i have a vortec 350 with voodoo 262 cam, 9.6 compression, rpm air gap manifold and 600 edelbrock carb. right now it has about 10 degrees initial timing and i have the vacum advance screwed all the way. the problem is i have it idleing at 800 rpm and when i put it into gear i almost wants to die out. could i bump the timing up to around 14 without detination? i run 93 octane all the time.

 

I've got a combination similar to yours ( less cam with more static compression). I'm running 16 degrees initial however I've limited the total mechanical advance to 18 degrees for a total of 34 (not including vacuum advance). I use 94 octane and no issues with detonation. Last road trip yielded 23 mp(canadian)g highway too.

 

how do you limit the mechanical advance? iv read that the stock hei gives about 20 degrees mechanical so bumping up to 14 would put me at 34 total too.

 

Stock HEI's and aftermarket pieces can have 20 to 22 degrees total mechanical. Some aftermarket units have adjustable mechanical limits. In the stock case, the length of the slot which allows the advance needs to modified to decrease the total advance. Check out this article: http://www.chevyhiperformance.com/ho...438/index.html
In my case using a distributor machine, it was determined that the first 3 degrees of advance would occur below 500rpm. Essentially this meant with the engine at idle, those first 3 degrees didn't impact the timing the motor would see under operating conditions ( why this happens in this particular Mallory distributor I can't say ). What it did mean was that there was only 18 degrees of mechanical advance available which turned out to be ideal.
Keep in mind that the rate at which the advance comes in and finishes is also important. All in by 3000rpm is pretty much a standard.