Hairpin Valve Springs

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Andy E
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Location: Wiltshire, UK

Hairpin Valve Springs

Post by Andy E »

Hello

Last year I carried out a top end rebuild on my 1956 16MS (Converted to 500cc years ago). I replaced the hairpin valve springs with new items sourced from the club spares scheme. I did this due to wear where they sit under the valve collars.

I have removed the rocker cover so as to re-torque the head bolts and now see that all four of the new valve springs are contacting and marking the rocker cover at their highest point. The inlet valve rocker is also impacting one of the springs. None of this was happening with the original set of springs.

I see that the remedy for the rocker hitting the valve spring is to chamfer the lower sides of the rocker arm, and indeed this has already been done to the exhaust valve rocker. Are there any suggestions for dealing with springs contacting the rocker cover?
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1608
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Re: Hairpin Valve Springs

Post by 1608 »

From memory, this is caused by the springs deforming due to age and general lengthy use. If your springs have deformed already then they are probably of inferior quality as are most pattern replacement parts these days. As one spring sits inside its companion is it possible to change them over, it may help. The only alternative I can think of is to relieve the inside of the rocker cover.
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Rob Harknett
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Re: Hairpin Valve Springs

Post by Rob Harknett »

I never had this happen on my 350's and never paid much attention as to which way round I have fitted springs. I have however seen mention, they can be the wrong way round. So as stated may be worth trying as suggested. I have never had a 500. Does the bottom tray seat OK ?
Andy E
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Location: Wiltshire, UK

Re: Hairpin Valve Springs

Post by Andy E »

Thanks for the replies.

I did try to find out if there was a correct way to fit these springs, but I came across drawings and photo's showing them fitted both ways around. I'll try reversing them. The bottom trays are seated correctly, I had to machine out the central holes to fit around the later type valve guide spring clips. I must admit that I'm a bit anxious about removing material from the rocker box, but I have considered doing so. I also thought of fitting a second rocker cover gasket, but I'm not sure that that would make enough of a difference.

I have also noticed that the parts list shows a felt washer for the rocker shafts. Mine doesn't have these, where should they be fitted?
alanengineer
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Re: Hairpin Valve Springs

Post by alanengineer »

I found the valve springs would touch the head casting on my 1952 G3. I turned the spings around 180 degrees and it worked for me. Not a difficult job or one that takes too long.
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ajscomboman
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Re: Hairpin Valve Springs

Post by ajscomboman »

Andy E wrote:Thanks for the replies.

I did try to find out if there was a correct way to fit these springs, but I came across drawings and photo's showing them fitted both ways around. I'll try reversing them. The bottom trays are seated correctly, I had to machine out the central holes to fit around the later type valve guide spring clips. I must admit that I'm a bit anxious about removing material from the rocker box, but I have considered doing so. I also thought of fitting a second rocker cover gasket, but I'm not sure that that would make enough of a difference.

I have also noticed that the parts list shows a felt washer for the rocker shafts. Mine doesn't have these, where should they be fitted?
The felt washer fits into the rocker box before the rocker sleeve is fitted. They is a small relief for it to fit into but can still be a bugger to fit without the sleeve tearing it up. Many professional restorers of these engines don't fit them as they believe all they do is trap grime around the sleeve instead of simply letting filtered oil circulate freely. A couple of my CS motors don't have them and I can't say I've noticed anything detrimental happening to the sleeve or the rocker arm or the rockerbox itself.
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Rob Harknett
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Re: Hairpin Valve Springs

Post by Rob Harknett »

The felt seals do tend to stay wet, so may do some good should a bike be left standing for ages.
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