Norton Jubilee Valve Guide Drift

Previously dennis_thompson wrote:

Does anyone know where I can buy a valve guide drift for a Jubilee? The valve guides are a nominal 7mm bore and most other British bikes are 8mm (5/16"). I have already bent one new valve guide when a cheap drift punch broke on me.

VW Golf use a 7mm guide but their drift is £20 and I don't know if it has a square shoulder.

Many thanks,

Dennis

Hi Dennis, ready to be shot down here, assuming the drift is to drive the old guide out..but a good friend of mine advised me to tap the top off the valve guide with a hammer - sharp tap, to break it off, then drift the guide through from the top. This means that any carbon build up on the exhaust / inlet side does not drag through the cylinder head with the accompanying damage. Given the head was "warmed" to about 120 C (I think but check...) pre drifting the guide down, I was very happy with the results. The tops broke off very cleanly - Iron, and I had clean guide bores ready for the new ones.

If you are trying to drift the new guides in, are they iron or bronze?

One other thing though, do you really need to replace them, it might be better to sleeve them as you will need a specialist puller to pull the new guides in (even when the head is hot) and from my experience this is a fraught process. On top of that there will be a secondary process of valve seat cutting before you can install new valves, depending on how well the valve guides were pulled in, this may produce an offset valve seat. I suggest you get more advice or find a friend with a lathe.

I can send you my drift but it is only part of the solution. Learning journey etc....

Andrew

Does anyone know where I can buy a valve guide drift for a Jubilee? The valve guides are a nominal 7mm bore and most other British bikes are 8mm (5/16"). I have already bent one new valve guide when a cheap drift punch broke on me.

VW Golf use a 7mm guide but their drift is £20 and I don't know if it has a square shoulder.

Many thanks,

Dennis

Previously anna jeannette Dixon wrote:

Previously dennis_thompson wrote:

Does anyone know where I can buy a valve guide drift for a Jubilee? The valve guides are a nominal 7mm bore and most other British bikes are 8mm (5/16"). I have already bent one new valve guide when a cheap drift punch broke on me.

VW Golf use a 7mm guide but their drift is £20 and I don't know if it has a square shoulder.

Many thanks,

Dennis

Hello when knocking out any valve guide you need to put your cylinder head in the oven on full for a good half hour then you will need a good size block of wood to drop the cylinder head onto the valveguides shoulddrop out by now a good solid bass 5/16th rod will knockthem out, you Never Kock valve guides out Cold, and replace them you need to pre-heat the cylinder head in the same way and buy your self a good pair of welding gloves you need them, yours Anna J

Quite agree Anna, I had not made that plane. Even heated for half hour I needed a drift to get them out. To get them in, I used a tool like the attached to pull a new one in, but again the head has to be heat soaked. The guide was then reamed / honed, then seats re-cut.

https://normanhyde.co.uk/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/G/A/GAS12_5.jpg

Andrew

Previously dennis_thompson wrote:

Thanks for all the replies. I am trying to fit new bronze guides. I followed the instructions in the re-build guide to drift out the old iron guides and they came out easily. They were worn out where they rub against the valve stem but they are a good interference fit in the head. The new guides are bronze, not iron. The new guides will go back with the head heated as I did one successfully before the punch broke. Unfortunately, the bore on the guides is 7mm not 8mm (5/16) like larger twins.

I should like to take up the offer of a drift from Andrew, provided it is no wider than 7mm.

My only problem is finding a drift; the technique is fine

Sorry Dennis, my drift is for removing - steel and flat shoulder. I also put bronze ones but needed the tool like the one in the picture I sent you. Borrowed mine of a mate. You need to watch for the top of the guide as that is the oil scraper - should be a knife edge and a drift would spoil that.