Jump to content
SAU Community

Recommended Posts

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?

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!

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)?

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...

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.

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...

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?

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


  • Similar Content

  • Latest Posts

    • Hey all,   I’ve got an RB25 with a trigger kit that includes a crank wheel, and I’ve hit a wall trying to sort a timing belt tracking issue. The belt either rides right on the edge of the cam/crank pulleys or walks slightly forward once the engine starts. It tracks okay-ish for a moment, then creeps right to the edge—and honestly, it’s stressing me out.   I’ve spent hours removing and reinstalling the belt, double-checking everything:   Tensioner setup is good, checked multiple times Idler pulley and washers are all in the correct places Followed the RB25 timing procedure step-by-step     The only thing I changed was the rear crank washer—I swapped the OEM one for a Neato version, and it made things worse. The belt now sits even more forward than before. I’m beginning to think the crank trigger wheel itself (from the trigger kit) is the issue—poor design or slightly off dimensions.   What’s strange is that with the previous belt setup, it actually ran fine for a couple of years—around 4,000 to 5,000 miles, even with hard driving and high RPMs. But even then, the belt was always riding right on the edge, and I know that’s not ideal or safe long term.   At this point, I’m debating whether to:   Machine a few mm off the crank trigger wheel to bring it back in line, or Replace it entirely with a better-designed unit     Only thing is, I already have the Cherry Hall sensors, bracket, etc.—I just want to replace the wheel only, not the entire kit. Anyone know a brand or supplier that sells just the crank trigger wheel on its own?   Would really appreciate any feedback—especially from anyone who’s run into this exact issue and found a reliable fix.   Thanks in advance.
    • Hi...a little refresh. Is Nistune gonna be enough to run BoV? Or do i need some proper ECU? 
    • Yep that's pretty much what I want to see. Racecars that look and sound like the Group A but with newer tech underneath to make them faster and safer. I'm sure there's enough VK-to-VN commodore, E30 BMWs and Foxbody mustangs shells around to make up a decent number of cars with hopefully a couple of sierras, rx7 and R31s in there too. 
    • Contact Jessestreeter.com/Skevas Racing/JustJap for a new r34 rb gearbox or go a cd00# conversion. No point playing with unknown condition gearboxes.
    • Such a shame places like Amaroo Park have been redeveloped, smaller tracks always make for good racing. Cheers for sharing @PranK there's some good Lakeside video's too. Its so hard with older the cars as parts are so rare and everything was made for a particular chassis at that point in time. Even the V8 Supercar Blueprint era cars are all different between each chassis within a team as they learnt things and made improvements. The COTF cars between each Chassis builder is different too especially motor/oil systems/intakes. The Group A stuff is worth so much too especially chassis with good history. The only way to do it would be composite panels and similar engine drivelines to the original cars. Ford sierra running Focus RS driveline, Commodore running a short stroke LS/LT or a Falcon with coyote and a H Pattern dog box. Could use a standard ecu across all models with a Torque Map and DBW for parity which is not even used in Supercars currently. Hell a TCM is almost a full chassis car these days and the suspension is not even close to standard style in the front running cars.  
×
×
  • Create New...