Large RPM and Vacuum drop when shifting from park to gear
So, it turns out my car had wayyyy to much initial timing.
I checked it with the timing light and had 35 degrees of initial timing with the manifold vacuum disconnected!!!
Good Job!
The shop manual may cover this but allow me to mention it anyway. Most of the time, whether stock or hot rodded, timing is checked with the vacuum advance disconnected and the vacuum source plugged. Golf tees in the hose are favorite plug.
So I retarded the timing until around 15 degrees of initial. My car idles at around 1100, and putting it in gear drops it to about 900. I didn't go any lower than this, because I noticed my voltage drops too much if it idles lower (sub 12 volts).
If possible, start another thread on the voltage issue. Mention how and where you are measuring it and if any non-factory electric items have been added to the car.
In the meantime charge the battery with a charger. On a factory car, it can idle fine on 12 to 12.5 Volts (battery power) for quite awhile. You'll just need to recharge the battery with a charger when done.
I noticed that at these idle numbers, my timing is not constant. The mark moves between 15 and 20 degrees. My idle is lopey and rpms oscilate +/- 50 rpm. Could this lopey idle be the cause of my "unstable" idle timing? Or could my timing light be defective?
Timing light is probably OK.
The timing is moving because the distributor's mechanical advance begins somwhere above normal idle speed. Shop manual or emissions sticker in the engine compartment will have the rpm but 650 to 750 rpm is typical on emissions era engines.
Once you get the battery charged up, you can work on reducing the engine speed and adjusting the timing until its down where it should be.
Since the carb has been changed, I'll assume there is no idle solenoid. Yes?
If so, then try reducing the throttle position using the throttle speed screw, and experiment with as initial timing as low as 10*BTDC around 650 to 700 rpm.
If its a factory distributor it might have been set up with an advance intended for initial as low as 5* BTDC, again around 700 rpm.
