Vacuum advance problem?

[STROKEDPONY]

Hi guys & gals. I just picked up a 95 stang for a parts car. The previous owner installed a 302 & C6 trany from a 79 F150. The car is super clean & now that I've been tinkering with it will probably drive it but here is the problem; the motor runs slightly rough & smells gasy . It does puff bluish black smoke ever so slightly . Higher rpms it seems to come out of it or be less noticeable . The vacuum advance line to the distributor was disconnected so i pushed the rubber line back on & it started runnin g really rough & died . I pulled the rubber line off & it smoothed out some . I tried this 3-4 more times with the same result . Do vacuum advances go bad ? The motor supposedly only has 91k . The previous owner said he could never figure it out either . So what are my diagnostic steps ?
I checked for vacuum leaks found none & the Qjet 4bbl was supposed to of been rebuilt just weeks ago .
Thanks !:undecided:

 

[99GreenStang]

Ill try and help you . Never believe ANYONE when they said anything was suppose to have been rebuilt especially a carb if you have another laying around I would def throw it on and see if it improves which I bet it will seeing that your getting a smell of fuel with current setup. You can check your distributor vacuum advance by leaving the line connected to the distributor and take the other end of the line and suck through it and if it becomes impossible to suck more air through your advance is good if you can keep sucking then its bad . Also take your lines off and spray some cleaner through them or replace them make sure their not clogged up .

If it's hooked to the proper port, there will not be any vacuum to the advance unit at idle; it should only be advancing after the throttle is opened. Check with a timing light. Read timing with vacuum hose off. Then read timing with hose connected at idle. It should be the same. Next hold the throttle steady at about 2,000 RPM with the hose off and read the timing. Without changing the throttle, connect the hose. RPM should increase slightly and the timing should advance. Too much tiiming at idle will cause pinging and a very uneven idle. I have seen engines die because of a broken wire on the pickup coil inside the distributor. When the advance unit moves the plate, the pickup coil wires flex and if one is broken inside its insulation, it looses contact. If your timing light is hooked up, it will quit flashing as the engine dies. If the problem is too much advance for the engine to run, the timing light will continue flashing as the eingie dies.