shims (as per usual)

GTIR-LOZ

New Member
hi have stripped down my head for valve stem replacement and am getting confused by the shimming etc questions are

1. the shims are the smaller round shaped things ontop of the valve and the castle shaped things are the rocker guides?
2. the rocker arms have numbers under them is this to get the correct size for adjustment as the shims have no numbers on them?
3, are the shims/rocker guides all the same size and the adjustment done by replacing the rocker arm?
4, do the shim and the rocker guide have to be matched and are they all the same size from factory?



also 1 castle thing (guide?) is broken on the corner is there a standard size to replace it with?

with bobby's shimming guide when you measure it do you cut 2x feeler to size 1 for the guide and one for the shim or if not which one do you do?

it all gets very confusing
 

stumo

Active Member
1. yes they are the shims

2.the numbers don't have any relation to shim sizes

3.the shims (both flat and castle ones) have different thicknesses and are probibly different for the same rocker**

4. as above there's lots of different sizes of shims.

** they can be different due to how far the valve has shrunk into the head or how much the valveseats have been cut or the length of the valve (most likely all will be the same but you never know) etc etc

If you change cams you will most likely find that all the shims will need changing, it's a pain in the a$$ job
 
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pulsarboby

Guest
you need to put all the shims / rocker guides back where they came from first of all.
then bolt the cams on and torque them up to correct torque
once you have done this you can then start to shim them up.

you need a piece of paper and a pen first of all
write down 1-8 inlet in 1 column, then 1-8 exhaust in another
get some feeler gauges and measure the distance between the rocker arm and the cam on say number 1 inlet (measure at tightest point where cam meets rocker, normally the edges)
the valves should be in closed position ie off the lobe.
off the top of my head i think clearances cold should be 0.17. if you have 0.20 clearance then mark down the reading on a piece of paper next to 1 inlet, the difference on that valve will be 0.03 so you need to cut a circular bit of feeler gauge with o.03 marked on it, then force the valve spring down and lift the shim out, place the feeler gauge bit you have cut off firmly inside the shim so its flat, then replace the shim.

if the bit of gauge falls out then you have cut it too small, make sure its a snug fit!

sometimes its easier to take all the readings then slacken off the cams again, that way its easy to remove the shims and you can do all of them at once.

DONT make the clearances tight, ie if the difference is 0.03 dont put a 0.04 piece of gauge in there!!! this will not allow valves to shut properly and you will end up with burnt out valves, better there a bit noisy rather than quiet and over adjusted!
hope that helps, its the simplest way i can explain it

as stumo says its a real tedious job, but take your time and make sure its done correctly, a days work to get them right.
 

GTIR-LOZ

New Member
do you have to do both the shim and the guide or just the guide and if thats all there is then why do the rocker arms come in different thicknesses as well you would think they would all be the same size???
 
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pulsarboby

Guest
the rocker guide is a shim, just because it has 2 locators on the sides, dont be fooled into thinking anything else! it does exactly the same job as the one sitting next to it.

if im honest i didnt know that rocker arms came in different thicknesses! this will of course effect the valve clearances if you dont get the same size as the ones already fitted to car, can only assume that they are for hugely different cams to take up excess clearances.
 

GTIR-LOZ

New Member
just when i took off the arms there were different numbers underneath them and i measured them and they seemed to be different thicknesses
this is the thing that confuses me lol

so should both the shims be the same value? i.e shim up the guide then check and correct the other shim to make the clearance the same over the whole lobe?
 
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pulsarboby

Guest
yes both shims should be the same thickness as both inlet valves work in unison per cylinder
 

stumo

Active Member
Bob, that's not necessarily true, you can have different thicknesses due to different installed heights of the valves.
 
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treemonkey

Guest
sorry to dig this old thread up. What should the valve clearance be in thou's. I have a range from 5 to 8
 
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