[Diy_efi] ignition timing variation

[Bruce]

How are you detecting this jitter?.
If you're using a conventional *home grade* timing light, that might be a
characteristic of the timing light.  Some just don't trigger accurately.
Might consider mounting a second sensor done differently, and then compare
the two output signals, and see if the timing is really wandering around.
  If the timing error is constant, then why even worry?.   Just include that
in your timing table.    After all does it matter if the timing is a cal'c
34 d or actual 34d as long as the engine is making max HP?.
Bruce

----- Original Message -----
From: "Stewart Prince" <sprince at csun.edu>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, July 30, 2002 3:57 PM
Subject: [Diy_efi] ignition timing variation


> Does anyone have any information on "acceptable" variation of ignition
> timing?  We're getting about +/- 2 degrees of jitter on our home-built
> EFI system (Formula SAE).  By my calcs, 100 microseconds of error
> corresponds to 1.8 degrees of rotation at 3000 rpm, and 7.2 at 12,000
> rpm (assume constant angular velocity). I believe the students are using
> the time between the last two teeth on an 8-tooth wheel (crank mounted)
> to calculate engine speed.  Is it possible that some sort of averaging
> scheme should be used to account for the speed variation due to
combustion?
>
> --
> STEWART PRINCE



_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi