L-Jet going full Rich on Deceleration Options

[Brian Fuerbach]

1974 1.8 with L- jet. Been playing with a wide band air fuel meter and noticed that when I lift the throttle the AFR goes to max value on the gauge. I thought it was supposed to go lean. I checked the throttle position switch and it checks out fine. Going to check the wiring harness next.

What else should I check? Decel valve?

[Van B]

Your vac readings are what my decel valve yielded when my car was giving me high idle problems after deceleration. I turned the screw in until I got 20” and 23”.

Regardless, your numbers seem ok. Maybe it’s somewhat of a contributing cause, since we’re talking about a tuning issue and not a fault?


Throttle switch checks out. It doesn’t do anything between idle and WOT on an L-Jet. So, most importantly it does know that your throttle is closed. If it didn’t, I think you would have other issues.

Maybe that table I posted can help you improve your tune on the 123 distributor? Knowing vac levels for when the timing should retard or advance, and by how many additional degrees, as well as centrifugal data for the OE distributor would allow you to better mimic OE.

If that is all set up, I’d say the AFR you get is what it is and nothing to worry about.