HELP - Valve Clearences

stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
MESSAGE TO MODS: PLEASE ALLOW THIS POST TO STAY HERE FOR MAXIMUM READER VALUE AS I'M DESPERATE TO GET HIS JOB DONE AS SOON AS POSSIBLE

Does anyone on here have any first hand experience at doing the valve clearances from scratch. Please read on...........

Why aren't these bloody shims/guides numbered as they say they are in the manual :x

What I've got is:

Rebuilt engine (all shinny and new),
rebuilt (flowed & ported :twisted: ) head with new exhaust and inlet guides e.t.c.
Original valves and valve seats cleaned up
All valves lapped in and fitted with new springs
Head torqued down with 1.2 Tomei gasket
Pair of 164 HKS cams

all my own work so far :D

but I have this "PIC & MIX" BIG BAG OF SHIMS AND GUIDES (collected over the years)

I'm all ready to go but...............maybe I'm being a bit thick but reading the manual is fine until I get about half way through the "Adjusting the valve clearances" section, then my brain just goes to mush :???:

What I need is someone with first hand experience at doing this to write a quick guide, but in layman's terms, something we can all understand.

If anyone can help, please

Steve
 
T

Toady

Guest
lol! ive been in my garage doing these over the weekend too mate! my engine sounds same as yours so far too, without the gflowed head! :wink:

What exactly ru having trouble with? Is it measuring your valve clearances or measuring the shims? as i know what you mean...they are'nt labeled with sizes! :roll:

What ive done so far is assemble my head/cams etc. Checked the clearances- which are all out. Ive written them all down in order so i know how much clearance they all have. Next ill be taking the cams out to remove the shims one by one, and measure them with my vernier. Ive drawn a diagram which ive written the clearances down on, and the shims will be placed on the diagram with the size also written down. This way knowing what the standard clearances should be (0.21 - 0.26 cold) I can work out how far out they are. Ie, If one clearance is 0.33mm then it is at least 0.08 too big, therefore I need a shim that is 0.08mm bigger.

Does that help at all?? :?
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Yes, that makes sense !!

Well, I sat down last night and measured each shim and guide with a dial gauge.

I set up a dial gauge on a magnetic stand, then placed an inlet valve standing up right under the dial gauge and set the gauge to 0 resting on the top of the valve stem. Then placed each shim/guide individually on top of the valve stem and placed that under the gauge and recorded the value measured, cross referenced the measurements with the guide in the manual and put them into bags with the measurement marked on the bag. Then because I'm a glutton for punishment did then all again just to double check (took 2 1/2 hrs to do about 40).

Now, I do have a head already built up and correctly shimmed with my 264 cams in it (but it's done 90,000 miles, the cams only about 8,000 miles) so what I thought of doing was just swapping all the bits over exactly as they are to my new head, this I thought would at the very least, give me some sort of starting block.
When speaking to various tuners it has been suggested that they always build the head up and measure up cold, on the bench as doing it hot is just not a practical option.

You have PM

Steve
 
T

Toady

Guest
That sounds about right mate! I finnished mine tonight, got all the clearances on the shims to 0.23mm and all the clearances on the guides/cam to rocker to 0.18mm! wahoo!

PM back at ya steve! :wink:
 
S

Shaun

New Member
So does this mean we now have 2 forum members that can fit and shim cams for the rest of us :?: :eek: :eek: :eek: WAHOOOOOOOOO :eek: :eek: :eek: :lol: :lol: :lol:
 
J

Jobi Joba

Member
When you have a gas flowed head and more important,when u've just cleaned your valves and valve seats,your have to set up the valve clearance.

The best thing to do is to choose 8 flat shims and 8 guide shims with a rather small thickness,to fit them on the head,to install the camshafts and to measure the clearance.

As I don't know feeler gauge which are small enough to measure the valve to rocker clearance for the guide shims,the best thing to do is to measure the camshaft to rocker clearance,on each side of the cam.

the std clearance is 0.14 to 0.17mm when cold.

Take care when you measure the clearance:when the valve is 100% closed,I found out that the clearance value doesn't remain constant and that sometimes you have about 0.02 to 0.04mm variation.So when measuring the clearance on one particular cam,check the clearance for various cam position.

After doing this measurement (I have a Word document which can help to write down clearances clearly if u want) u remove both camshafts and measure each shim individually.

The thickness is measured between bottom of the shim and where the rocker arm sits.If you want to get the Nissan thickness value,just remove 3mm from the measurement.

BTW,don't forget to multiply the gap between old and new shims by 1.5 before removing this value to the measured clearance...cause the clearance is measured between rocker arm and camshaft,whereas you act on the shims which sit on the top of the valve.

(valve to rocker clearance is 1.5 bigger than rocker to camshaft clearance)

After having chosen the new shims,just fit them on the right valves and replace the camshafts.

Done.


NOTE:don't be afraid to set the clearance to 0.10mm,it's smaller than std but the clearance are bigger when hot.U'll end up with a quieter engine,less stress on the camshafts,etc...And if you have stiffer valve springs (Jun,Tomei) or mega stiffer valve springs (Ferrea),you'll have to set the clearance to approx 0.07mm when cold.


time needed for the job:
- 1hr for measurement
- 1hr to remove both camshafts
- 1 to 2hr to measure the old and new shims thickness and to do all the calculation job (the more accurate you wanna be,the more time consuming this operation is)
- 1hr to fit the new shims and to fit the camhafts
 
T

Toady

Guest
yep! it sure IS time consuming!lol! 8) oh and i meant o.15 not 0.18! :oops:
 
B

briitts

Guest
HOLY FOOOOKKKKKK!

I am so screwed. :cry:

I think I will just leave my head as is, yes.
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
How easy is it to get new shims
Click to expand...
Yeah, good one :lol: :lol: :lol:

From Nissan it would all depend on which ones you want, some are "sometimes" available and some are never available and at £20 each I for one would ask around before approaching Mr Nissan.
 
T

Toady

Guest
didnt jimmy mean how many do you need for the engine? ie...16....16 valve??? :? :lol:

steve have you worked out what sizes you need yet? as ive got a few to swap with you if you need. 8)
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Nah thanks mate, all done now. Got them all between 6 & 6 1/2 thou. Engines back in and nearly ready to fire up.

Cheers for the offer anyway

Steve
 
T

Toady

Guest
nice one mate! glad to hear it! so youve over taken me now then!!! lol! :lol: mines still on the engine stand! :roll:
 
stevepudney

stevepudney

GTiROC CHAIRMAN
Staff member
Well, after battling with the valve clearances, the engine is now all built up and bar a few hitches in the car and all running (well, I'm amazed even if your not!!).
When I was setting the valve clearances I was advised that I could build the head up off the block then mount it on the block put the cams in and set the clearances when cold to 6 thou (0.15mm) and thats what I did, ish.

Once the engine was in and all connected up I did all the fluids, filled the gearbox and transfer box with Silkolene silk tran 5 and the engine had a generous helping of a cheap 10w - 40 Mineral Multi grade just to start of the run in.
On attempting first start up, I detached the HT lead and pulled the fuse to the fuel pump, then turned the engine over via the starter motor a few times until some oil pressure was visible on the gauge, this went up to the 2 position on the standard gauge, I then reattached the HT lead and put the pump fuse back and started her up. Holding her at about 2 - 2500 rpm for a minute or so to take any stresses away from any new parts that needed a quick bed in and after the plumes of steam and smoke coming from the greasy hand prints all over the manifold e.t.c. had gone I could concentrate on what what going on and what it sounded like. The oil pressure went up to about 6 at 2000 rpm and once warm settled at about 3.5 on 950 rpm idle.

My first impression was that the top end was noisy with more noise than I expected coming from the rockers. Next I noticed a water leak coming from the back of the block :cry: , I knew what that would be, I must have forgotten to do a clip up properly, that started pissing out in the end so I switched her off.

My question is (to those that know), I know that I was a little generous with the valve clearance gap, I was told 6 thou (from a reputable source) but I was also told 7 thou and even 10 thou from others, so armed with that information all my clearances were set between 6 & 7 thou (cold), the question is, if I leave the clearences at that will I be loosing out on anything or doing any damage. Also on tha crap oil, does the oil pressure sound alright as I was concerned it was a little low.

Your quality replies are eagerly awaited.

In the meantime I'm now going off to take the engine out again to do up the suspected loose water pipe down the back of the block :cry: :cry:

To be continued later..........................................
 
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