Norton Jubilee Valve guide size

That's interesting. Are they new guides? I ask because I bought some from the NOC shop and they are loose in the head of my Jubilee. Of course that could be due to wear in my heads but I am wondering what the solution might be. I can push the guides in by hand!

Not much point giving you the dimensions for my heads and guides if they are worn or undersize.

Dennis

0.5010" - 0.5015" = original size of valve guides

Thanks for your kind offer. I have used some special Loctite bearing retainer and I hope that will work. Good luck making oversize guides. There could be a market for them :-)

Dennis

.... - try having the outside of the valve guide knurled. Its an engineering technique to take up slack.

Here is some reading material on the subject:

https://www.hobby-machinist.com/threads/is-knurling-ever-a-workable-solution-for-bad-fit.75110/

Is that possible? 

Personally if no oversize guides are available, then it would be far better getting them plated with copper. If worried about them dropping through, machine a small groove in the guide where it comes out at the top and install a circlip. To go to one better with this, make a new spring seat shaped to hold the circlip down. Guide won't be going anywhere then. Remember that the guide helps get rid of a lot of valve heat too.

Please don't bodge it though, you may well regret it later.

Regards, George 

I’m sure it would be easier to find another head, they are fairly common. I may even have one! 

Dan 

Doesn't Loctite offer a high temp option?

If they do I would recommend going in that direcrion

Mike

The suggestion that knurling the O/D of the guides is not good idea.  The fit of the guide in the head is critical to stop it moving and heat transfer between guide and head.  With knurling there is no control over diameter, particularly with formed rather than a cut knurling.  This will most likely mean that it will be over size on the O/D and cause further damage to the bore of the hole in the head, that is to say the knurled guide will "machine" its way in (even with the head hot), completely ruining the hole.  The inevitable consequence will be a guide not held as tight as it should be and oil will weep down the O/D of the guide.

The only way to sort this is firstly check the hole is round and parallel, if it is make an over-sized guide. If not bore the hole round and parallel etc. 

Loctite is not a great idea as it may well form a thermal barrier between head and barrel.

OP, the offers there to do the job properly!

I notice that the Club offer Phosphor Bronze guides, its not the best material for guides, Cast Iron or Aluminium Bronze (Closibro) are much better.

I’m sure I have some spare heads somewhere! 

I think the guide valve guide internal diameter is 7.12mm or 0.280 inches approximately 9/32". This was measured using a cheap digital vernier caliper so it may not be accurate enough for you.

The manual states 0.2827" as the "bore size" for the inlet and exhaust valve guide. And 0.2795/0.2787 for the valve stem diameter.

Dennis

Jonathan,

I have sent you a personal message through NOC.

Dennis