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
  On 10/03/2016 at 12:27 AM, Shoota_77 said:

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
  On 10/03/2016 at 1:45 AM, 89CAL said:

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
  On 10/03/2016 at 1:10 AM, dorifticon said:

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
  On 10/03/2016 at 6:30 AM, Ben C34 said:

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

    • MBS206
      The Cool Tools Thread

      By MBS206 路 Posted

      Don't use "gasless MIG" (FCAW) you want to use proper MIG. FCAW burns a few hundred degrees hotter than MIG will for mild steel. It is a true ball ache for sheet metal. New MIG / TIG machines even have features like "Spot Weld" as well as "Automatic" settings. Plenty of people say for DIY home hobby, the auto machines are pretty good for 95% of welding. I personally, I'm a sucker for punishment and wanting to dial it in, and be able to adjust the machine. Mainly because I used to MIG weld for a living, and being able to tweak and tune things ever so slightly was my preference. Hence when I bought my ACDC TIG, it has all the adjustments for everything and no "easy" mode. Ha ha I have stick, MIG, "gaslessMIG" and ACDC TIG at home. Out of them, if you're doing mild steel sheet metal repair, and want to do mild steel exhausts, go MIG. If you're thinking you'll want to get into doing some aluminium stuff, or stainless steel, get an ACDC TIG with HF start. If you can, get one with a foot pedal too. My MIG machine is a UniMIG, and my Stick/TIG is CigWeld. If I were buying another machine, I'd buy another CIGWeld. Lots of people having issues with UniMIG, and them not wanting to cover warranty. Everything has to go back to UNIMig themselves. CIGWeld, I've had to use their warranty on my machine for a gas leak, they have repair centres everywhere, (contracted authorised repair centres). First repair place I used were hopeless, but the second place were amazing. Warranty process itself super easy, and second repair place was telling me CigWeld actually cover in their warranty, upto an hour of techs time to help you with your machine, and going through the settings and helping teach you the machine. UniMIG keep trying to get out of replacing motherboards on 12 month old machines.   TLDR, mild steel sheet welding, buy a MIG. my vote is CigWeld for brand.
    • MBS206
      RB25DET Solid lifter conversion

      By MBS206 路 Posted

      I guess that's what happens when someone can't convert metric to freedom units to machine something. 馃槢
    • MrStabby
      The Cool Tools Thread

      By MrStabby 路 Posted

      I've watched some vids and the technique seems to be to butt the sheets up to one another and use MIG to spot weld and slowly fill in the spots until its eventually all sealed. No runs as you would normally do, as there's too much heat generated that way. Yeah my stick welds are terrible these days because its been so long since i've done any of it. I expect to be spending many hours practicing
    • joshuaho96
      RB25DET Solid lifter conversion

      By joshuaho96 路 Posted

      I have personally seen a Tomei USA RB26 cam that didn't even fit the head. Kind of nuts to me that it was even possible for that to happen but such is life.  There's two UP Garages in the US. One is a US branch of the Japanese company which sells things they brought over at tremendous markup. The other is University Place Garage/Fairlady Motors which is a shop best known for putting VCAM in RBs and trying to convince people to stop putting in 800hp of turbo on a 2.5L motor.
    • GTSBoy
      The Cool Tools Thread

      By GTSBoy 路 Posted

      Gasless MIG is not exactly suited to what I would call "delicate" or "attractive" welding. So I would rule it out for sheet metal rust repair type stuff, unless you're only doing it in hidden places. I'm thinking about getting myself a gasless MIG for "hack together" type work. Noting that my welding experience is very very low, and quite a long time ago. So I'm also looking for "simple", but I'm not expecting "excellent". I'm not even sure that proper MIG is the best for sheet metal work. I get the feeling that the degree of control and the minimisation of heat input that you get from TIG is probably what you really want. And then you have to get good at doing it before the welds won't look like a monkey flinging a handful of shit anyway. You're probably SOL for an easy and cheap way to get from where you are to where you want to be. Much like myself.
脳
脳
  • Create New...