[Alibaba91]

The air fuel ratio is good in park or neutral, but way too Lean when I'm in gear or holding the throttle. I'm talking off the charts, over 18:1. I think the carb has too small of a main jet (61), but I want expert opinions before I start swapping jets.

65 Mustang 200 six cylinder coupe with C4 auto. I have an AEM wideband O2 sensor attached (blasphemy, I know), so I know exactly what my ratios are.

Freshly rebuilt Autolite 1100. Timing set with gun, idle speed with tach.

 

[rpm]

I'd do a 3 or 4 higher number change.

 

[Woodchuck]

Autolite 1100 with or without SCV?

Load-O-Matic or "dual advance" distributor?

Vacuum advance source coming from where?

PCV system or draft tube?

Static timing set to what?

 

[Alibaba91]

Autolite 1100 with or without SCV?

Load-O-Matic or "dual advance" distributor?

Vacuum advance source coming from where?

PCV system or draft tube?

Static timing set to what?

With SCV

Load-o-matic with Pertronix two, Pertronix ignitor, Pertronix wires, new spark plugs.

Vacuum advance coming from carb. (It's doing something, because when I pull to set timing, the timing drops)

PCV system (valve and grommet are new)

Timing set at 12 degrees BTDC, as per the shop manual.

 

[myfirstcar66]

Set it right for when it's in Drive unless you plan to only let it idle in Park... rich in Park is a place my car might be for 2 or 3 seconds at a time.

 

[66Ccode]

Also lean idle in gear wont hurt anything, all its going to do is stall if its to lean. Upping the main jet is not going to help..You need to go smaller on the IAB. What you can do is put a very very small piece of wire in the IAB to test to see if the idle improves..or find the IJ and up it or find the next size drill and make it ever so slightly larger..

 

[Woodchuck]

With SCV

Load-o-matic with Pertronix two, Pertronix ignitor, Pertronix wires, new spark plugs.

Vacuum advance coming from carb. (It's doing something, because when I pull to set timing, the timing drops)

PCV system (valve and grommet are new)

Timing set at 12 degrees BTDC, as per the shop manual.

Sounds good. Power brakes or not?

 

[Alibaba91]

Sounds good. Power brakes or not?

Manual brakes, manual steering.

 

[Woodchuck]

Manual brakes, manual steering.

Hmmmn.

Try disconnecting the vacuum modulator line and plugging it and re-check AFR.