Jump to content
SAU Community

Did Something Dumb When Torquing Down Rb30 Head

dorifticon

By dorifticon,
in General Maintenance

 Share

Recommended Posts

dorifticon Community Regular

dorifticon

Posted
Posted

Yes, was distracted, missed a key step, hope I haven't junked the motor.

rb30 is an interference motor.

Was torqueing down head, had the no.1 cylinder set to TDC, forgot to clock the cam pin to the top.

Instead of the pin sitting at 12 o'clock, was sitting at roughly 3 oclock.

3 oclock puts the valve on the piston.

was able to rotate the cam backwards to 12 oclock but there didn't seem to be much movement past where it was sitting originally in the clockwise direction.

because the piston was at TDC, the valve wouldn't have pushed it down.

how likely is it that I've bent a valve?

Shoota_77 Veteran

Shoota_77

Posted
Posted

Yeah they don't take much to bend. Put the belt on (timed correctly obviously) and turn the motor over. Check to see if the valve is fully seating once it comes off the cam and is closing (watch the spring to see how smoothly it closes the valve). If it either grabs then releases or just doesn't seat at all them I'mm sorry to say but get that head off again!

dorifticon Community Regular

dorifticon

Posted
  • Author
Posted

Yeah they don't take much to bend. Put the belt on (timed correctly obviously) and turn the motor over. Check to see if the valve is fully seating once it comes off the cam and is closing (watch the spring to see how smoothly it closes the valve). If it either grabs then releases or just doesn't seat at all them I'mm sorry to say but get that head off again!

Is it possible to see whether the valve is seating with the rocker cover off (but the head still bolted down)?

dorifticon Community Regular

dorifticon

Posted
  • Author
Posted

If you have literally just bolted the head down, why not take it back off and look

Well, didn't want to throw away a set of stretch bolts if there was some way of telling if it was ok without removing the head, but it may come to that...

Shoota_77 Veteran

Shoota_77

Posted
Posted

Is it possible to see whether the valve is seating with the rocker cover off (but the head still bolted down)?

Pretty much. You'll be able to see the valves through the ports but mainly you will be able to see the difference in height of the valve tip/spring when the compared to those next to it. If it's stuck open it will be sitting lower than the other valves when they're closed. If it's hard to turn over when the lifter starts to climb the lobe (on the problem cylinder) then the valve could be bent but straight enough to close but then grabbing in the guide when it tries to open.

dorifticon Community Regular

dorifticon

Posted
  • Author
Posted

Depending on what you have available pressurising the cylinder through the spark plug hole will show up a bent valve easily. As would a comp test

yep, going to try to get a hold of a leakdown tester this weekend.

Ordinarily would not care about $46 for a set of bolts, but they won't be delivered by this weekend and I need the car running ASAP, was hoping to get it installed back in the car over the long weekend. If I can get a leakdown test done on Sunday I'll either be able to go ahead with installation, or buy bolts and valves as required on Tuesday...

Thanks for all the responses!

  • 2 weeks later...
dorifticon Community Regular

dorifticon

Posted
  • Author
Posted

UPDATE: as I suspected I bent one of the valves, it's only on 5 now.

There's a reasonably priced reco head on Ebay, but it's for a VL Commodore rb30e, not a skyline.

I heard they had different cams - will this be a problem? Also will it bolt up and run okay with the r31?

Shoota_77 Veteran

Shoota_77

Posted
Posted

Just swap your cams into the new head if you're worried they'll be different (I don't imagine they'll be different enough to be a problem). They're hydraulic lifters so you don't need to worry about clearances or anything, just whack them in and off you go.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • joshuaho96
      Nismo coppermix twinplate clutch

      By joshuaho96 · Posted

      From the pictures I have when doing the job the flywheel is the same diameter, I don't think they're playing weird tricks like putting weights at the outer diameter to increase flywheel inertia or anything like that. The OEM flywheel is definitely heavier, but it's not a huge difference. Quoted weight savings of the clutch is 2 kg so I can't imagine the flywheel being lighter than ~7 kg. Kind of regret not weighing it before the clutch went into the car but as far as driveability goes I have no complaints.
    • joshuaho96
      R32 update from 1990's spec.

      By joshuaho96 · Posted

      HKS trigger kit should be very easy to integrate with a Link. It's a 36-2 crank trigger. Hard part is finding the motivation to take off the timing belt and everything on the front of the engine to install it. You also need to cut out a hole in the oil pump housing so the sensor can read the trigger wheel. Changing out the cam sensor for a 24 tooth setup is probably good enough but as others have mentioned depending on what underlying assumptions are changed it becomes more of a problem. Reading the crank state off of the cam is an abstraction that works in the general case, but if you have an edge case it makes less and less sense. There is a GTX2860 gen 2 that can take a compact 5 bolt housing so it's direct bolt on but I'm not 100% sure of what's involved. Peak compressor efficiency drops off a bit on these turbos vs -5s, 77% vs 73% but you get way, way wider region of operation. The -5s have a really strange surge line in their compressor map that is all over the place. If you think the hot side on the -5s aren't open enough you can try the Tomei T550B turbos which a local tuner seems to be happy with:
    • hfygrte52
      R33 GTR tail light

      By hfygrte52 · Posted

      i need a complete tail light for my R33 GTR if you have please let me know.
    • hfygrte52
      Needs

      By hfygrte52 · Posted

      I need a great maintenance workshop around Idaho, if you know one please let me know..
    • hfygrte52
      Need 1993 GTR

      By hfygrte52 · Posted

      Hello friends, i have a good friend in Canada that looking for a good condition 1993 GTR around him please if one or know someone around you that is willing to let it go please let me know so that i can inform him.....Thanks
×
×
  • Create New...