The factory settings were generally a bit on the conservative side, as they were trying to get the best compromise between power and fuel mileage and the gas was pretty good compared to todays gas. If your factory setting is 6 degrees, you could probably get away with as much as 10 degrees of advance. If, on the other hand, you are talking about a performance application, to get the best out of it, there are other people here that are more qualified than me to help you.
Maryland Chevelle Club #017
progress has little to do with speed, but lots to do with direction. Maryland Chevelle Club
The ideal TOTAL timing for a small block Chevy (will vary depending on heads/cam/compression ratio....) is generally recognized as around 36 degrees btdc. Total timing is initial (base) + centrifugal. Generally if you have a performance engine you will want to be "all in" by 3,000 rpm.
The only way to verify if 36 degrees is ideal for YOUR combo would be careful testing either at the dyno or at the track. If you can't run that much ignition advance due to spark knock (sounds like marbles in a coffee can), there is a good chance that you are running a fuel with too low of an octane rating, or are running too lean.
Another thing to consider when discussing timing is part throttle timing which is controlled by vacuum advance. This is very important because it helps keep your part throttle fuel mileage decent and helps keep your engine cool. One way to check if you are in the ballpark if you have a stock engine is to compare how much vacuum advance you get at a given vacuum reading -vs- the specs in the Chevrolet shop manuals.
[This message has been edited by Unclepennybags (edited 01-21-2002).]
From all the dyno tests I have seen 36deg by 3000rpm is usually best. The vortec's and fastburn heads like 34 a little more. Either way this should be a good starting point.
Another thing, is your never going to be able to set it if you don't know what it is. Make sure you have the right timming mark, pointer combo. I would also be nice if you could make sure it says TDC when it is TDC.
My stock 307 likes 32 total best. Increase timing until you get detonation (pinging) and then back it off a degree or two. Should be your best setting for power/gas mileage. Well, it's been best for mine.
Better Late than Never Fred
Team Chevelle #400
I'd rather have a bottle in front of me, than a frontal lobotomy. 1970 Chevelle Malibu
I've got KB Claimer pistons in my 383 and the KB web site has info and recomendations for each piston they sell. They recomend 34degs for their 383 pistons. The Claimers (Hyperutetic sp?) series they say run best with a deg or 2 less timing.
I'm sure quench height, valve - size, lift and duration as well as head chamber size all come into play. Recomendations are a good place to start...
In a performance engine you want your timing to be all in when your engine starts making the most power. For driveability on the street you want a curve where as a dragster may actually run a fixed amount of advance as it's all or nothing at the gas pedal. That's why the posts above all say "all in before 3000rpm".
You might consider getting a "Timing Tape" which you glue to your harmonic balancer. They make "dynamic" timing much easier. It is a snap to set total timing at RPM with one and they only cost a few bux.
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