Author Topic: Ignition Conversion Chart  (Read 2966 times)

Offline Beezageezauk

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Ignition Conversion Chart
« on: 11.02. 2007 16:56 »
Hello Erling.

I have on my PC an "Ignition Conversion Chart" in M/S Excel format.  This chart will allow you to add certain details of the engine and will automatically calculate the degrees required to set the Ignition Timing.

I was trying to help BSA59 with his "Timing" question but unfortunately, because this chart is not in JPG format I cannot transfer it to the forum for the benefit of the members.  Furthermore, I can't find a way of asking BSA59 to contact me offline so I could sent it to him by Email.

Is there any way that this is possible?  Maybe I could send this chart to you by email if you could post it on the forum?  I feel that it would be better to have it posted for all to see.  The other problem is whether the formula in M/S Excel will work under these conditions!!  Is it worth a try?

Beezageezauk.

Offline a10gf

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Re: Ignition Conversion Chart
« Reply #1 on: 17.02. 2007 12:57 »
Here it is for download. Give us some feedback how it all works.

http://www.a7a10.net/BSA/ignition%20timing%20converter.xls

A10 GF '53 My A10 website
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Offline dpaddock

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Re: Ignition Conversion Chart
« Reply #2 on: 20.02. 2007 22:25 »
Nice work, guys! This should help Fred and a whole lot more of us.
David
'57 Spitfire


Offline dpaddock

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Re: Ignition Conversion Chart
« Reply #3 on: 20.02. 2007 22:43 »
Hold on! The stroke listed on the chart is for 65.2 mm; 84 mm is the A7/A10 stroke.  A10gf might want to check that the values given are correct for 84 mm.
David
'57 Spitfire


Offline a10gf

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Re: Ignition Conversion Chart
« Reply #4 on: 20.02. 2007 23:09 »
HI, to Beezageezauk, can you provide the info on how to best use the chart, insert the correct values etc ?

Thanks
E.

A10 GF '53 My A10 website
"Success only gets you a ticket to a much more difficult task"

Offline Beezageezauk

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Re: Ignition Conversion Chart
« Reply #5 on: 21.02. 2007 20:12 »
OK, here are the instructions on how to use the Ignition Timing Conversion Chart.  First of all you must remember that all the information is in inches.

The chart is produced in M/S Excel format and it contains hidden formula.  This allows you to change certain data for different engines and the chart will automatically calculate the distance before top dead centre at all the degree readings.

At the top of the chart the Rod Length reads 6.000 and as the A10 rod length between the centre of the big end bearing and the centre of the little end bearing is 6.469inches, change the 6.000 to 6.469.

Next the Stroke reads 2.568 and the A10 stroke is 3.307inches so again, change the 2.568 to 3.307.

Please note that these figures ar for the A10.  The A7 conrod length is 6.000 and the stroke is 2.858.

Every time you change one of these figures and move the curser to another cell all the figures under the word Linear will change automatically.  These figures are the distances in inches BTDC compared to the degrees that are listed to the left of the Linear measurements.  These, of course, range from 0 to 179 throughout the chart.

To help convert these distances in decimal inches to fractions, here are the more common measurements given for A7 and A10 machine ignition timing.

5/16 = 0.3125"      11/32 = 0.344"     3/8 = 0.375"     13/32 = 0.406"

So if your bike should be timed at 5/16btdc, add the relevant dimensions for rod length and stroke then read the chart where it says 0.3125 (or nearest) and whatever number is to the left of this figure is the equivalent number of degrees btdc.

I hope that I've managed to explain it OK.   *whistle*

Beezageezauk.




Offline dpaddock

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Re: Ignition Conversion Chart
« Reply #6 on: 01.03. 2007 17:59 »
My apologies, Beezageezauk; I didn't read the instructions.
Good work! *red*
David
'57 Spitfire


Offline BrianDallasTX

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Re: Ignition Conversion Chart
« Reply #7 on: 03.03. 2007 04:10 »
geeza-  Thanks this is a great resource.  Very simple formula for Xcel and the applications are boundless.  thanks again.
Brian
'63 A10 Super Rocket

Offline muskrat

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Re: Ignition Conversion Chart
« Reply #8 on: 13.11. 2013 11:50 »
Marvelous what you find with search. I couldn't find my old calcs to covert. I needed to check a mates A7, cam ring a bit out 33 and 37 so either side of the required 35. Don't think it will hurt, he never exceeds 50mph.
For those without Excel, here they are.
Cheers
'51 A7 plunger, '57 A7SS now A10CR, '76 XT500, '77 AG175 '83 CB1100F, '81 CB900F project.
Australia
Muskys Plunger A7

Offline morris

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Re: Ignition Conversion Chart
« Reply #9 on: 13.11. 2013 20:30 »
For those who don't have MS office, it also works with Open Office Calc. This can be freely downloaded on www.openoffice.org.
It also contains a PDF converter. Found it often very handy
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