barnym17 wrote:Sometimes it is the light, also it is common with many electronic ignitions to see retard as rpm goes up.Its called slew rate or something like that.Basically it takes the electrnics a set amount of time to trigger the spark and as rpm goes up it falls behind.Many can be 1 or more degrees per 1000 rpm.
CREngines wrote:Which box are you using? The new digital 6al produces an immediate 4 degrees retard over the older boxes just swapping it out and a gradual two to three degrees with rpm. Just went through this with msd over a brand new box for the dyno. They are replacing it right now with a 6ALN (old 6al) because if i send a motor out the door with the ignition set off of the new digital box and it is installed in a vehicle with the old box the timing will advance 4 degrees. Needless to say that is bad for business. This is a noted problem with the new digital boxes from msd. they claim the old box loses 2deg at 10000, but this new stuff loses it alot faster. Also ensure that when the distributor was locked out the nut is tight so the reluctor ring carrier does not move independent of the shaft even a little bit.
I like my timing to stay where i set it.