Well I decided to re-adjust my carb and timing today. On the timing, I plugged the vac advance line and setup my timing to 34degrees by 2500 RPM. This gave me around 26 degrees at idle. Seems high on the idle numbers to me?? Then when I plugged in the vac advance the idle timing jumped to 51-52 degrees. I am guessing that I must have the vac advance attached to the wrong carb vac line? 

Here are my impressions:
- The operation of your vacuum advance sounds fine.  That's what you'd expect it to d, i.e., you may have more than 34 degrees total at less than full throttle.
- I'm guessing you have the stock distributor.  They don't have nearly as much total centrifugal advance as a high performance unit, also NOT the MSD Street Fire, it is the same :-(   I think the one on my '81 had a max of 12 degrees.  So, if you use it and want to get a max of 34, your idle will probably have to be higher than desired, which could cause dieseling on shutdown.  Others will hopefully chime in on whether they think it is reasonable and/or easy to mod the stock distributor to get more centrifugal advance OR you may need a high performance distributor OR you may just find a compromise between best timing for WOT and idle.
- The springs in the stock distributor are VERY stiff.  If you are still running them, then the distributor is not fully advanced at 2500 RPM.  I suspect it would go several more degrees by the time you got to 5000 RPM.  That would be too much advance.  You need less stiff springs to get all centrifugal advance in by 2500, such as in the kits sold by Summit, Jegs, etc.  To set the total centrifugal advance, I remove the springs and let the advance open up all the way, even at idle.  Start-up and set timing to 34 - 36 degrees. Install the softer springs and verify that the full advance is in by around 2500.

BTW, I always loved the photo in your signature, so I got the same front license plate for my black '81.

Total advance is okay, but the distrubutor will need to be recurved a bit.  26 is too high at idle, and 50 is way too high anytime.  You may want to consider not using the vacuum advance when the mechanical advance comes in very quickly.  Or reduce the amount of vacuum advance when you increase the mechanical advance.

John, thanks for the compliment on the license plate. I have a Mallory Performance HEI distributor (although now I am learning it is their economical priced version,hummm). I also have the mid level springs installed. FLA VETTE2008-03-03 10:47:17

I found these one time while looking for something, They are great articals and tech files. "vetteclub.org/technicaltips/techfiles" sorry i'm not smart enough to make this a link maybe someone else can. I really liked the one about timing and ported or direct vacume. Hope these help.

Many performance distributors come with a mild stock advance curve, but are supplied with the parts to recurve the unit.  So the stuff is available if you do need to recurve.  And I suspect you will.

[QUOTE=bio11]

I found these one time while looking for something, They are great articals and tech files. "vetteclub.org/technicaltips/techfiles" sorry i'm not smart enough to make this a link maybe someone else can. I really liked the one about timing and ported or direct vacume. Hope these help.
[/QUOTE]

The address is no good...I've tried it several ways...

[QUOTE=bio11] I found these one time while looking for something, They are great articals and tech files. "vetteclub.org/technicaltips/techfiles" sorry i'm not smart enough to make this a link maybe someone else can. I really liked the one about timing and ported or direct vacume. Hope these help. [/QUOTE]

Sorry Joel, I said I,m not smart enough too do this, I can barely check my E-Mail.

Thanks Lonnie for the link, good stuff in there. Another good site I remembered is "Corvettefaq". In reading and thinking it is likely my mech adv was partially in when I measured since my idle was higher in park.