My 86 IROC has a what seems to be a bone stock lg4. I get some spark knock when I use regular. Not real bad ping, just when I excelerate I get a rdddddd, or something like that.

None of these cars require anything more than regular from the factory.
If you're getting knock then you have a different problem.

check your timing

Timing is too far advanced.possibly. i use premium 93 in all my vehicles ONLY!!

Why do you only use 93? I would think I would get better performance out of my tbi w/93 since I have a spark knock sensor.. the lack of knock, the more the timing should stay advanced.. Do you know if this is the case?

Check your EGR valve. It isn't uncommon for the exhaust passages of the EGR circuit to get plugged, which will give you pinging under light acceleration.

But check the timing as well. Unless it's been moved, though, that shouldn't change.

I only use 93 because my car seems to perform better. Thats a matter of preference. Some people have better luck with 87 octane. Most manufactures reccommend 87. Although i had a 94 Cadillac eldorado and the book said to use ONLY Premium 93 octane in its Northstar v8. I would check the things that 57kid said as well. Also if your knock sensor has not been changed i would change it anyway. every little bit helps. good Luck

Also remember if you check your timing make sure you unplug the wire that goes to the distributer before you set your timing. Then plug it back in afterwards after timing is set.