RB26DETT Valve Clearences

[maverick_au98]

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

Getting head fixed and need to know asap.

Thanks

[wrxhoon]

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]

Thanks. Ive had it all set up properly now, but it looks like the engine has more severe problems than just the valves. Pulling the whole engine out and starting a fresh rebuild.

[maverick_au98]

Thanks. Got it all set up, but it looks like there are other problems with the engine. Pulling it out for a full rebuild now...

[wrxhoon]

Whats the problem with it ? piston let go ?

[maverick_au98]

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 $$$...

[Beer Baron]

sorry to hear about your engine, but I love the sig

very nice.

[wrxhoon]

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]

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]

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]

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]

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]

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?

[Duncan]

bottom end out? test, polish and balance crank and other bits. put a sump extension of some sort in.

[SteveL]

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]

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 .

[Cubes]

If you get the forgy's I would look at getting the skirts coated so you can close down the gap to .020".

[maverick_au98]

If you get the forgy's I would look at getting the skirts coated so you can close down the gap to .020".

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

[maverick_au98]

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]

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.