I tried to search for this on here, but couldn't find it. Somewhere a while back I saw a timing recommendation for the 1st gen V6 ('87 in my case) if you were having problems with knock at the factory setting. I am having problems with it, but now I don't remember what the suggestion was (and, TBH, I don't remember offhand what the factory setting was, but that is what I set it to last time I fiddled with it). Anybody know?

 

10* BTDC is recommended; if it's knocking, you probably have some carbon buildup. I would NOT pull any more off (shucks, I'm about to run mine up to 14* to 16* BTDC.)

Try upgrading to 89 octane.

And then, consider doing a upper cylinder clean. I'm so I use Berryman B-12 Chemtool; Seafoam is also popular.

RwP

 

I've gone to 89 and am still having some problems, I'll try Seafoam and see if it helps. I'll also check and make sure the timing hasn't wandered since I set it.

 

Seafoam and try some 93 octane in it.

Are you positive it's preignition and not something like a rod knock?

How old are the spark plugs? Might not hurt to put new ones in (copper ideally!) and read the old ones when they come out.

RwP