Couple of stupid questions.

What is a "Lockup" and how do you adjust it? I've never even heard of it.

How do you know that it's rich for city driving? Are you looking at the spark plugs or is there some sort of other way to tell?

Lockup is a feature added to some transmissions to save fuel. At a set rpm in 3rd gear, the special torque converter will 'lockup' and not allow slippage. This feature was worked into the 904 transmission in the late 70's transmissions such as the a999 from an early 80's dodge truck that I have installed in my car.

The lockup could be adjusted with a spring change, but I mistakenly removed the sping and disabled the lockup because I was told it wouldn't be good for racing. I later learned that the lockup feature won't activate at full throttle, so it was a better idea to keep the feature for gas mileage.

Can't you tell? When my car is running rich, it will easily chirp the tires when I pull out into traffic and the throttle response is fast through the whole rpm range. It's also easy to tell based on the mileage. Yes, the plugs also get darker than they should be. Usually the #1 and #6 plugs would get white in a lean engine, but mine used to be dark all the way across the range.

With the new carb tuning, it's running lean in town. No power until you stomp on it, and lots of hesitation at light throttle. I can always adjust to make it a little more fun again.

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1980 Aspen 225 super six

Thanks for the explanation.