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

    • PranK
      R32 GTR EV? The leaf of the Godzilla's!

      By PranK · Posted

      https://www.dezeen.com/2025/01/06/nissan-electric-r32-skyline-gt-r-godzilla-sports-car/   I reckon this is pretty cool. Lots of other Resto mods have turned to ev power.
    • DraftySquash
      RB25DET Engine Oil Dipstick Length

      By DraftySquash · Posted

      hahaha @joshuaho96 the most action it gets is when I have to drive from West to SE VIC to meet the fam. Even then, it;s on highway cruising speeds
    • thatjawncrazy
      Mistakes were made, my R34 Story

      By thatjawncrazy · Posted

      don't know anyone in this thread, but i just found it, read the entire thing in a few hours, realized greg is still posting progress, and just have to say, this is awesome. it looks awesome. 100% right about the Uras kit making it a pain to get on hoists...have the same kit on my 34 and it takes six 2x4s and race ramps to do it without taking parts off. this reminds me exactly of this thread. https://grassrootsmotorsports.com/forum/build-projects-and-project-cars/r63-amg-the-unicorn-of-my-destruction/110824/page8/
    • GTSBoy
      Fixing exhaust position?

      By GTSBoy · Posted

      The only way to make that better is to weld on some bozozoku tips up past window height and roll with the cool kids.
    • Kinkstaah
      Fixing exhaust position?

      By Kinkstaah · Posted

      I'd want an even MORE side on view. More or less you want to make sure the outlet is actually square with the outermost part of the bumper. Or you end up getting soot all over your bumper from your hektik exhaust. In any case, it looks pretty close. I think the way to fix this is probably more of an overhaul at an exhaust specialty shop if you want tips that are rounded off or sit nicely with the bumper but have proper clearance and don't move - Probably more of a redesign than a quick fix. I've pencilled in my own exhaust with its own various problems, pinholes, PITA fitment, and other issues and can see myself going to a shop and saying "JUST DO THIS BUT BETTER?"  Which is gonna work better than any more small fixes. I'm gonna chime in here officially with "from an outsider perspective this exhaust looks fine so this is self OCD probably" (which I also suffer from)
×
×
  • Create New...