I am setting mine at 12 BTDC and working with it from there.The factory specs of 4 or 6 BTDC are not enough.

  

What is your timing when at idle without the vacuum on?

1957 Thunderbird

312

I'm pulling your chain Mark - any ideas I can adopt to make my outfit run the way I want - I use them....

Here is another good article - and the guy writing it is the real deal...

http://www.gofastnews.com/showthread.php/604-Distributor-Curve-Science-Simplified 

 
 Steve Metzger       Tucson, Arizona

Steve! If you ignore the fact that its GM the theory this guy puts forth  applies to all makes in part 1 anyway.Interesting that GM made all different advance units depending on application.I dont think I have ever heard Ted wound up.Theres a 1st time for everything. 

  

Too much GM junk in there don't you think?????

You guys are going to get Ted all jacked up over the "ported" vacuum again!!!!!

http://www.fordmuscle.com/archives/2000/03/timing/

 
 Steve Metzger       Tucson, Arizona

Thank you Mike!Its well worth reading I think.

  

Here is the link. Mike

http://www.hotrodders.com/forum/distributor-tuning-theory-part-1-a-59033.html

1956 Fairlane Victoria (ORREO)

 

Overlooking Beautiful Rimrock AZ

Hello Ted. I was reading an article about timing and carb adjustment.The author states that the vacuum advance should be at full advance with vacuum at 2in  less than the lowest engine vacuum reading which in most cases is idling in drive.If the engine vacuum reading for example is 14 in drive and the particular advance unit on the car does not get to fully vacuum advanced position until the reading is 18 the advance unit is in the midrange of advance and CAN cause timing to be unsteady at idle in drive.I dont know how to post a link to this article but if you do a search on the internet for "distributor timing and theory-part 1" it should take you to "hotrodder.com.Its a 2 part article and is one of the best I have found to explain timing and advance.If someone can post a link its well worth reading.Explains for one thing why you should be using non-ported(fulltime manifold vacuum).When I was checking the vacuum advance on mine at idle in drive it is only advancing about 3-5 with manifold vacuum applied.Should be at least 10+.I will get in there with an allen key and readjust it.

  

By the book, the idle speed in neutral should not change when the distributor vacuum advance line is disconnected when the engine is idling.  If it does change, two possibilities include the vacuum line is hooked up to a direct vacuum source or the carburetor primary side throttle blades are open too much thus exposing the ported vacuum hole within the carb’s throttle bore at idle.

Lorena, Texas (South of Waco)

You should find out what they did to it at the shop you took it to.They fixed one problem and created another by the sounds of it.