Read that the 85 ECM is ****ty because it has a SLOW bit transfer, looking at the chart I decided I do NOT want a 90-92, but I want the easiest year to tune, would an 88 or 89 be suffient? There are slight differences according to the chart with all ecms but I don't exactly understand how they are different and why the require different chip sets.

 

1985-----------870 ECM---MAF
1986-1989----165 ECM---MAF
1990-1992----730 ECM---MAP (speed density)

Now, with that out of the way...you have a 305 in your 85 still?
If so you'd just need to repin and splice your harness to accept the 165 ECM, then you'd need a calpack for a 305 from any of the years covered by the 165 ECM ($50-$75 from GM)
If you are swapping to a "built" engine you'd also need to get into prom burning...that's a horse of a different color.

 

For an 85 it's actually easier to switch to the SD '730 ECM. I know because I first switched to a '165 and then to the '730.

 

Current motor is a supercharged 350, I have heard froms omeone else to find a syclone ECM to adjust? What do I do here peeps? thank yoU!

 

Look here for the Syclone/Typhoon conversion. http://www.speedtoys.com/~bort62/7749/Index.htm