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Rocker arm geometry

Discussion in 'S30 (240Z,260Z,280Z) Engine' started by dotMorse, May 16, 2019.

  1. Huw

    Huw
    Z Club Member
    Staff Member

    Hi Tom

    As Jon said new rocker and old cam is fine. If it was me I would change the rockers, springs and lash pads. But you would be best mocking up the rocker to determine what size lash pads first. I’ve use the old ones with feeler gauges to do this.

    Huw
     
  2. dotMorse

    dotMorse
    Z Club Member

  3. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

  4. dotMorse

    dotMorse
    Z Club Member

    Lovely. Would you lube using this as well? Or just use this and not the assembly lube? Or add this to the oil at the first fill and start?
     
  5. dotMorse

    dotMorse
    Z Club Member

    What do you reckon? Do they need replacing? Visible groove as you run your finger nail over.
     

    Attached Files:

  6. dav118118

    dav118118
    Z Club Member

    I would lube up cam lobes and rocker faces to protect from initial start up and use the additive in the oil for running in.

    Luke
     
  7. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    I think I'd replace rockers like that if I could.
    Agree with Like on the lube.
    Always run with zddp.
     
  8. toopy

    toopy
    Z Club Member

  9. dotMorse

    dotMorse
    Z Club Member

  10. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    I believe the ITM ones are fine. Kenjutsu is the 'brand' of the ebay seller, conceptua.
    I've bought brake shoes and thermostat from them and they're OK.
    I doubt they have a unique supply - it wouldn't surprise me if they were ITM too.
    I did ask them who made their brake shoes but they declined to answer.
     
  11. richiep

    richiep
    Z Club Member

    Absolutely get the ITM ones from Rockauto. ITM are a well known, extensively used brand (example - the 87mm pistons in my Z's L28 are ITM), and Rockauto's pricing is simply much better. Kenjutsu/Conceptua are fine, but expensive for comparable parts.
     
    jonbills likes this.
  12. dotMorse

    dotMorse
    Z Club Member

    Just an update. Installed the first set of head shims from Mike @ MJP and it brought the wipe pattern a lot more central, but not quite there. I do now have adjustability on the pivot bolt to give me the cam clearance needed.

    Also have a new set of ITM rocker arms from Rockauto who as always deliver almost too quickly (Turning up on Thursday after ordering last night). I have also got a complete spring set from Zcar as the ITM were out of stock and I would rather keep pressing forward.

    Will update again once all the new hardware is in.

    Tom
     
    jonbills likes this.
  13. dotMorse

    dotMorse
    Z Club Member

    Rocker arms arrived today. They look good. Do you need to do anything to the faces before install apart from lubing. Some people have been saying they resurface them before install but they look fine to me.
     

    Attached Files:

  14. Rob Gaskin

    Rob Gaskin Treasurer in training Staff Member Moderator

    Tom, so do you reckon shims did the trick? If so it must have been running poorly before and the cam timing would have been out by a long way.

    Good job you looked!
     
  15. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    No just install them - resurfacing is for used ones IMO
     
  16. dotMorse

    dotMorse
    Z Club Member

    Yeah my thoughts also. There was a guy who said he had all his ITM rockers refaced from new before install so just made me question it.

    Rob, the shims have certainly helped. I think I need one more set which Huw has kindly sent over (although it's stuck in the snail mail). Hopefully will turn up today and I can rebuild.

    I did drive the car breifly when I bought it and it seemed 'ok'. I always planned a strip and rebuild do asking as it was running well then I wasn't too concerned.
     
    MaximG likes this.
  17. dotMorse

    dotMorse
    Z Club Member

    Evening all. So yet another evening on the car but finally some progress. Installed the 2 sets of head shims and the first 4 rocker arms. The wipe pattern is now within 0.52mm of the center. The valve side reading 0.85mm and the pivot side at 1.37mm which I think is pretty good.

    In other news the previous owner obviously didn't like using a torque wrench as 3 of the threads had helicoils in which tore apart when I tried to torque the bolts. So these where taken out, the threads cleaned and reground and new helicoils dropped in which, luckily,a neighbour who stopped to have a chat happened to have from a Ducati rebuild.

    Not looking forward to what else I will find now but hopefully upwards from here.
     
  18. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    Good news.
    Was that torquing the cam tower bolts? What value did you use? The honsowetz book has wrong values in one place - says 30 ftlb I think when It should be about 12.
     
    MaximG likes this.
  19. dotMorse

    dotMorse
    Z Club Member

    That would explain it. It says 25-33 ft lbs which did seem too tight for aluminium. Stupidly I did'nt question it. 12ft lbs would be a lot nicer. Not great for a book on rebuilding the engine.
     
    Last edited: May 24, 2019
    MaximG likes this.
  20. jonbills

    jonbills
    ZClub Administrator
    Staff Member Moderator

    I fell for it too my cam tower threads are helicoiled as well!
     
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