Air fuel ratio Ljet Options

[Geezer914]

I am trying to adjust the air fuel ratio on me 2056 Ljet. I read the article that was posted a while back. I adjusted the wiper arm and set the idle at 1100 rpm (Raby 9550 cam) with the idle AFR at 13.2. When I check the high rpm the AFR is at 12.1. If I adjust the high rpm AFR to 13.2, (moving the large wheel 7 teeth CW) the the idle AFR is 16.9 with the mix screw all the way down. If I readjust the wiper arm to 13.2, then the high rpm AFR goes back to 12.2. Can't seem to find a happy medium. I know when you adjust the wiper arm it changes the mixture linear from idle to high rpm. How much more can I adjust the large wheel CW?

[914werke]

I don't ever recommend changing the settings on the internals of the AFM.

(IMG:style_emoticons/default/rolleyes.gif) Well, perhaps that is useful advice if you are working with a stock (1.8L) motor & the stock induction for which it was tuned in the 1970's (IMG:style_emoticons/default/sunglasses.gif)
not to mention the differences in gas formulation from then to now
or the likelihood of finding an unmolested AFM for a system that hasent been installed new in a car for over 30 years. (IMG:style_emoticons/default/happy11.gif)
But if you've spent a chunk of change on a motor and dont want to run the risk of frying that investment due to less than optimal air fuel ratio (IE overly LEAN) the only way I know to do that is with the use of a wide band 02 meter and judicious adjustments of those elements, fuel pressure, adjusted timing, ect.
With a system that is as sensitive to vacuum as L-Jet is, the addition of a non stock camshaft can add to the challenges. In my case Its ALL of that. (IMG:style_emoticons/default/headbang.gif)

[ClayPerrine]

I don't ever recommend changing the settings on the internals of the AFM.

(IMG:style_emoticons/default/rolleyes.gif) Well, perhaps that is useful advice if you are working with a stock (1.8L) motor & the stock induction for which it was tuned in the 1970's (IMG:style_emoticons/default/sunglasses.gif)
not to mention the differences in gas formulation from then to now
or the likelihood of finding an unmolested AFM for a system that hasent been installed new in a car for over 30 years. (IMG:style_emoticons/default/happy11.gif)
But if you've spent a chunk of change on a motor and dont want to run the risk of frying that investment due to less than optimal air fuel ratio (IE overly LEAN) the only way I know to do that is with the use of a wide band 02 meter and judicious adjustments of those elements, fuel pressure, adjusted timing, ect.
With a system that is as sensitive to vacuum as L-Jet is, the addition of a non stock camshaft can add to the challenges. In my case Its ALL of that. (IMG:style_emoticons/default/headbang.gif)

Just an FYI.. I had factory training on L-Jet back in the 80s. I understand the system. And I found out the hard way that the engineers at Bosch who designed this know way more about it than I do.

The air flow meter is designed to make the mixture richer with more airflow. When you change the spring settings in it, it changes the mixture curve. Rather than f**k with the insides of it, you can do things like increase injector size, or increase the fuel pressure to compensate for more displacement. And the difference between the 1.8 and a 2056 is not enough to cause an overly lean condition.

I have been running L-Jet on various 914 engines for 36 years. Never have I had an "overly lean" condition cause damage to the engine. And I have multiple air flow meters that have never been opened.

You can change things on your car at a your pleasure. And you can deal with the drivability issues that come with the reduction in spring pressure. I have already been down that road, and I was hoping to save you the trip.

Good luck.

Clay