Coil valve springs

Information relating to the Matchless G5 or AJS Model 8 350cc Lightweight
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Coil valve springs

Postby Martin.S » Mon Aug 13, 2018 10:10 pm

Can the G5s be converted to coil valve springs?

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Re: Coil valve springs

Postby Ozmadman » Mon Aug 13, 2018 11:50 pm

Martin.S wrote:Can the G5s be converted to coil valve springs?

You will need a coil spring head
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Re: Coil valve springs

Postby clanger9 » Tue Aug 14, 2018 7:09 am

Martin.S wrote:Can the G5s be converted to coil valve springs?

Apparently there was a conversion kit back in the day, so it can be done.

Steve at AMC Classic Spares has the necessary coils and spring caps, but not the collets. Probably best to give him a ring, as he has a few second-hand bits and might be able to confirm whether there is any material difference between the heads.
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Re: Coil valve springs

Postby Rob Harknett » Tue Aug 14, 2018 8:55 am

Why convert? If it is due to difficulty in getting hairpin springs, it may be just as difficult to get coil springs.

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Re: Coil valve springs

Postby Ozmadman » Tue Aug 14, 2018 1:44 pm

Rob Harknett wrote:Why convert? If it is due to difficulty in getting hairpin springs, it may be just as difficult to get coil springs.

clanger9 reckons Steve has springs, would be good to find out if conversion is possible as my hairpin springs have seen better days and the spare set I are not much better... keep us posted please
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Re: Coil valve springs

Postby ajscomboman » Tue Aug 14, 2018 3:02 pm

Ken De Groome carries out conversions from Hair spring to coil on the Heavyweights so I don't see why he wouldn't be able to help out on the Lightweights.

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Re: Coil valve springs

Postby Martin.S » Tue Aug 14, 2018 5:02 pm

I called Steve at AMC Classic Spares - nice chap - who spent some time with me talking about the later coil spring fitment on the lightweight CSR's.
He said that he has the dual springs and spring caps but not the bottom spring seat and collets. The valves are the same ones as the later model but the collets are a different part No. The spring seats are similar to the Gold Star type(looks like a plain washer).
He said that the heads are the same so I will be investigating the collets when I can find a little extra cash (not that they're that expensive) but I've got other things to buy.
Steve - if there's a mad rush to buy these then put me a set aside!
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Re: Coil valve springs

Postby clanger9 » Tue Aug 14, 2018 5:09 pm

Ah yes, I forgot about the spring seats. You can use Triumph Tiger Cub collets on the exhaust valve.
The inlet valve collets are a real problem: no-one seems to have any! It's an unusual stem size (9/32").

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Re: Coil valve springs

Postby Martin.S » Wed Aug 15, 2018 9:40 am

Nice blog - thanks Clanger.
I've been thinking - how about tack welding the oversize collets to an old valve thus holding them to to enable the taper to be turned on a lathe to the right size? - or perhaps just turn up some new ones - I've got a lathe! - anybody know of any snags in doing this?

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Re: Coil valve springs

Postby ajscomboman » Wed Aug 15, 2018 3:51 pm

Wouldn't be too hasty in rushing the conversion. I had reason to contact Ken on another matter today and happened to mention this thread and the conversion from hairspring to coil using the original factory setup. Wasn't something he'd recommend as they're very very close to becoming coil bound. His conversions use commando parts and titanium seats etc. Very nicely done as well having seen the work and had it done on my CS motors.

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