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28* advance at 2000 rpm sounds a little high. Maybe advance is coming in a little too fast. 28* at 2500 would be better, I think. (P.S. If your car can take that much advance and still not have any pre-ignition ping, then no problem. But, since you are having this problem, you should resolve it first, before final setting of advance rate anyway.)
Scott, I am one person you rarely have to worry about insulting!
That is a great question and although I can verify this on Wednesday, if memory serves me correctly, the timing stopped advancing somewhere between 2,000 and 3,000 RPM. Initially I had my wife rev the engine to 2,000 RPM and the total advance was around 28*, then I had her take it to 3,000 and it went maybe another 2*. After that every time I checked the total I was rev'ing it at the carb and regardless of how hard I pushed it she pegged around 30*......you're piquing my curiosity.
You are experiencing 18* of mechanical advance, normal mech adv is around 20-22* on a stock distributor, so you are in the ballpark. If you set your initial adv with vac adv unplugged at 16, your all in adv will be 34, which is fine. Then all you need to worry about is how much your vacuum adv adds. You can tell this by plugging the vacuum advance back in, and noting the difference.
Have you heard back from Lars yet? His paper is about how the Street Avengers are jetted way too lean, and have problems with stumble and hesitation as a result, it sounds like it's something you should read.
Hey Scott. Lars did get back to me (with his documentation) and says that the carb is running lean. Probably the case because I tinkered with the timing (setting at 16 per your post) yesterday and the issue remained. I then went to the lightest spring on the secondaries and while it still remained, it was better so I'm thinking that's probably where my issue lies....
This is just one of those bug-a-boos you run into where you have to continually say to yourself.... "I do this for fun, I do this for fun...I do this for FUN"
I'm going to order a jet set, will update as I get through this.