Valve adjustment?

[zippy500]

The tappets have always sounded a bit noisy, so the weekend I set about to readjust them( using rule of 9 and setting to 12 thou as it stats in the manual).

fine all set up, rocker cover back on- start engine noise is still there!!!

Talking to a chap at work he tells me that although the tappets are correctly set, that over time where the rockers have been hitting the valves, they have created dents in the rockers, and suggests that I remove the rockers and reshape/grind them flat again.

Or is it ' a noisy tappet is a happy tappet ' and leave well alone.

what are your views on this.

Cheers, Andy

[moggyminor16]

there is a saying "if it is working leave alone "

yes i know what you mean i have the same on mine and the rockers do have a slight indent on them there for i messured the diffrents and was about 1 so i just went to 11 thou
now its has not gone but a lot better when you do this if you do watch the tappet go down then up making sure the valve opens fully and closes fully if not then you will get a lot of problems trust me been there middle lane of the m25 not good

[Packedup]

If you put the feeler guage blade fully through the gap, then any wear in the rocker tips won't be accounted for - I've got 12 rockers like that, all correct to tight when checked, at least 6 are out, with a couple being very out

It's worth trying to set then using as little of the "width" of the feeler as possible, but an alternative if you can find one is a Gunson's "Clikadjust". I've yet to get my hands on one, but in theory I think they should get the gap right even accounting for wear in the rockers

I also try and work out by eye (withthe engine running) and ear (with a bit of fish tank tube) which ones are the loudest and then knock a thou off a time till they seem quieter, but I don't like going more than 2 or 3 thou under spec that way as it seems a total guess/ bodge

I suppose the one good thing about the indentations are there should haeve been a lot of "work hardening" over the years to get them in that state!

[Alec]

Hello Andy,

obviously new rockers (which may also need a new shaft, if that is also worn) will quieten everything up.
It certainly is feasible to grind the rockers as a stop gap, try to only grind the area which does not contact the valve stem tip, (the worn area) as that will already be accurate as far as radius is concerned, you will never get that right by freehand grinding.

Alec

[Willie]

Might I suggest that the way to get an accurate gap setting on worn
rockers is to grind the edges of the feeler gauge so that it is slightly narrower
than the width of the valve top. It will then sit in the correct area and give the
correct reading. No dismantling required.......think simple!

[bmcecosse]

You can 'stone' the ends of the rocker pads smooth - ideally this is the way to go. Be very wary of setting the gap too small - very easy to end up with a burned valve. I set inlets to 12 and exhausts to 15 - to allow for the additional expansion of the ex valves which obviously get plenty hot. The 'tappet' noise is often caused by wear in the rocker shaft and the bushes. Don't worry about it - think of it more as a nice well-oiled 'clickety whirr' sort of noise!!
Si fractum non sit, noli id reficere.

[wanderinstar]

Roy,
Si fractum non sit, noli id reficere.

Does that mean, if it aint broke, dont fix it

Ian.

[bmcecosse]

Exactly. My moto!

[les]

Certain cams require 15 thou clearance, but the 1098 should be 12 thou for inlet and exhaust, the designers worked all this out, allowing for expansion etc. If it works alright don't alter it!!

[Onne]

Isn't it motto?

[Alec]

hello Willie,

your method may work but very often the indentation is at both sides and or front and back so a slim feeler will nor always do it.

Alec

[Willie]

ALEC... well it works for me. If I have a persistent problem with identifying
'tappet' noise I also set the valve clearance with the engine running, this can
be very effective. As a point of interest I have always understood that the
rockers were 'case-hardened' and should therefore never be resurfaced as
this would remove the hardened layer. Is this not correct?

[Alec]

Hello Willie,

yes, I also believe that the rockers are case or surface hardened, and you will note that I said grinding is a stop gap.

Alec (note lower case)

[Packedup]

Also, if the rocker tip has worn away, then though it'll be work hardened, any trace of factory hardening that might be removed through grinding is already not there anymore!

[bmcecosse]

Which is why I said 'stone' the rocker tip. The idea being to remove the metal protruding either side of the wear patch - but not to actually touch the wear patch! Far better to givce the ex valves a little extra clearance at 15 thou - this engine was designed way before lead-free petrol - and the ex valves can get very hot. The A series actually gives MORE power on big valve gaps - it 'snaps' the valve off it's seat and this seems to get a tiny bit more power.
Yes Willie - it should be MoTTo - I had a long hard day yesterday, forgive me for being human and making the odd mistake.

[Onne]

Oi!

[les]

I sometimes marvel at where some of these ideas come from, I thought that the valves do fully open if the valve clearance is increased, if anything losing power! I would also say that a valve would 'snap' off it's seat, as you put it, as soon as the rocker hit the valve stem, no matter what the clearance.

[bmcecosse]

Ah but the ramp on the cam is very shallow at that point - larger gap delays the contact point very slightly - so further up the ramp. The effects are very slight.

[Willie]

BMC concentrate...I made no comment about 'motto'.

[bmcecosse]

Indeed you did not - it was someone else!! I was answering you both on the one thread. Sorry if you thought I was getting at you - in fact I was only joking really, my speling is terible.