Castellated exhaust nuts
Re: Castellated exhaust nuts
Heat is the answer, use a small blowlamp for a few minutes and youll free it up.
Re: Castellated exhaust nuts
Heating might help but you need to get the head around the port area really hot. The alloy will expand more than the nut. Though as the nuts are brass? the differential expansion effect may not be as much as with steel. As chirpy999 says use a blowlamp. Go very carefully though if you still have carbs attached and petrol vapour around. I doubt a hair dryer or hot air gun would get enough heat in to the head. The reverse strategy is to use one of the various freezing sprays on the nut, or even better use one after heating the head. Halfords do one if I remember correctly callled 'Shock & Unlock". I've never tried it myself as heat then a squirt of Plusgas usually works (beware Plusgas near naked flames though!).
Re: Castellated exhaust nuts
Yay!
The nut is off finally, I put a blowtorch to it, I'm not sure how much that helped at all as in the end I rummaged about in my dad's old shipwright toolbox and found some caulking tools that look like heavy blunt chisels and, putting a heavy leather glove around the inside of the nut to protect the alloy fins in case I slipped I proceeded to hammer it slowly out.
It looks like it may have threaded at some point but one of the previous owners must have just kept tightening it, I brushed out some of the soot and a quick squirt of oil and I cleaned the threads as much as I could.
I will need to come back to this but in the meantime I tried the other nut with its very clean threads on the front head and wound it in until it stuck a bit and then worked it back and forward for a bit, then wound it in a bit more and did the same. This has actually made a visible difference to the threads in the port and they are much clearer than before, whether it will cause me problems in the near future we'll need to wait and see but at least I can get on with the rest of the work and means I can now remove the engine from the frame.
The nut is off finally, I put a blowtorch to it, I'm not sure how much that helped at all as in the end I rummaged about in my dad's old shipwright toolbox and found some caulking tools that look like heavy blunt chisels and, putting a heavy leather glove around the inside of the nut to protect the alloy fins in case I slipped I proceeded to hammer it slowly out.
It looks like it may have threaded at some point but one of the previous owners must have just kept tightening it, I brushed out some of the soot and a quick squirt of oil and I cleaned the threads as much as I could.
I will need to come back to this but in the meantime I tried the other nut with its very clean threads on the front head and wound it in until it stuck a bit and then worked it back and forward for a bit, then wound it in a bit more and did the same. This has actually made a visible difference to the threads in the port and they are much clearer than before, whether it will cause me problems in the near future we'll need to wait and see but at least I can get on with the rest of the work and means I can now remove the engine from the frame.
"The problem with quotes on the Internet is that you can't tell whether or not they're genuine" - Abraham Lincoln
Re: Castellated exhaust nuts
Ha! Today I have been swapping the front head for one off the spare motor with a usable exhaust port thread. Forgot that it was a very early example with the two piece metal intake stubs though. No problem I thought just get the short steel intake stub off the damaged head.
Heat (easy because the head was off the bike) followed by Shock & Freeze, followed by hammer and drift on one of the slots in the stub. Nada, except for starting to chew the stub.
Well, to be fair, it has been on for 30 years when I put the 28mm carbs on. What was someone saying about steel in to alloy? No need to disturb it usually and a bit of port smoothing and polishing may have made removal harder. New one ordered from NLM. It can stay in place if I bother to have the port reclaimed. Which won't be soon as I have another spare head if necessary.
Still, it brought back old times working on the delightfully simple and wonderfully modular Lambertini twin as I haven't even had a head off one for twenty years.
Heat (easy because the head was off the bike) followed by Shock & Freeze, followed by hammer and drift on one of the slots in the stub. Nada, except for starting to chew the stub.
Well, to be fair, it has been on for 30 years when I put the 28mm carbs on. What was someone saying about steel in to alloy? No need to disturb it usually and a bit of port smoothing and polishing may have made removal harder. New one ordered from NLM. It can stay in place if I bother to have the port reclaimed. Which won't be soon as I have another spare head if necessary.Still, it brought back old times working on the delightfully simple and wonderfully modular Lambertini twin as I haven't even had a head off one for twenty years.
Last edited by 72degrees on 11 Oct 2011 15:55, edited 1 time in total.
Re: Castellated exhaust nuts
"We're going to need a bigger hammer." A triumph for perseverance and the Brummagem Screwdriver. Well done!Monstyr wrote:Yay!
The nut is off finally, I put a blowtorch to it, I'm not sure how much that helped at all as in the end I rummaged about in my dad's old shipwright toolbox and found some caulking tools that look like heavy blunt chisels and, putting a heavy leather glove around the inside of the nut to protect the alloy fins in case I slipped I proceeded to hammer it slowly out.
Re: Castellated exhaust nuts
As an addendum to this, wheres the best place to get replacement nuts?
I'm currently looking at a set from here
http://www.morinispecial.it/joomla/inde ... Itemid=168
40 euros plus postage costs, are they available in this country, if so how much and where from?
I'm currently looking at a set from here
http://www.morinispecial.it/joomla/inde ... Itemid=168
40 euros plus postage costs, are they available in this country, if so how much and where from?
"The problem with quotes on the Internet is that you can't tell whether or not they're genuine" - Abraham Lincoln
Re: Castellated exhaust nuts
Apparently NLM do stainless versions but no idea how much. Let us know how many suppliers/prices you find.
Cheers.
Cheers.
Dave
Carpe diem .....
Carpe diem .....