Milest

I am currently set up with 16 deg initial timing with to total advance of 37 in at 2500 RPM. Car runs great and it felt much more responsive after advancing over stock.

However, something keeps telling me that GM went to alot of trouble with stickers and manuals to suggest the 8 deg initial. What would be the reason for stripping a performance car of performance when it is so easy to change?

KenSny

Well, one reason was to keep the emissions police happy.

Gerry

That's exactly it. GM had to sacrifice a lot of performance to keep the cars within the federal smog rules. (Why do you think the late C3's only made ~190 HP) I can't remember which of the two bad gases it is, but advancing the timing at idle increases it.

I know several people who adjust their timing by retarding it back to spec just before going in for emissions testing, then after they pass, set it back the way they like it.

lars

The guys are right - the retarded spec is to lower emissions at the sacrifice of performance. Advancing the timing increases Hydrocarbons - retarding it drastically lowers hydrocarbons, and is an easy way to pass emissions requirements. This is also why they put very short centrifugal advance curves in the late-70's cars: keeping timing somewaht retarded at elevated rpm keeps cruise-level emissions down, too. And that's why it's so easy to get a noticable performance improvement by "fixing" the timing and timing advance systems in these cars.