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Top end knocking

Discussion in 'S30 (240Z,260Z,280Z) Engine' started by Peato40, Apr 26, 2018.

  1. jonbills

    jonbills
    Z Club Committee
    Committee Member

    And what valve clearances have you set, and where did you measure them? I only ask because I used to measure them between cam and rocker, which makes bigger and noisier!
     
  2. Peato40

    Peato40
    Z Club Member

    I haven't put it back together yet, in case somebody recommended I check something whilst it's open but in any case I'll put the sump back and fresh oil by the weekend and then take another video.
     
  3. Peato40

    Peato40
    Z Club Member

    I set the intake to 0.2mm and exhaust to 0.25mm and yes I did measure between the heal of the cam lobe and the arch of the rocker arm ...... is that wrong?
     
  4. jonbills

    jonbills
    Z Club Committee
    Committee Member

    Yeah I now reckon you should measure between lash pad and rocker. For 1mm movement at the cam there’s 1.5 at the valve, so I reckon that means your 0.2 and 0.25 clearances become 0.3 and 0.375 which is definitely noisier.
     
  5. Peato40

    Peato40
    Z Club Member

    Okay, so I'll tighten things up also before I test it again. Is there anything I should check on the bottom end before I put the sump back on do you think?
    I hope it is just a valve train clearance issue.
     
  6. jonbills

    jonbills
    Z Club Committee
    Committee Member

    I’d be inclined to take a couple of rod and main caps off to check the bearings look ok while you’re there, and then it can’t hurt to check the torque on all of them when you put them back.
     
  7. Peato40

    Peato40
    Z Club Member

    I took a look last night and didn't find anything horrifying, anybody else have any concerns?

    20180515_181512.jpg 20180515_181425.jpg 20180515_175956.jpg 20180515_175941.jpg 20180515_175913.jpg 20180515_174123.jpg 20180515_173010.jpg 20180515_172810.jpg

    I'll get the sump back on and charge it with fresh oil by the weekend, so that I can start it and take a new video.

    Phil
     
  8. jonbills

    jonbills
    Z Club Committee
    Committee Member

    Pics 3 & 6 aren’t so pretty but I don’t think they show anything serious. Anyone else?
     
  9. franky

    franky
    Z Club Member

    I'd say they don't look like brand new bearings?

    Can you feel the marks shown in the pics with your nail? It looks like its picked up a little? Looking at the uneven coating-surface wear? What do you think John?
     
  10. jonbills

    jonbills
    Z Club Committee
    Committee Member

    I think a few of them have the shiny look mine have after a season of use, they all show a little dirt embedded (which is hard to avoid completely) but pic 6 does look like there’s material missing on that left edge - but could be just the pic.
     
  11. Peato40

    Peato40
    Z Club Member

    The shells are all smooth, no signs of gauling or missing material. After re-assembly I tried to see if there was any movement indicating excessive wear but I could only detect slight lateral movement on the shaft.
    Do you think it might be a safe option for me to get a new set before running again?
     
  12. Albrecht

    Albrecht Active Forum User

    Sorry to be a voice of doom here, but I've stripped engines with tens of thousands of miles on them with bearings looking better than those. They don't look good at all to my eye.

    What was the process with sizing/selecting the bearings? Was the crank accurately measured and bearing grades picked to suit?
     
  13. Peato40

    Peato40
    Z Club Member

    Okay then I'll get some new bearings on order. I actually purchased my car and engine as a partial restoration and the bottom end already built with a freshly honed block and painted block. The head had been freshly skimmed too but I soon realized that it needed new guides and then also I discovered that it was skimmed so much that it would then need too many cam tower shims to get the cam and timing gear in a comfortable position, so this is were I concentrated my time and money. So I actually don't know what was the selection process and now have doubts that new bearings were installed at all.

    So I think the next step for me is to mic up the crank journals and see what I have to work with and hopefully it will be a case of installing a new set of shells and not a crank re-grind.
     
  14. Rob Gaskin

    Rob Gaskin Membership Secretary Staff Member Committee Member

    Phil, these are purely my views based on the video and pictures.

    The noise MIGHT not be excessive - if I start my blue car in my garage it's noisy when cold.

    The oil being discoloured may just be old mixing with whats left when it's drained.

    Shells, not the best however the crank journals look ridged and give unusual reflections as if they are not smooth. Is it just me that thinks this?
     
  15. franky

    franky
    Z Club Member

    they look the same as the last engine where the bottom end picked up(s50 range), its the fact you can see lines in them and some evidence of uneven wear.

    can you humor me, on one of the shells you've not removed, can you torque the bolt to factory specs? To see if you get any turn on before its set?
     
  16. Peato40

    Peato40
    Z Club Member

    Thanks Rob, my car doesn't get any quieter when warm unfortunately.
    I'll take a closer look at those journals but I seem to recall them being smooth, although I have to admit they don't look so great in the photos.
     
  17. Peato40

    Peato40
    Z Club Member

    Hi Franky, I refitted those caps after removal last night and torqued to 35 ftld ..... but I'm not sure what you mean by "if I get any turn on before it's set"?
     
  18. racer

    racer
    Z Club Member


    I'd be concerned that your head has been skimmed that much, and you don't know what your clearances are?
    Compression check time I think.
     
  19. franky

    franky
    Z Club Member

    I meant before you remove them all, check that they're actually torqued correct.
     
  20. Peato40

    Peato40
    Z Club Member

    Hello Racer, I abandoned the original head and then got a much fresher one. This then went to Automotive services for a freshen up with new valves and guides fitted. I installed a fast road cam and Schneider springs and lash pads to suit the cam. I think the head is okay but we'll see when I get it running properly.
     

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