    Paul
    Having watched parts selling on Ebay, the last crank sold for less than $200. A set of heads have never hit a $1000 that I can recall. This engine is missing the cam covers, and also the timing cover, both of which are machined and align bored to the castling, so without them what do you really have? The last block I seen sell went for about $800. The last cams I seen sold for a few hundred. Those were injected cams.

    As stated, I dont think tieing it down like that will break a cam, but I would guess it has at least a few bent valves seeing the belts are off and they talked about spinning it over.

    I cant honestly see why anyone has to keep the cams from moving with anything, matchbook included. When the engine is at TDC on #1, The aft cams are between lobes, and almost impossible to move without a wrench. one of the forward bank cams is about the same way, and I cant recall which, but the other forward cam wants to "flip" on you. But its not a problem. Its not a problem because the forward bank has ALL of its pistons halfway down the cylinders. Nothing can touch. I just twist it back by hand, and unless you bump it, it will stay put. If you are really trying to get the cams spot on, and especially with a degree wheel, the locked cams with a matchbook would just mess you up, IMO. I have P6 cams, so if I cant hit anything, no one should have much trouble with stock ones. One caveat with mine is that it would be possible for the valves to hit each other, but the cams would have to turn to exact positions, and its not real probable. I do not know if it would be at all possible with stock cams.
     

Share This Page