How to adjust vacuum and mechanical advance

[ekafrawy]

Can anyone point me in the right direction in checking my vaccumm and mechanical advance? and how to adjust it. I have the base timming set at 12* right now. The car is a 1971 AMC Javelin 360 4bbl.

thanks,

Eric

[donsjave]

Since I have a 71 Javie, what I did was pretty simple. Since you did not mention if you were checking on a new distributor, I will make the assumption that you have a new one.
Most vaccum advances will go up to 10* advanced and this is fine and proper. The mechancal advance is done by changing the springs that are just beneath the rotor. Going to a weaker (smaller) spring will allow the advance to come in quicker meaning that the total advance will come in relationship to the RPM of the motor. I run at about 10* advanced on the timing and I installed springs on my Javie that brings in the total advance in at about 2400 RPM. My total advance is about 32* and the engine seems to like it. With bringing the advance in quicker, it allows the engine to gain in some performance. Too figure your total advance, you add the timing plus whatever the springs beneath the rotor are rated at. You can buy the springs at just about any auto parts stores that stock distributors or they can special order them for you. The cost is relativiely cheap in comparsion to the performance that you will gain.
For your FYI the engine I run is a 401.