rockers

[briandr]

Hi can anyone help me with my rockers I have 1275 head on 1098 block properly machined (earlier post),but on assembly of engine and setting tappets I realized that they are all not hitting square on ,how do I get this right?[frame][/frame][frame][/frame][frame][/frame][frame][/frame] I have not split the rocker shaft its as it was when I bought car.

[philthehill]

You will have to fit/remove/move the shims around to bring the rockers over the centre of the valve stem. Obtain shims/washers from old rocker assys if required.
i.e. Number 1 rocker (see photo) move the shims/spring to the other side of the rocker but leave the end washer in place.
Make sure that the rocker tips are not worn before re-alignment. If they are it will not be wise to move the rocker out of current alignment. If the rocker tip is excessively worn you may have to fit new rockers.
In extreme cases you may have to remove metal from the side of the rocker shaft pillar to obtain correct alignment but I would not recommend removing metal from the side of the rocker.
Rockers out of alignment can lead to offset wear of the rocker bush and rocker shaft so it is best if they can be centrally aligned with the top of the valve stem.

[bmcecosse]

It's well detailed - I mention it every time the 940 head is discussed....you need to re-align the rockers on the shaft - so they DO press squarely on the valve tips. Some filing - some adding of spacers (washers) till you get it spot on.. - very satisfying when you get it right! Alternatively you can use the grim sintered rocker set from a 1275 engine - as long as not using silly high lift cam - or uber strong valve springs. Did you machine the seats to sink the exhaust valves? If so - be sure to add spacers (washers) of whatever thickness you machined off, under the springs to keep the compression correct. If the rocker tips are worn (as mentioned above by Phil) just stone them back to the correct profile.

[Declan_Burns]

This explains it although I fitted pressed steel rockers in the end[frame][/frame][frame][/frame][frame][/frame]
Regards
Declan

[philthehill]

To add to bmc's comments above regarding wild cams and strong valve springs; if you are contemplating using those parts then it is best to use the steel rocker shaft pillars from the Cooper 'S' (all variants) because the standard pillars have been known to fracture and fail. Under NO circumstances use the alloy rocker shaft pillars as they WILL definitely fail!

[bmcecosse]

Neither wild cams nor strong springs are suitable for a 1098 - since it must not exceed 6000rpm. The large valves on the standard lift give plenty of extra air flow!

[briandr]

Thanks folks I have not done any work on the head its as came on car,just decoke grind valves ect.will follow advice given thanks to all.

[moggiegeek]

Brief Question.......Will using the sintered rockers will obviate having to shim and grind to get the alignment right as you would have to do if using pressed steel rockers?

[bmcecosse]

Well - yes - that was MG/Rover's answer to the problem - the wide rockers just operating off centre.... But it is far from an elegant solution...

[philthehill]

May be of interest:-
I have recently managed to obtain a 'as new' set of 1.5 valve rockers but the rockers were as described above by the OP - not above the centre of the valve stem.
The only way to get the four of them in line was to machine the side of the rocker pillar - similar to that described by Declan above.
The steel pillars that came with the set when machined would still not allow the rocker to fit centrally over the valve stem as the adjuster end of the rocker fouled the pillar.
Having tried several different pillars and different ways of machining them I decided to use the forged steel pillars as used on the early Minor engine. These pillars have the same forging number 12A210 & 12A211 as used on the Cooper S but without the chamfered corner around the 5/16" stud.
The forging around the 3/8" stud hole is slightly thinner so allowing the adjuster end of the rocker to move closer to the pillar centre and so allowing the rocker pad to move closer to the centre of the valve stem.
I have allowed 0.020" as a nominal clearance between the adjuster end of the rocker and the rocker shaft pillar. I can shim if necessary (shims available from Mini Spares) to increase clearance if required.
The sintered steel pillars are no good for machining as the sintered steel will not allow a clean cut, blunts the cutting tool and leaves a rough finish which is no good.
Using the 12A210 & 12A211 pillars resulted in a very good surface finish.
The other side of the pillar was faced off as well because when forged the rubbing surface of the pillar is slightly off square to the rocker shaft so has only partial contact with the rocker.
To set up the pillar in the lathe independent 4 jaw chuck I used the stub end of a good rocker shaft held in a tailstock chuck see below:-[frame][/frame][frame][/frame]

[don58van]

Roy

When you mention stoning the rocker tips, how would I go about doing that?

Cheers
Don

[bmcecosse]

Simply by hand rubbing them on a knife sharpening stone - until any 'dent' in the surface disappears. And of course - retain the original slightly curved surface while doing so.

[les]

I've done this myself in the past but have wondered at the time whether the surfaces are case hardened, if so then there is a danger of breaking through this.

[philthehill]

Les
The tips of the rockers are hardened and only the slightest imperfections can be removed without effecting the hardening.
Any deep indentations found in the tip of the rocker caused by contact with the end of the valve stem does mean replacing the rocker.
Whilst deeper indentations can be honed/stoned out it does mean a reduction in the life of the rocker and the more of the pad honed/stoned off the shorter the life of the rocker.
Phil

[bmcecosse]

Since it has dented anyway - there is nothing to lose.

[philthehill]

Once you get past the hardened surface all you are left with is softer metal which will slowly grind away and those grindings will get into the oil, circulate through the engine and not do the engine any good.
Having seen the results of letting rockers wear past the hardening - it was not a pretty sight and was expensive to rectify.

[les]

Thanks, confirms my suspicions. I suppose it was obvious really, on reflection, to have a hard surface.

[bmcecosse]

Never had any problems with that - but only ever did it with the much better pressed steel rockers - would not do it with the sintered rockers - which I never used anyway!

[don58van]

Simply by hand rubbing them on a knife sharpening stone

Thanks for your reply, Roy.

I was wondering whether anything more high-tech than that is needed.

Don

[bmcecosse]

Ohh I've no doubt there are many hi-tech ways to do the job - hand stoning has served me well over the years - it's only a very slight 'denting' that can be evened out - anything deep and the rocker should be discarded. It usually only occurs with 'extra strong' valve springs and high lift cams. Not something to be recommended on an otherwise standard 948 or 1098 engine.