LT4 idle question

How much timing changes should i expect to see when logging timing for idle?

My commanded RPM is 850 after my Cam, Mag2650, NW 103tb, Big Gulp install in 17 ZL1. I see my RPM fluctuate 740-870 range and timing from appx 7 to 20 degrees. Some times when i am at a stop i feel the car shake as timing fluxs. Been trying to figure out a good fix for this. The original Tuner did adjust the Idle Torque tables by slightly bringing down the reserve and external load tables. From what i find on the net searching, some say add timing to the Base min spark table, some say remove TQ from the VTT. Others say add to the idle reserve table, others say remove. I feel like i am going in circles.

So, first question, what is a normal amount of timing fluctuation is to be expected? 5 degrees? 10 degrees?, 2 degrees? I have no idea!!
Being that i am already at positive timing, which table should i concentrate on ? MAF is already dialed in to appx 3% or less.

Any help would be great!

Timing is going to jump around especially on a cammed car. I would worry to much there as long as you're in the positive. I would start with the external load. We usually add around 50 to the warmed up value and blend it a bit but you might need to experiment a bit. If that doesn't work you can lower the VTT in the idle area but we usually only need to do that when timing negative.

Thanks for the info. Guess for me is what makes it so confusing for the load table is that some say lower the numbers for adding a big cam and others say raise for supercharger.. And I have both.. I tried messing with the vtt by lowering it in my area of concern with no luck.

My load table numbers are lower than stock by the original tuner in the range Im dealing with. You said you go up, so you go up with cam and bigger sc?

You don't want to add to the minimum timing tables. This will make the vehicle surge more than likely. If you are going too high over the rpm when you're under, then change your proportional idle table to add a little less air to not overshoot the intended airflow. Same goes for how much is removed. If you have a big swing, increasing the first two +/- inputs can help before it gets too much out and hits the higher flow numbers. I can idle a LT engine within 20rpm and bouncing the spark advance up/down with a huge cam looking to eat it's next opponent. Bump that external load up a good amount as well which was stated already.

thanks for the reply...what is the proportional idle table for Gen V engines you mention? An example of what i am dealing with is in this log i did the other day while MAF logging. You will see some idle numbers drop into low 700s while my commanded is 850. The timing is swinging up and down.

Anyone?