M3D ignition values - help!

[TorAtle]

Here's the first line from the ignition table in the .fig file:

40 30 22 6 12 20 30 40 40 50 50 50 50 70 80 90 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

 

I have interpolated those figures to match the 14 load sites and 400rpm increases which my GEMS uses.

 

Are they actual degrees?? I'm no expert but isn't it a bit early to ignite when the piston isn't even half way up the bore? GEMS only accept 0 to 60 degrees - probably for a reason

 

Also, just before the ignition table there's a section called 'startup timing'. This value is in my case 16. Is this the ignition advance at cranking speed?

 

Hopefully your are not all on easter holiday as I'm eager to fire up the car...

[TorAtle]

Found an old demo copy of M3D so I could load the file and compare.

 

Actual advance = Startup timing + (100 - .fig cell value)/2

 

Is this correct??

[Ian Macquarie]

I don't think so.

I thought all the figures in the advance section of the .fig file were double the actual advance.

The start up value is only for start up and does not affect the advance when running.

In your example I would expect cranking advance to be 8 deg and the running advance to be 20 15 11 3 6 10 15 20 ......50

That may look a bit odd but I suspect the 3 and 6 are an attempt to achieve idle.

 

Ian

[oilyhands]

The values are in half degrees, very early versions of the software (.map files) held the figures as the offset in half degrees from 66 degrees BTDC since the distributor trigger would fire at that point so a figure of 132 would be..

 

66 - (132/2) = 0

 

And 52 would be..

 

66 - (52/2) = 40 degrees

 

Now however its simply double the advance value.

 

Oily

[TorAtle]

Oily,

 

Well then I have the old version of M3d, and when I loaded in a new .fig file I get exactly the same...except the formula I mentioned earlier is dead wrong. The number 52 as in your example would be...

 

16 + (100 - 52)/2 = 40

 

Isn't that strange.

 

Anyway all is well at the moment, the ignition map is converted and loaded and tomorrow we'll see if the car starts or not.

 

Thanks.