Valve guides - K-line

[alexd912]

Hi there,

After removing the heads from the 600 OHV I found that the valve guides on some of the valves appear to have quite a lot of play in them.

I have seem some recomendations of the K-line inserts:

http://cylinderheadshop.co.uk/blog/2010/05/22/k-line-guide-liners/

I just wondered if anyone had any experiance of these and also what sort of tolerance are required for the guides?

Best regards

Alex

[Doug]

Alex,

These are phosphor-bronze liners, are are best suited for engine with positive oil lubrication to the top end. I think they will be prone to seizure in your application. I have seen folk sprinting DT machines with bronze vailve guides, but they have the advantage of being able to directly apply a few drops of oil to the exposed valve stem periodically. I think you will be better off with the original cast iron, which is more tolerant to erratic or nil lubrication. I do not know of any cast iron valve guide liners. I have heard that the Norton Commando valve guide has the right outer diameter, but as it lacks a flange a snap ring groove needs to be added. Also I belive these are used with a Triumph and/or BSA valve which has a smaller stem diameter. But one can ream the guide out to a larger size to suit, of course.

-Doug

[alexd912]

Hi there,

Is it not possible to increase the tolerance a little more?

It appears that only one or 2 of the guides would need replacing, but I suppose its better to replace all at the same time.

Only reason i ask is that we have a local company here that specialises in fitting the K-line inserts.

Br

Alex

[eddie]

Hi Doug and Alex,
                           Commando valve guides seem to be available in several forms - both cast iron and bronze in early and late type (and oversizes as well). The guides I have used in my sprint engines are machined from bronze inlet guides intended for the '73 to '77 models. They have enough of a head to ensure they are fitted to the correct depth. Another problem which has occurred since the introduction of unleaded petrol is that the new valves are made of a material that is prone to 'picking up' in cast iron guides unless the stems have been treated to overcome this. Both the valves and guides I am using came from Kibblewhites in the States - in my 600, as I say the guides are Norton and the inlet valves are the ones with oversize heads that are intended for use in a late 500 unit Triumph. The exhaust valves are from a BSA B40. Just a lttle trimming is needed on the ends of the stems to get the correct rocker angles. All these are kept under control by using springs, caps and collets intended for use in a 650/750 unit Triumph.

                      Regards,
                                     Eddie.

[richson]

As Eddie says, the Commando guides are available in cast iron and bronze.
In that engine if the iron guides are used which to an extent self lubricate, rubber seals are fitted over the stems to reduce oil consumption. If you fit the seals to a bronze exhaust guide it will wear out quickly (I know this for a fact), so I would say that using the bronze guides without positive lube is asking for trouble.

Cheers,

Neil

[alexd912]

Hi there,

Just an update but I came across this this site today that have a whole range of cast valve guides:

http://www.motorcyclestorehouse.nl/index.php?action=product-list&searchType=brands&productbrand=145&b=0

Am I missing something here or could these suit my early 600 OHV? I have no idea of the measurements required until I remove the old ones.

Sorry for all the questions...

Best regards

Alex

[Doug]

Alex,

The valve guides for the 1931-35 enclosed rocker models are very similar to the DT models, but they are slightly longer. The various posts on substituting Norton Commando valve guides for DT here on this Forum are applicable. The following shows the nominal dimensions, which you would have to alter the fits to suit your situation. For instance my guides measured 0.626 inch diameter, but this gave what I felt was an excessively tight press fit in the head. Other DT guides I have measured are more typically 0.6255 inch diameter.

-Doug