Solving zero valve clearance throught other ways.

Hey guys need some brainstorming.
While assembling back the valvetrain, we came to realise we have zero valve clearance. This is because we didnt take into considereation of the shims when cutting the valve seats.

Now the problem is how can we solve the problem other than the proper way of shiming it.
Is there a way we can grind the shims and "rocker arm guide" shims? Or is there other ways u guys have considered such as grinding of the valve stem? I'm sure some of u have managed to grind something in the valvetrain to correct the clearance problem. So any suggestions? Cant seem to find ideas in the search section.

I know this might sound like the short cut way but i'm staying in the middle of no where in Kuala Lumpur, Malaysia and one of the very few running GTi-Rs around and i need the car fast.

Other than that as a worst case scenario who would be the best people to order shims from? I heard there is some company call DP motorsports or something like that where u can order it. Any contacts to it and rough price figures?
If hope i can get away to sourcing shims and hope someone can help out to sort the 0 clearance problem.
Btw would adding a higher lift/ profile cams might solve or aggrevate the problem?
Thanks in advance
 
I

Innovate Performance

Guest
You can get the shims reground to the correct size but you will need to work out how much you need to take off. The best way would be to get 1 ground down more than you need so that you know you will have clearance and then work out all the others 1 by 1.
Then order 1 new shim to replace you one that is way to big, (IE the 1st 1 you had ground down to Far)

Then you should be all ok.

Put in higher lift cams will help but you may still be left with no clearance and you will still have to do the shims any way.
 

zia

Active Member
Hey guys need some brainstorming.
While assembling back the valvetrain, we came to realise we have zero valve clearance. This is because we didnt take into considereation of the shims when cutting the valve seats.
how does cutting new seat change the clearance between cam and and rocker or rocker and shim. the valve will not change it,s length just because you,ve removed a few thou from seat or cut new seat?
Put in higher lift cams will help
don,t think this will help at all the measurement are taken on base, the base is always same it the flank of the cam that changes clearances. best way would be to remove the the shims measure all of them and then try working out what thickness you need or which can if possible need grinding, (again not recommended)

zia
 

Fast Guy

Moderators
Staff member
zia said:
Hey guys need some brainstorming.
While assembling back the valvetrain, we came to realise we have zero valve clearance. This is because we didnt take into considereation of the shims when cutting the valve seats.
how does cutting new seat change the clearance between cam and and rocker or rocker and shim. the valve will not change it,s length just because you,ve removed a few thou from seat or cut new seat?


zia
If you cut the seat, I'm assuming the valve will in effect be sitting higher in the head as material has been removed so letting the valve sit closer to the cam and so the clearance closes up.

You could shorten the valve stem, but I don't know how this will affect the valve collets/shims etc from fitting normally.
 
J

jasegould

Guest
IMO the only way to do it is to fit the correct sized shims, try swopping the shims around til you can get clearances then get them machined down at an engineering shop
Jay
 
I

Innovate Performance

Guest
don,t think this will help at all the measurement are taken on base, the base is always same it the flank of the cam that changes clearances. best way would be to remove the the shims measure all of them and then try working out what thickness you need or which can if possible need grinding, (again not recommended)

zia
They also machine away the base of the cam so that the tappet clearances need to be adjusted to suit you will generally always need to close up the tappet gaps (bigger tappets) once you have fitted higher lift cams this gives you more lift to.
It is all to do with the centre line of the cams in the carriers.

Hope this makes some sense to some of you. :)
 
So i should cosider getting a sample high lift cam to see if that solves the problem or it does not help?
I'm also considering grinding the valve stem as the last resort.
Another question it might sound silly but how do u grind the shims with "grooves"?

And also i have a spare cylinder head and NO, none of the shims correct the zero clearance.
:? :(
 

zia

Active Member
They also machine away the base of the cam so that the tappet clearances need to be adjusted to suit you will generally always need to close up the tappet gaps (bigger tappets) once you have fitted higher lift cams this gives you more lift to.
It is all to do with the centre line of the cams in the carriers.
the base remains the same no matter what lift/duration and grinding the base without knowledge would lead to bigger cockup!!! any way i wouldn,t pay money for high lift only to grind the cam and invalidate the warranty.
If you cut the seat, I'm assuming the valve will in effect be sitting higher in the head as material has been removed so letting the valve sit closer to the cam and so the clearance closes up.
grinding new seat doesn,t involving taking huge metal out, if you do you,ve gone to far into the throat and have pretty much messd up all the flow that you expected from new seats!!!, sure you need to reshim but going from .10mm to .00mm is far too much, and guessing this for all the valve clearances not just one? i guess am talking loads of b*llo*k so will shut up :wink:

zia
 
A

ard1ey

Guest
If you have a spare cylinder head why not build that one up and see if it helps your problem, i.e. standard shims would sort out the valve clearances?
Grinding the camshaft or the valve stem is just a bodge :( - don't do it.
 

geetee

Active Member
KL Malaysia....

Nissan spares nil
skilled engineering shops 10

Get the shims ground to suit, it's only a case of getting a few thou ground off, it'll be fine. Best to get the shims ground, at the end of the day you won't make it any worse, the shims are easily removed and replaced.

AFAIK shims aren't case hardened, they're hard throughout so you can grind them to a wafer.

Cheers
GeeTee 8)
 
U're from Malaysia by chance?
Yeah i would prefer to grind of the shims but the thing is HOW do u grind of the shim with grooves (known as "rocker arm guide" shim in the manual)?
What sort of machine u recommend to get the job done?
Pardon me as i'm not mechanically sound. Just giving suggestions to my mechanic friend who's building it.

The previous cylinder head is warped which is why i replaced it.
Just feel lost after the amount of cylinder head work such as porting, polishing, swirls and blah blah done to it only to be stopped by some 16 shims.

Oh btw are the shims used on the GTi-R the same as the GTR RB26DETT?
 
I

Innovate Performance

Guest
zia said:
They also machine away the base of the cam so that the tappet clearances need to be adjusted to suit you will generally always need to close up the tappet gaps (bigger tappets) once you have fitted higher lift cams this gives you more lift to.
It is all to do with the centre line of the cams in the carriers.
the base remains the same no matter what lift/duration and grinding the base without knowledge would lead to bigger cockup!!! any way i wouldn,t pay money for high lift only to grind the cam and invalidate the warranty.
If you cut the seat, I'm assuming the valve will in effect be sitting higher in the head as material has been removed so letting the valve sit closer to the cam and so the clearance closes up.
grinding new seat doesn,t involving taking huge metal out, if you do you,ve gone to far into the throat and have pretty much messd up all the flow that you expected from new seats!!!, sure you need to reshim but going from .10mm to .00mm is far too much, and guessing this for all the valve clearances not just one? i guess am talking loads of b*llo*k so will shut up :wink:

zia
The new cams are machined from a blank so they can make the the cam profile to what ever they want with in the given allowance of the cam blank. The base of the cam can be different to a standard cam as for this reason.


He has had the valve seats recut which involves taking more metal away. even when you lap valves in you can close up the gaps, You have to remember that we are talking about a gap the size of a couple of fag papers thick.
 
I

Innovate Performance

Guest
BabyGodzillaGTi-R said:
U're from Malaysia by chance?
Yeah i would prefer to grind of the shims but the thing is HOW do u grind of the shim with grooves (known as "rocker arm guide" shim in the manual)?
What sort of machine u recommend to get the job done?
Pardon me as i'm not mechanically sound. Just giving suggestions to my mechanic friend who's building it.

The previous cylinder head is warped which is why i replaced it.
Just feel lost after the amount of cylinder head work such as porting, polishing, swirls and blah blah done to it only to be stopped by some 16 shims.

Oh btw are the shims used on the GTi-R the same as the GTR RB26DETT?
Take the shims to a machine shop and tell them the sizes you need them ground down to and the will do the rest for you, Just make sure you tell them the right sizes.
 
O

Olly

Guest
You could machine the back side of the shim the bit that rests on the valve cap. Or you could machine or use your thinest shim you have, measure the shim + the gap to the cam with feeller blades then - minus the clearance, and order the right shims first time. Thats the way I do it on Fords Zetec etc etc.

Olly 8)
 
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