G3L head bolt Torque setting

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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bunners
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G3L head bolt Torque setting

Post by bunners »

Morning all
I have looked it my manual for the torque setting for my G3L but cant find any settings at all, can someone please advise?

Cheers
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Re: G3L head bolt Torque setting

Post by SPRIDDLER »

On the recommendation of ex AMC dealer Ken Bryant ('ITMA' on the forums) I've always tightened my '54 G3lS head bolts to 30 ft/lb which saves retightening later. Always anneal the copper gasket, even it's a new one. I'm sure you're familiar with doing that but just for the record......
Heat to cherry red. For some reason the gas flame and cherry red doesn't show in the photo. (My gas cooker ring is the perfect size):
Head gasket heating in pliers (640x427).jpg
Then drop into cold water which will throw off any contamination:
Head gasket cooling (640x480).jpg
Rocker bolts to 10 ft/lb. after ensuring that blind holes in the cyl head aren't full of crud (old gasket material etc.) or the bolts will tighten to 10 ft/lb but the gasket won't be sufficiently compressed and you'll get an oil leak. Owners have tried to stop the leak by tightening the bolts even more............and stripped the thread in the cyl head.
LATER EDIT - Ah, it has just occurred to me that a G3L will probably have an iron head which is less likely to suffer stripped rocker bolt threads.

Useful article by Ken with data and some settings here:

http://archives.jampot.dk/technical/Spe ... hanics.pdf
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clive
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Re: G3L head bolt Torque setting

Post by clive »

torque setting is medium spanner.
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Re: G3L head bolt Torque setting

Post by Mick D »

Hi

You'll get a better heat distribution if you suspend the gasket with a bit of thin wire rather than self grip plies ;)

Regards Mick
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Re: G3L head bolt Torque setting

Post by SPRIDDLER »

Mick D wrote: Fri Aug 13, 2021 4:45 pm Hi

You'll get a better heat distribution if you suspend the gasket with a bit of thin wire rather than self grip plies ;)

Regards Mick
Good point, Mick. I normally anneal twice, holding it in two different places.
It's a photo I mocked up (back in 2009 apparently) in response to a forum question about annealing.

No A** assessment for my course work then. :(
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clive
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Re: G3L head bolt Torque setting

Post by clive »

A* for the pretty plate though
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Re: G3L head bolt Torque setting

Post by SPRIDDLER »

clive wrote: Fri Aug 13, 2021 9:11 pm A* for the pretty plate though

I use far better decorated ones in the camper for annealing chums at biking rallies.

CIMG4517 (640x480).jpg
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Re: G3L head bolt Torque setting

Post by 56G80S »

Having seen the damage from overtightening by PO and myself in my youth, I would definitely ensure that you find the largest O/D washer that will fit without fouling the rocker box and ensure it is sufficiently thick.

Well worth ensuring that the bores in the cylinder head that the head bolts pass through are not damaged and allow the bolts to pass through and rotate freely.

Sprid, it's a 1957 G3L - IKBA about the 350's but wouldn't that have an alloy head by then? If I'm wrong then the advice above is crap.

Johnny B
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Re: G3L head bolt Torque setting

Post by SPRIDDLER »

56G80S wrote: Thu Aug 19, 2021 8:54 pm Sprid, it's a 1957 G3L - IKBA about the 350's but wouldn't that have an alloy head by then? If I'm wrong then the advice above is crap.

Johnny B
Indeed so, John. I was put off the scent by Bunners having written that it was a 'G3L' without mentioning the year.
bunners wrote: Fri Aug 13, 2021 12:04 pm I have looked it my manual for the torque setting for my G3L but cant find any settings at all, can someone please advise?

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