Recommendations for doing valve guides

[IanHood]

I have a couple of heads that need valve guides doing. Can anyone recommend someone in the UK who could do that?

Ian

[Duccout]

Hi Ian,

Any engine reconditioners who have the equipment can reline the guides.



Cheers,

Colin

[Dave354]

Hi Ian,
I found an engineering workshop down here in Cornwall who rebuild many engine types (tractors to trucks and everything in between) . They put in new guides supplied by Nigel and even reground and lapped the new valves for me. A great job. I think any competent engine machine shop would be able to do the job, but if you can’t find one I can pass their details.

Regards

Dave

[themoudie]

Like Colin, I would suggest that lining the guides, with K-liners is preferrable to knocking out the guides and then installing new guides.

There is no chance of spalling aluminium that can occur when removing the guides. I had a Ducati head renovated, replacing the worn guides and upon removal a large hole in the head casting was revealed! So this had to be welded up and machined, before the new guides went in.

The whole re-lining process can be much quicker than the installation of new guides.

The main thing when having the K-liners fitted is to ensure that the clearance between the valve stem and guide bore is sufficient, too tight and you get rapid wear of the guide liner.

Once relined, or with new guides installed the valve seats may require a touch/re-angled cut, to ensure squareness to the guides, afore re-grinding and lapping the valves.

Use somebody local if possible, the personal touch/conversation, with the engineer can make all the difference.

Good health, Bill

[gregwils]

Interesting, I had never heard of K-liners until just now. Are there reasons for choosing K-liners beyond replacement being less invasive or potentially destructive? Do they have similar wear characteristics? Can the guides be worn too far for K-liners? Thanks.

[Duccout]

Greg, afaik (and I could be wrong - I know that Eldert does not like guide liners) apart from the danger of damage to the guide bore and mis-alignment when replacing guides, the liners have oil grooves reamed into them, allowing closer tolerances.

Cheers,

Colin

[themoudie]

Aye gregwils,

Wear characteristics of K-liners are every bit as good, if not better than ordinary phosphor bronze valve guides, due in part to the oil retention grooves within the bore. Many commerecial vehicle engine re-conditioners use them because of their known service longevity and ease of renewal.

Whilst you may be advised that you are able to have closer running tolerances between a K-liner valve guide liner and the valve stem, this can lead to scuffing and premature wear between them. This was a problem that I had with my '74 450 MKIII head guide liners after they were installed by a widely advertised cylinder head "specialist" in the UK. I would not advise there services.

It would appear that whilst the valve guides had been lined, genuine K-liners may not have been used and some guides and liners are manufactured with a high nickel content for economy of manufacture. CAVEAT EMPTOR! And the measured running tolerances in my cylinder head were "tight" (0.0015").

So, my local engineering shop owner, who runs a very nice BSA Rocket Gold Star and does cylinder head work on car rallying engines, accepted the job of removing the old guide liners, re-boring the valve guides perpendicular to the valve seat to accept genuine K-liners and after installing and trimming the liners, they were lightly honed to give a running tolerance of 0.002" between the guide and the valve stem. The valve seats were then lightly kissed to achieve a good seal between the valve head and seat, this being vacuum checked and found to be perfect.

I installed the valves myself and used the 'Viton' guide seals. So far, after over 10,000 miles use, I have not had any problems and there is no blue haze on the overun.

If you should want more information about the K-liner valve guide liners then I attach a link for information (this is not my local engineering shop):

K-line_article

Good health, Bill