Idle Rpm High in Park, Low in Drive
with stock 360 distributor (vac advance)
For the moment we'll have to assume the advance curve has not been messed with.
However, unless the tag is still on the distributor, we don't know what that curve is.
If its from the early smog era, then it may have a very fast and long primary advance.
IF that's what it has, and the cam is mild enough that the manifold vacuum is strong at 650-750 rpm,
then
set the base timing much lower, maybe around 5*BTDC
and use manifold vacuum on the vacuum advance.
That will bring timing at idle speeds into the range 12 - 18* BTDC.
a wideband in the car (idle IN GEAR at about 13.5-14.0 afr, slightly richer in park)
A little lean for non-smog idle but its in the ballpark. WBO2 are not always accurate interpretors of AFR so don't sweat the number. Just use as a reference when you make changes.
Intial timing, idle speed and idle afr set for highest vacuum, smoothest idle and best afr.
Best AFR is the one that produces the most power. That is checked by losing the least amount of rpm when placed in gear. Another way to look at it is the highest manifold vacuum in gear.
Reconnect vac line in park, rpm spike to 1300-1600 rpm. Vac line connected and dropping into gear, rpm drops to almost 600 and car wants to stall and die,
Timing and fuel mixtures work hand in hand.
Adding that much advance lit off the cylinder so early it wasn't even in the ball park.
It’s connected to full manifold vac (per everything im reading, including professional recommendations, full manifold is perferred to port)
Well you can stick with them, or go with what works.
I have tried retarding/advancing timing with vac hooked but it either increases rpm slightly or makes the car die.
because its not close enough to adjust anymore.
