Author Topic: A7 ignition timing  (Read 238 times)

Online Ratchet Richard

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A7 ignition timing
« on: 05.03. 2021 16:22 »
Hi all
In the process of rebuilding my 1958 A7.  I still have the cylinder head off and am trying to set the ignition timing.   I see that the points should open at 5/16” which I think is about 32o btdc fully advanced.
My question is around the pistons which hopefully I have attached a photo of.  I think the pistons are a higher compression ratio than standard, would this alter the ignition timing?
Thanks

Offline muskrat

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Re: A7 ignition timing
« Reply #1 on: 05.03. 2021 19:40 »
G'day Richard.
With higher compression you need to retard the timing a tad. In your case the pistons look like 7.5 or 8:1 which isn't a big increase so I'd stay with 32. Also depends on the octane of the fuel and fuel/air ratio. High octane = advance. Rich or lean mixture = advance.
If it pings under load retard the timing 1 degree.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online Ratchet Richard

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Re: A7 ignition timing
« Reply #2 on: 11.03. 2021 17:28 »
Thanks for the reply muskrat, very helpful. I am having fun with this old A7, learning something knew all the time.  Regards Richard