valve clearance

[tr6tuga]

Hi fellow Trs

I'm very confused

For some time now I'm trying to settle valve clearance as per instruction on the BB,

 

- Section 12.29.48 valve clearance, set all to 0,25mm, but them when checked according to section 12.65.08, valve timing,1 & 2, should have the same clearance as 11 & 12, wich I never managed to get! even repeating the process.

That means the 4 valves should be closed? what I'm missing?

 

Is there a more compreensive step by step To do? how important is valve timming? When clearance is properly set there is clearance on 1 & 2 but 11 & 12 are slighty compress

 

thank you

[TriumphV8]

There is some misunderstanding in the manual and the basic function

of the TR6 6-cylinder engine.

 

It helps that the cylinders are paired, 1&6, 2&5 and 3&4 belong together.

If one of the fellows is on TDC he has both valves open on overlap what means

they are a little bit open. How much that will be depends how "hot" the

cam is what means the larger the advertised degrees the more they are open.

 

The carb version nearly has valves not open while the 143HP PI has about 2mm.

 

The other fellow in that position (TDC) got just the ignition and is ready

to deliver work. To do that both valves must be closed => you can set them.

 

So it is pretty normal that never 1&6 can be set or measured at one position.

 

To do the work with less chance to do something wrong proceed like this:

Number one is used for finding TDC: Remove the plugs for easy turning,

find a nice ground with some space and put in the 4th gear.

Now you pull car forward until number 1 exhaust valve opens.

Be carefull, move slowly now until exhaust closes and inlet starts opening.

When they are on the same height number 6 is ready to set up.

 

It is not necessary that it is that precise, the valves of the fellow to set

are closed over a longer degree.

 

If you open distributor you will see that the finger points on the contact

of the cylinder that you want to set up.

Edited October 11, 2015 by TriumphV8

[GT6M]

Good lord , what a palava to give to set the valves.

 

easiest is this

1 and 3 down, so set 12 and 10, this is called rule of 13

as 2 diff valves both add up to 13, simples.

 

 

And, unless ye got bran new rockers/shaft, forgit aboot setting em at 10thou.

can be any thing, even 0 thou gap if using a feeler gauge

 

but if ye no up on thee,s things, then set em all to 6-7

this should tek into account some play

 

{ This of course if its a standard cam, that needs a 10 thou gap,]

 

M

[john.r.davies]

Zero thou, Markus??

What about thermal expansion?

 

tuga,

The Workshop Manual is confusing. The Rule of 13 as Markus says is a useful way of working out which valves to set.

Number the twelve valves from the front, 1-12. You can start anywhere, turn the crank (plugs out) with a spanner, note a pair of valves (they will not be on the same cylinder) that reach maximum opening, take the number of that valve away from 13, and adjust the valve with the number you get.

I find it useful to put a blob of Vaseline on each rocker adjuster screw when I have done it, so I know when I have finished!

 

Another way is to imagine that there is a mirror across the engine, between bores 3 and 4. When a valve is fully open, set its mirror image. EG No 2 valve down (Inlet Cylinder 1) adjust No.11 valve (Inlet cylinder 6)

 

The second section of the WSM that you referred to is nothing to do with valve clearances, but is a way of checking the valve timing. If you have not had you engine apart, the ignore it! It is only of use when rebuilding.

 

John

[GT6M]

Zero thou, Markus??

What about thermal expansion?

 

0 clearance.. with feelers, can still be showing 10 thou, go figure !!!

whats the point of setting it to 10, when could actually end up wid maybe 20-25 thou actual gap.

gotta no what yer upto, and what yer up against.

 

M

[Peter Cobbold]

Anyone adjust them with engine running?

Peter

[rhine]

When I was a young teenager, was shown by an time served BL mechanic that you just get the engine to running temp and then gently close the gap to zero, with the engine stopped.

 

Not very scientific and guess you have to work quickly in a cold climate, but he did point out that this took up any wear in the tappet that a feeler gauge would bridge.

 

Wear some gloves!

 

Richard

[tr6tuga]

Thank you all for clear directions:-), I'll have a try this week.

By the way, its a 1971 PI engine tune was a terrible Mess...

This has being a "rabit chase" since last year, what started with engine misfiring/stumble at low revs, 1500rpm then perfect above

I have being all around

Electrics, dizy,pump voltage

Fuel line, tank, hoses, new prv, new lucas pump, KMI replaced MU,injectors

Engine bottom main bearings, trustwashers

Trottle tunning

Engine top, head, new valves set

Engine tune, fuel pressure, manifold depression, dizy all was check:-) but still strugling...

I'M about to send my TR to a corner as punisment:-)

[TriumphV8]

You should not forget that TR is 44 years old

and often, because it is fun to drive, it was in use all the years.

 

So more or less all the parts that can be worn will be worn to some grade.

If you look at those parts that just ex works have not been the best and most reliable solutions

they can be a pain today like the PI throttle linkage and bearing.

 

I was proud on my ball bearings and homemeade spindles but had to recognize

that the only "ready to fit" parts bought from Moss are ready for the bin after 4 years.

It was the three peace linkage kit with ball/cup connectors that got a lot of play now.

 

By the way it was not "palava" to show how to set the valves but also to

explain why cylinder 1 and 6 can never have a position to set valves.

Anyway everybody is free to decide wether the calculation to 13 and adding marks

to the rockers to avoid confusion is easier than my way to do the cylinders step by step.

 

Even the experts may find it helpfull from time time to read the basics

because camshafts have some details hidden everybody should know.

 

The hint setting the valves clearance to zero is based on a lack of knowledge.

Often found in the literature it will be never be the case that heating up the engine

will expand that the play reduces to zero. This would be a high risk because every

hammering in of the valves into the seats would immedeately destroy them because

they can not sit properly any more and get rid of their heat by transferring it to the head via seat

 

The manufacturer gives us a figure and a temperature to set it (0.25mm/cold)

What this clearance will be when hot does not matter.

The cam profile has a ramp where the valve clearance is eaten up smoothly

before the valve is opened.

 

If the play is too large the valve train meets the profile at high acceleration and is hammered open

what makes noise and can destroy the valve train.

When the play is too small the valve is lifted too soon and only a little bit and the gas blows

over the seat like a torch and destroys valves and seats.

 

So both is very bad and the size and form of the profile ramp is only known by the cam maker

It is best to follow his recommendations because there is no advantage to go an individual way.

 

Also the benefit is that the manufacturer has in mind that little changes in play may not bring

the valve train into the critical situations explained above.

There is some space over the ramp where the valve train can meet the cam perfectly that under

normal conditions between two cycles of valve setup this area will not be lost.

[GT6M]

Stilll want to set em to standard, as said, unless ye no what yer up against, total waste of time

 

 

M

[TriumphV8]

This picture shows total scrap.

 

As the rocker slides forward/backward over the valve tip when

it opens it needs a smooth surface on both sides otherwise it

will frett and also stick in the recess and move the valve towards one side in the stem.

 

Both is very bad for an engine and should be renewed as soon as detected..

 

Keep in mind that others think even the sliding over the tip of a perfect system

is not good enough and they fit rollers with needle bearings at that place!

Edited October 12, 2015 by TriumphV8

[GT6M]

No that picture dont show total scrap.

that pic shows a indented tip. which is why folk cant set their gaps correctly.

 

Butt, if the case hardening aint gon, and the bore is OK

then a re faced olde worn one will be alott lott better than a brand new one.

and if bores gon, then a re bush and re face is still better than a new one.

 

A new one will just doo as in the pic v soon, esp wid bigg cams and gaps.

an olde one re faced wont.

 

M

Edited October 12, 2015 by GT6M

[Steves_TR6]

Interesting thread!

 

The build notes for my engine, from 1997......., state "24thou all around"

 

Which I take to mean the same clearance for inlets and exhausts.

 

I've yet to touch the valve clearances, to my shame in three years of ownership! Although it put out more than 160bhp at the spring rolling road event at Enginuity so can't be too bad?

 

What do we think of 24thou clearances?

 

Steve

[rhine]

Steve, I think that if your engine is pushing out 160BHP at the rear wheel, then you tore up the specs in the brown book some time ago, so normal rules don't apply to you.

 

I am not an expert, but imagine that as a part of your engine tune and subsequent setup, new rules for your engine were created at the shop.

 

160BHP! Remember being impressed when family 6 cylinder 2.2 litre British Leyland car arrived at home with a published 120 BHP. Anyone recognise it?

[peejay4A]

Princess?

[GT6M]

If its got 24 thou gaps, then its an after market cam

prob a Kent th 6 0r 7

 

and if not got good rocker tips, then you will have set em even bigger.

 

Look at the pic oft rocker tip

 

10 thou indent + 10 thou clearance gap, done wid feelers = 20 thou gap.

Not the 10 thou its supposed to be.

 

this is why I say set em to 6 ish if worn, and with oot checking to see if any indents thea

 

As an indent of say 4 and a feeler gap of 6 = 10, which is factory.

butt, really need to slacken adjusters off, turn rocker upside doon

see whats what, and set accordingly.

 

and a clock gauge,or a finger gauge, set ont tip is best way.

when ye got a ruff idea of hoo much an indent, then just set rest to the first one.

 

Tip, set em to 8, when tightened up, ye will fin its gone to 10

due to tightening the nut up

And also any ive ever done, the gap gets bigger when hot, not smaller

So another reason to get em right.

 

Also note, that if yer gaps too bigg , then it also decreases yer duration,

the bigger the cam, the moer effect it has.

 

M

[RogerH]

Just to go sideways for a moment .....

On my 4A I had the rockers set to 10 for 3 or 4 years and they were nice - no excess noise, no funny goings on.

I popped the car into a garage for a quick tune prior to the 2010 RBRR and they pointed out that they had reset the gaps to 0.010" - odd I thought.

 

When I got home I found that they had reset them to 25. Rubbish I thought....... until I realised that I was using a metric feeler set. aaarrrggghhh

10= 0.1mm = 0.004"

0.010" = 0.25mm = 25 (on the feeler guage)

 

Always check your tools.

 

I did think 0.004" was very good though

 

 

Roger

Edited October 12, 2015 by RogerH

[rhine]

Very close PeeJay. Wolseley six. OHC and burnt oil like it was petrol, but back to TRs.

 

Richard

[Tom Fremont]

Hi TR6tuga,

 

For valve adjustment refer to 12.29.48, not 12.65.08 which is for valve timing; a different exercise.

 

Cheers,

Tom

[tr6tuga]

Just a update, spent same time setting the clearance to just "holding" 0,25, new spk ngk ready for firing up, after social obligations:(

Thankyou all for the leads

chers

Jose

[GT6M]

so ye set em to 25 MM, but was this across an indented rocker,

or did ye set em to 25 wid a clock gauge

or did ye not need a clock gauge, as ye have looked at the undersides of the rocker,

and seen there no indents..

 

If there are indents, and ye set em wid a feeler gauge, then ye aint set em to 25

ye set em to 25, Plus what ever the indent is,

25 + say,15 indent = 35 actuall setting, follow!!

 

M

[TriumphV8]

I put this in a translator!

Was a nice result!

[Andy Moltu]

If your rockers are that worn (it's no big deal to take them off and check) polish them flat or replace then or use a "clickadjust" tool.

 

Setting rockers to minimal clearance when hot might work with a standard cam, however a great many cars have after market cams. Thes may well need to run at much wider clearance for a number of reasons:

 

1) To gain the correct opening and closing times for the profile for maximum power/efficiency.

2) To hit the correct point on the slope of the cam to avoid excess loading damaging cam or followers.

 

I have translated this into a variety of dialects in case some of you struggle with plain English

 

Cockney:

If yor rockers are that worn (it's no big deal ter take them off and check) polish them flat or replace then or use a "clickadjust" tool.

Settin' rockers ter minimal clearance wen 'ot might work wiv a standard cam, however a great many cars 'ave after market cams. Thes may well need ter run at much wider clearance for a number of reasons:

1) To gain the correct openin' and closin' times for the bloody proRoyal Mile for maximum power/efficiency.

2) To 'it the chuffin' correct point on the slope of the bloomin' cam ter avoid excess Old Kent Roadin' damagin' cam or followers.

 

Elmer Fudd

If youw wockews awe that wown (it's no big deaw to take them off and check) powish them fwat ow wepwace then ow use a "cwickadjust" toow.

Setting wockews to minimaw cweawance when hot might wowk wif a standawd cam, howevew a gweat many caws have aftew mawket cams. Oh, dat scwewy wabbit! Des may weww need to wun at much widew cweawance fow a numbew of weasons:

1) To gain the cowwect opening and cwosing times fow the pwofiwe fow maximum powew/efficiency.

2) To hit the cowwect point on the swope of the cam to avoid excess woading damaging cam ow fowwowews. Oh, dat scwewy wabbit!

 

Swedish Chef (As all of us Scandinavians talk like this)

Iff yuoor ruckers ere-a thet vurn (it's nu beeg deel tu teke-a zeem ooffff und check) puleesh zeem flet oor replece-a zeen oor use-a a "cleeckedjoost" tuul.

Setteeng ruckers tu meenimel cleerunce-a vhee hut meeght vurk veet a stunderd cem, hooefer a greet muny cers hefe-a effter merket cems. Um gesh dee bork, bork! Zees mey vell need tu roon et mooch veeder cleerunce-a fur a noomber ooff reesuns:

1) Tu geeen zee currect oopeneeng und cluseeng teemes fur zee pruffeele-a fur mexeemoom pooer/iffffeeciency. Bork bork bork!

2) Tu heet zee currect pueent oon zee slupe-a ooff zee cem tu efueed ixcess luedeeng demegeeng cem oor fullooers. Um gesh dee bork, bork!

[barkerwilliams]

Andy,

 

Aye up lad, I'll go t'foot of our stairs, that's great that is.

 

 

Alan

[Bodiam]

Andy - simply brilliant!

 

John