really stupid air fuel ratio question

[Sam K]

So I borrowed an Innovate LM-1 wideband and I'm determined to finally get my bug dialed in really well before summer. I've been told that 14.7 to 1 is an ideal air fuel ratio and I've read that air cooled VW's like to run at around 12.5 to 1. What I need to know is which way is richer or leaner. For example I took my bug for a drive and held it at a steady 3000 rpm's on the freeway for a couple miles and the wideband read between 10.8 and 11.2 on average. I thought this was rich for some reason so when I got to my destination and changed my main jets from 160's to 155's and on the way home it seemed to read between 10.4 to 10.8. Before I go any further with this I think I need to figure out which way I need to go.

For the record, I'm running IDA's with 37mm vents, 110 idle jet holders with 160 idle jets, 155 mains, 210 airs and F2 emulsions. The engine is a 2332 with 9.5 to 1 copmression 44 x 37.s mm heads and a web cam with .492 lift and 312 duration on 108 lobe centers. The car is a fairly heavy 67 bug with stock-ish gear ratios. It runs fairly well but I've always thought it could be better. I've never been that great at fine tuning stuff, though, so this might be tough.

[SlingShot]

Lower number=Richer Mixture

[Bruce]

Since it got richer, check both sets of jets to see if either have been drilled.  Otherwise, it's telling you to use a 150 main next.

[Rasser]

Full throttle should be 12-13 from idle to max rpm.  (main and air jets + emulsion tube), and on cruising you can go higher on the AFR without worries (it´s also more economic)
.
If you can (or dare), use 4. gear to dial this one in, or use 3. gear and have a friend monitor the readings while you drive. Don´t be fooled by the acc. pump that probably richens the mixture when you push the pedal - pedal full in from low revs.

When you have the e-tubes, main and air jets (and venturis) dialed in - then it´s time for some gentle cruising (very light throttle, low gears, low rpms), in order to dial the idle jets in.
Your engine is doing a lot of the cruising on the idle jets alone, so don´t think the main jets is all that pushes the car forward (my car will go 110km/h on ONLY the idle jets alone - 1971ccm, "small" camshaft). You can take your main jet holders out of the carbs, and see for yourself how much driving can be done on the idle jets alone.
You can also clearly see the transistion from idle to main if you pay attention to the gauge and have a steady right foot (this will also tell you whether you could benefit of a 3. progresssion hole - amongst other things like float height adjustment and so on.
Dialing in the idle circcuit on a pair of IDA´s is the difficult part, and will take a lot of time to get spot on!

Before doing any of this, be absolutely 100% sure that the carbs are synched perfect. Even the slighest difference will alter the readings, especially when cruising slowly around and dialing in the idle jets.

Ever thought about changing to a set of bigger vents, I THINK you might pick up some extra HP in that change?!   40, 42 ??

[Sam K]

Thanks for the advice, guys! I'll pick up a set of 150 mains and a jet size gauge today. I have thought about bigger venturis. I think I have a set of 42's in my other IDA's. Would it be wise to change them before I continue with my jetting?