Comet Valve Lifter

Ian Scott

Active Forum User
Non-VOC Member
I have to get access to establish what has gone wrong with the valve lifter, it feels like the return spring has broken or come adrift. The valve lifting action never felt immediate and seemed to be delayed, now the operating lever does not self return. I've only had the bike a few weeks and am recently a new club member. I need technical information on what has to be removed from the timing cover prior to removing the cover itself. I have not found any detailed information or detailed drawings that would assist. Perhaps an experienced Comet owner might be able to assist me by pointing me in the right direction?
The year of the machine is 1951.
Many thanks.
 

timetraveller

Well Known and Active Forum User
VOC Member
Hello Ian. Welcome to the wonderful world of Vincents. You should buy or borrow a book by Paul Richardson on Vincents and get a copy of the 'Spare Parts List' and look at drawing MO64. You will need to remove the banjo bolt at the front of the timing cover which interfaces with the oil filter housing, the 'big end quill' which is the hexagon headed brass item in line with the main shaft and the dome headed nut on top of the timing cover which allows you access to the screw behind it. You will then have to undo all the screws and remove the timing cover. If it has been fitted with a setting gasket cement then it might need an oblique blow with a rubber mallet to break the seal but there are two dowels behind the cover so go carefully. You can then see inside and might be able to see what has gone wrong. If it is not something that can be rectified without further dismantling then you will have to start to remove the insides. My advice would be to remove the push rods before starting to dismantle and try to ensure that the engine does not rotate otherwise you will have to re-time the valves and ignition. A dab of paint or marker pen on the pinions before you start to dismantle will help you to put things back where they were if you get a slight rotation of the pinions. It could just be that a small roller in the top of the lever which lifts the valve follower has fallen out and if so you should first of all make sure that you find it and remove it and then get someone to weld up the groove which contained this roller with a hard filler such as Stellite. There are Club members near to you who are very experienced and might be able to help. Good luck.
 

chankly bore

Well Known and Active Forum User
Non-VOC Member
Well, you don't need to remove the big-end quill unless you are curious about it. It is a fine (26 t.p.i.) thread into alloy and is best tampered with infrequently!
 

Ian Scott

Active Forum User
Non-VOC Member
Many thanks Timetraveller and chankley bore, I've found a drawing on the web-site which is helpful but you can't beat the detail that you have provided having no doubt been down this road before, it saves me from falling into a trap. I served my time as a motor mechanic many years ago but I'm happy to ask for advice when I don't know the animal!
Thanks again. (I see I'm ID'd as a non-member???)
 

bmetcalf

Well Known and Active Forum User
VOC Member
See message #14 here http://www.vincentownersclub.co.uk/showthread.php?2525-Thinking-about-a-1952-Black-Shadow/page2
for book recommendations. There may be more recommendations following. There is a lot of information available and some reading would benefit your efforts.

Regarding leaving the quill in the cover, they can be delicate and you would need to pull absolutely straight out on the cover. Removing the broken off end from the crankshaft can be quite a challenge.
 

Albervin

Well Known and Active Forum User
VOC Member
It take a little time for the pigeon to get the message from the membership secretary to the webmaster. Don't fret. I take it you found all the drawings on the VOC site. Also check out whitakerpedia for some more insight.
As has been said many times,"Ask 100 people a question about Vincents & you will get 120 answers, all of which will probably be correct." If it isn't in a book then it will be on the internet somewhere.
 

timetraveller

Well Known and Active Forum User
VOC Member
Sorry Chankly but I am with Bruce on this. I know, and you know, that one does not HAVE to remove the big end quill but if you have never done it before and do not realise how careful one has to be removing the timing cover if the quill is left in place then one is likely to end up with a bent or broken quill. Better for new boy Ian to remove it until he sees how it works.
 

Ian Scott

Active Forum User
Non-VOC Member
Hi Albervin,
thanks for the information, you are absolutely right, the response is brilliant. Some other clubs need to take notice, unless their members don't know their machines.
I've looked at the drawings on the site, but you can't beat feed back from experienced club members.
Again, many thanks,
Ian
 

Ian Scott

Active Forum User
Non-VOC Member
Hi Bruce,
thanks for the advice, I'm going to have to take it easy from what you and others have said about the quill. I'm not faced with a deadline or under pressure which means I can "swot up" before I venture forth. It would be nice to see this removal on video!! I have had to tiptoe when stripping down an unknown piece of machinery before now, so hopefully I won't screw up. One member has kindly offered to give me a hand which I might accept if I chicken out.
Many thanks Bruce and thanks to everyone else.
 
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