Jump to content
SAU Community

RB26DETT Valve Clearences

maverick_au98
 Share

Recommended Posts

wrxhoon Grand Master

wrxhoon

Posted
Posted
What are the inlet and exhaust valve clearences for a 95 R33 GTR VSpec?

Getting head fixed and need to know asap.

Thanks

Cold , intake 0.42-0.48 and exhaust 0.35-0.41 mm

i would go on the higher side so you dont burn any valves and put up with the a bit of noise .

maverick_au98 Contributor

maverick_au98

Posted
  • Author
Posted

Idler pully snapped off which changed cam timing to make the pistons and valves all try and occupy the same space at the same time...(Damm... that never works!) Compression not good on all cyl so now im suspecting piston rings or piston problems. All looked good from the top when it was appart. Now all i can see is $$$...

wrxhoon Grand Master

wrxhoon

Posted
Posted
Idler pully snapped off which changed cam timing to make the pistons and valves all try and occupy the same space at the same time...(Damm... that never works!)  Compression not good on all cyl so now im suspecting piston rings or piston problems. All looked good from the top when it was appart. Now all i can see is $$$...

You probably find that you have some bent valves . did you check compression before you stripped the engine ? if yes and you ahve already servied the cil head , check the top of the piston in cil that compression was down for cracks . You will need a big magnifing glass , then check the bore for scoremarks . If there is no marks on the bore the rings will be o.k. and if there is no cracks on the pistons they will be o.k. too .

If the engine is old then have the bottom end done as well .

maverick_au98 Contributor

maverick_au98

Posted
  • Author
Posted
You probably find that you have some bent valves . did you check compression before you stripped the engine ? if yes and you ahve already servied the cil head , check the top of the piston in cil that compression was down for cracks . You will need a big magnifing glass , then check the bore for scoremarks . If there is no marks on the bore the rings will be o.k. and if there is no cracks on the pistons they will be o.k. too .

If the engine is old then have the bottom end done as well .

ALL valves were bent. ZERO compression. Got head fixed and back on (all new valves/ shims/ guides) 130 comp and with oil in cyl, 190 comp. No score marks in bore. So was guessing ringlans, but will check top of pistons.

Going to change them to forgies if their stuffed. Engine only done 60000km and last 10000 on freeway. Never seen any bad smoke besides some black under boost. Really got me stuffed, but i'll know monday when its all apart.

wrxhoon Grand Master

wrxhoon

Posted
Posted

Was there 130 comp on all 6 ? if yes you should do a leakdown test . It maybe your gauge , did you warm the engine to normal operating temp before test ? did you have throtle open fully ? If you put to much oil in the cil its going to increase comp a lot .

maverick_au98 Contributor

maverick_au98

Posted
  • Author
Posted

Good point. You just made think of something. Leakdown test on first go showed 3%. Then the exhaust cam broke (head rebuilder tensioned too much in middle first im guessing) when it was first started. Cam replaced. Idle good. No power. Leakdown test showed 25% on some cyl. I'm going to have to check with the guy who did the leakdown test, but im guessin its the same cyl's that the exhaust cam stoped turning on and its over preasurised the cyl and damaged something.

Sound like a feasable theory?

wrxhoon Grand Master

wrxhoon

Posted
Posted

Are you sure when the can broke it didnt damage the valves ? look at it this way , the exhaust valves are down ( broken cam ) pistons come up the will hit the valves and maybe bent them , just like before . If you have cracked pistons you should be able to see something and you cant have broken rings or ringlands and unmarked bore , surely you will see some scoremarks !!

I would look for another engine builder if i was you as well !

maverick_au98 Contributor

maverick_au98

Posted
  • Author
Posted
Are you sure when the can broke it didnt damage the valves ? look at it this way , the exhaust valves are down ( broken cam ) pistons come up the will hit the valves and maybe bent them , just like before . If you  have cracked pistons you should be able to see something and you cant have broken rings or ringlands and unmarked bore , surely you will see some scoremarks !!

I would look for another engine builder if i was you as well !

Valve's are all ok. From a visual inspection of the parts today, could not see what was causing low compression. The cyl's that the cam stoped turning on, actually had the higher compression. I was told the pistons in these engines run such fine tolerances that a hairline crack could be quite possible.

So am getting forgies as their not much more than standards. Getting 20 tho overbore, fully ballanced bottom end, done by a mob who build race and drag engines. This will help with engine response rev speed.

Anything else i should do to the bottom end while its in bits?

SteveL Mentor

SteveL

Posted
Posted
Valve's are all ok. From a visual inspection of the parts today, could not see what was causing low compression.

Visual inspection isn't really good enough.....doesn't take much of a bend to cause poor seating. Valve head run-out should be checked, or at least the quality of the valve/valve seat seal should be checked using bearing blue (or similar).

wrxhoon Grand Master

wrxhoon

Posted
Posted
Valve's are all ok. From a visual inspection of the parts today, could not see what was causing low compression. The cyl's that the cam stoped turning on, actually had the higher compression. I was told the pistons in these engines run such fine tolerances that a hairline crack could be quite possible.  

So am getting forgies as their not much more than standards. Getting 20 tho overbore, fully ballanced bottom end, done by a mob who build race and drag engines. This will help with engine response rev speed.

Anything else i should do to the bottom end while its in bits?

Sure a hairline crack will lose you compression regardless what tolerances you have but you have low comp on all 6 . I would be checking the cyl head before puting it back together if i was you .

Did you have 100% compression before this ?

Stock pistons you have 1.5 thou clearence , forgies it depends on the brand but around 4 thou .

The cam would have stopped on all the rear cylinders , only the front part would be turning .

maverick_au98 Contributor

maverick_au98

Posted
  • Author
Posted
Sure a hairline crack will lose you compression regardless what tolerances you have but you have low comp on all 6  . I would be checking the cyl head before puting it back together if i was you .

Did you have 100% compression before this ?

Stock pistons you have 1.5 thou clearence , forgies it depends on the brand but around 4 thou .  

The cam would have stopped on all the rear cylinders , only the front part would be turning .

Have had the head checked out again by the guy who rebuilt it. He has fixed the loose valve settings with the shims. All the valves were fine. Looks like the tap to the tops of the pistons broke the seal the rings had. Top ring had been hammered from extra boost from previous owner. Second ring was a bit wide in the gap. This was causing the crank case to get preasurised from blow by. Now getting oversized forgies 20thou and hone. Fully balancing bottom end.

Cubes Grand Master

Cubes

Posted
Posted
What do the skirts need to be coated with? Is it like a chrome molly or similar?

I'm unsure exactly what the coating is.

When ordering the pistons you request if you want the skirts coated in order to reduce friction and clearance.

i.e Arias.

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

    • Duncan
      V37 Suspension change

      By Duncan · Posted

      And finally, the front lower mount. It was doubly weird. Firstly, the lower mount is held in with a bracket that has 3 bolts (it also acts as the steering lock stop), and then a nut on the shock lower mount itself. So, remove the 3x 14mm head bolts , then the 17mm nut that holds the shock in. From there, you can't actually remove the shock from the lower mount bolt (took me a while to work that out....) Sadly I don't have a pic of the other side, but the swaybar mounts to the same bolt that holds the shock in. You need to push that swaybar mount/bolt back so the shock can be pulled out past the lower control arm.  In this pic you can see the bolt partly pushed back, but it had to go further than that to release the shock. Once the shock is out, putting the new one in is "reverse of disassembly". Put the top of the shock through at least one hole and put a nut on loosely to hold it in place. Put the lower end in place and push the swaybar mount / shock bolt back in place, then loosely attach the other 2 top nuts. Bolt the bracket back in place with the 14mm head bolts and finally put the nut onto the lower bolt. Done....you have new suspension on your v37!
    • Duncan
      V37 Suspension change

      By Duncan · Posted

      And now to the front.  No pics of the 3 nuts holding the front struts on, they are easy to spot. Undo 2 and leave the closest one on loosely. Underneath we have to deal with the wiring again, but this time its worse because the plug is behind the guard liner. You'll have to decide how much of the guard liner to remove, I undid the lower liner's top, inside and lower clips, but didn't pull it full off the guard. Same issue undoing the plug as at the rear, you need to firmly push the release clip from below while equally firmly gripping the plug body and pulling it out of  the socket. I used my fancy electrical disconnect pliers to get in there There is also one clip for the wiring, unlike at the rear I could not get behind it so just had to lever it up and out.....not in great condition to re-use in future.
    • Duncan
      V37 Suspension change

      By Duncan · Posted

      Onto the rear lower shock mount. It's worth starting with a decent degrease to remove 10+ years of road grime, and perhaps also spray a penetrating oil on the shock lower nut. Don't forget to include the shock wiring and plug in the clean.... Deal with the wiring first; you need to release 2 clips where the wiring goes into the bracket (use long nose pliers behind the bracket to compress the clip so you can reuse it), and the rubber mount slides out, then release the plug.  I found it very hard to unplug, from underneath you can compress the tab with a screwdriver or similar, and gently but firmly pull the plug out of the socket (regular pliers may help but don't put too much pressure on the plastic. The lower mount is straightforward, 17mm nut and you can pull the shock out. As I wasn't putting a standard shock back in, I gave the car side wiring socket a generous gob of dialectric grease to keep crap out in the future. Putting the new shock in is straightforward, feed it into at least 1 of the bolt holes at the top and reach around to put a nut on it to hold it up. Then put on the other 2 top nuts loosely and put the shock onto the lower mounting bolt (you may need to lift the hub a little if the new shock is shorter). Tighten the lower nut and 3 upper nuts and you are done. In my case the BC Racing shocks came assembled for the fronts, but the rears needed to re-use the factory strut tops. For that you need spring compressors to take the pressure off the top nut (they are compressed enough when the spring can move between the top and bottom spring seats. Then a 17mm ring spanner to undo the nut while using an 8mm open spanner to stop the shaft turning (or, if you are really lucky you might get it off with a rattle gun).
    • Duncan
      V37 Suspension change

      By Duncan · Posted

      You will now be able to lift the parcel shelf trim enough to get to the shock cover bolts; if you need to full remove the parcel shelf trim for some reason you also remove the escutcheons around the rear seat release and you will have to unplug the high stop light wiring from the boot. Next up is removal of the bracket; 6 nuts and a bolt Good news, you've finally got to the strut top! Remove the dust cover and the 3 shock mount nuts (perhaps leave 1 on lightly for now....) Same on the other side, but easier now you've done it all before
    • Duncan
      V37 Suspension change

      By Duncan · Posted

      OK, so a bunch of trim needs to come off to get to the rear shock top mounts. Once the seat is out of the way, the plastic trim needs to come off. Remove 2 clips at the top then slide the trim towards the centre of the car to clear the lower clip Next you need to be able to lift the parcel shelf, which means you need to remove the mid dark trim around the door, and then the upper light trim above the parcel shelf. The mid trim has a clip in the middle to remove first, then lift the lowest trim off the top of the mid trim (unclips). At the top there is a hidden clip on the inner side to release first by pulling inwards, then the main clip releases by pulling the top towards the front of the car. The door seal comes off with the trim, just put them aside. The the lighter upper trim, this is easy to break to top clips so take it carefully. There is a hidden clip towards the bottom and another in the middle to release first by pulling inwards. Once they are out, there are 3 clips along the rear windscreen side of the panel that are hard to get under. This is what the rear of the panel looks like to assist:
×
×
  • Create New...