Register now to get rid of these ads!

advise needed polylocks

Discussion in 'The Hokey Ass Message Board' started by Mr Haney, Dec 30, 2008.

  1. Mr Haney
    Joined: Jul 17, 2008
    Posts: 1,001

    Mr Haney
    Member

    runnin a rather big crane SOLID camshaft.....constantly running valves.
    They will not stay adjusted, loosen up after a few runs on motor. Am I missing something here. I do have roller tip rockers with polylocks but they just wont stay in adjustment. Any suggestions ? ? The studs are not pulling out changed them to screw in with noiling through pushrods. 389 pontiac 63 heads. thanks in advance for your input...Mr Haney
     
  2. Racewriter
    Joined: Nov 14, 2008
    Posts: 780

    Racewriter
    Member

    I had this problem on a racing SBC one time. I'm going to assume that you're getting the poly locks good and tight, so the elementary stuff is out of the way.

    In my case, I was running a radical cam and a set of Harland Sharp rockers. When mine kept coming out of adjustment, the people at Harland Sharp told me that the studs themselves might be flexing and allowing the locks to loosen. I installed a stud girdle, and the problem went away.
     
  3. I would call Crane up & ask them
    or use Lock tite on the Poly-locks
    just my 3 cents
     
  4. take a look at the ends of your rocker arm studs , if they are not perfectly flat and square the center set screw doesn't get the proper grip on them. i use to machine them flat on the sbc's i raced with and it seamed to make a difference
     

  5. ProEnfo
    Joined: Sep 28, 2005
    Posts: 1,498

    ProEnfo
    Member
    from Motown

    Great tip, thanks...........

    cc
     
  6. GreggAz
    Joined: Apr 3, 2001
    Posts: 929

    GreggAz
    Member

    I would 2nd the stud girdle idea, had a similar issue on a boat motor recently.
     
  7. bigolds
    Joined: Oct 27, 2006
    Posts: 883

    bigolds
    Member

    A stud girdle on a huge cam is a smart move. Flex will cause the poly's to loosen!!!
     
  8. Mr Haney
    Joined: Jul 17, 2008
    Posts: 1,001

    Mr Haney
    Member

    thanks for the input. my factory pontiac heaqds seem to have a stud girdle kinda cast into heads from factory, pretty cool inovation from pontiac. The studs from what i remember were machined flat. Will check out that venue closer. Never heard of locktight method but phone call to crane dont hurt. Must add that keeping the rpm's down under 6K is a bit of a challenge .....gotta work on that.....got stock 63 rods......ran out of money.

    thanks......Mr Haney
     
  9. ResedaCoupe
    Joined: Nov 8, 2004
    Posts: 109

    ResedaCoupe
    Member

    Hello,
    Are you tightening both the lock and nut together for the last 1/8-1/4 turn? On most engines I have worked on this is the only way I have been able to keep them from loosening up. I have been informed that there is no way just using the small lock will hold on some engines. This will suck on a solid cam. Another tip I got was to set your hot lash on one cylinder and re-measure when the engine is cold. Now you can set the rest cold.
    Hope it helps
     
  10. Mr Haney
    Joined: Jul 17, 2008
    Posts: 1,001

    Mr Haney
    Member

    NO....is my answer to your question. I was simply bringing adjustment up to spec, then locking the allen head set screw down. Hey, that makes sense to me, never thought . I like the cold adjust method you mentioned but is that kosher ? ? My studs were faced off at machine shop so they dead flat [ earlier suggestion ] thanks for the tips....well understood
    Mr Haney
     
  11. ResedaCoupe
    Joined: Nov 8, 2004
    Posts: 109

    ResedaCoupe
    Member

    Try locking both together for an 1/8th turn, see if that helps.
    If it is a different cylinder all the time it should fix it. If its the same or only a couple make sure you don't have a lobe going away.
    Yes the cold lash bit also works, I stay away from using a number because different setups change differently. I record this setting (cold lash) on tear down of engines I work on so it could be re-set for initial start up.
    It works well for a couple of 650hp bb chevys with a solid rollers I work on. Try it, you may be suprised how little it moves.
     
  12. Mr Haney
    Joined: Jul 17, 2008
    Posts: 1,001

    Mr Haney
    Member

    NO not the L-word they do vary fortunatly....Great advise will give it a try. When i say this thing wont stay adjusted, I am talking every 150 miles of moderate abuse , they will require adjustment. Funny that diesel engines with solid cams [ cat] ncan go 60K before adjustment required !

    Best Mr Haney
     
  13. OoltewahSpeedShop
    Joined: Oct 18, 2007
    Posts: 3,103

    OoltewahSpeedShop
    Member

    I don't know if you can get a stud girdle for a Pontiac, but if so... This will solve your problem. We have run them on everyting from full race engines to hot street stuff. The girdle will stop all that movement that is causing your poly locks to come loose. The poly lock is only as good as the set screw. When the rocker stud deflects, the set screw looses its grip on top of the stud. The girdle not only stops the deflection, but has a firm grip on the outside of the poly lock to keep it from backing off. You will have to buy a poly lock made for a stud girdle, they are taller to allow them to come up through the girdle. The only draw back to all of this is that your valve covers will not be tall enough to clear the stud girdle and tall poly locks.

    Hope this helps.

    Later,
    Kevin
    Ooltewah Speed Shop
     
  14. Mr Haney
    Joined: Jul 17, 2008
    Posts: 1,001

    Mr Haney
    Member

    Kevin , My friend at Obsolete Engineering can make me up a VC spacer no problem. I hate having to wear a girdle......whats next a bra ? ? Just kiddin ! tech info understood and appreciated.

    Pitts64.... gotta work on mrs douglas house before buying any more speed equipment ......Hot Dammn ! Good though !
     

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.