Ignition timing.
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Ignition timing.
Hi all, should my 1961 Matchless G3 be 1/2" btdc or should it be 7/16"btdc (@ full advance) as I have read both?? Confused, Ian.
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Re: Ignition timing.
Hi Ian... I'm sure that many more knowledgeable than I can add more, but my understanding is that the 'official' AMC spec is for 1/2" BTDC, but 7/16" is considered more suitable for the characteristics of today's fuels.....
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Re: Ignition timing.
Thanks for the reply Colin, as I've got the head off I thought that I would get it spot on just not sure which spot, best regards, Ian.
- Duncan
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Re: Ignition timing.
Hi Ian, the book timing changed at engine number 41575 from 1/2" (39 degrees) to 11/32" (34 degrees) I believe this corresponds with the introduction of the short stroke engine.
Most coil ignition automatic advance/retard units will have some wear in them so I would advise against using the retarded figures quoted and always set at the maximum advance.
Most coil ignition automatic advance/retard units will have some wear in them so I would advise against using the retarded figures quoted and always set at the maximum advance.
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Re: Ignition timing.
Hi Duncan & thanks for the reply, this is from Ken Bryant
on servicing the heavyweight singles, and that's what was confusing me?? Kind regards, Ian.
on servicing the heavyweight singles, and that's what was confusing me?? Kind regards, Ian.
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- Duncan
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Re: Ignition timing.
Interesting Ken knows his stuff, As you have the head off I would mark the back plate for both 1/2" and 7/16" with permanent marker or paint so that you can decide which one suits your engine best when back together, its a work of moments to loosen the back plate and rotate a little, 1/16" is probably in the margin of error for the stick down the plug hole method. I find B8's a bit cold for normal riding.
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Re: Ignition timing.
Don't get paranoid about it. Considering wear and backlash I'm happy to end up with anything between 7/16" and 1/2" on my road-going, softly tuned and long stroke plonkers.
As Duncan said and as far as I'm concerned, setting the timing with a stick down the plug 'ole and a fag paper to within plus or minus 1/16" takes several attempts and is a target rather than an absolute commitment - rather like a politician's manifesto promise.
As Duncan said and as far as I'm concerned, setting the timing with a stick down the plug 'ole and a fag paper to within plus or minus 1/16" takes several attempts and is a target rather than an absolute commitment - rather like a politician's manifesto promise.
'There is a tide in the affairs of men
Which taken at the flood............'
Which taken at the flood............'
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Re: Ignition timing.
Thank.you for the reply, marking the backplate seems a good idea as the head is still off, many thanks, Ian.
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