Keeping in mind that I know NOTHING about post-1975 Volvos (I probably can't even drive one), The grade of gas can be suspect. I only run 92 or better (when I can find it). If I put in anything less, it pings like crazy when going up hills, etc. I also noticed that if I set the timing too far clockwise (is that retarded or advanced? Am I retarded or...) it will ping/knock. So it might just be the timing. I'd like to hear other peoples' opinions on it, though, as some mechanics say it doesn't matter what kind of gas you use and if it runs better with higher octane it's indicative of another problem. Contrary to popular belief (and I'm probably getting over my head here; we'll see if anyone notices), higher octane doesn't necessarily burn HOTTER, but it has something to do with the point at which the fuel combusts on the piston's stroke, so perhaps changing the timing is all it takes. I supose I should ask "What kind of knocking are you experiencing?" [the quotes indicate my saying that phrase aloud causing the cat to look around for whom I'm addressing] If it's that pinging you hear upon acceleration or hill climbing it's probably the aforementioned. If it's more of a tapping, it might be the valves in need of adjustment. If it's a mechanical clanking which occurs at all speeds, it might be something more sinister as alluded to in a previous post. Once I traced it to a bunch of washers in my ashtray.

Good luck!

Ben
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