Filter impact on O2 readings and stuff

[mtngoat]

So thought this might provide some interest....

 

I got tired of dealing with the separate filters on the L20b with 38's on it. Too small, too little surface area, in really wet conditions they don't flow well and in the summer on dirt roads they clog up pretty fast. Differences between filter buildup always had me winding up with tweaks in different directions for the mixture nuts. Annoying.

 

So I swapped back over to an old SSS style homebrew filter contraption i whipped up from two sheets of 1/8" Aluminum. Cut holes in the right places and you just sandwich a garden variety NAPA oval filter in between them in the usual manner. For one thing a lot more surface area, for another equal flow to both carbs.

 

So anyway I was marveling at how different the mixture settings are...unless I'm looking at this wrong, the larger filter flows way more air because I had to richen up the mixture by 1/2-3/4 turn from the usual settings. When I swapped over and went out for a drive, i didn't even get down the driveway before I had to richen it up...thank heavens for WO2 meters.

 

Comments or insights welcome

[Tristin]

Man, for saying you created a custom piece, there sure are so few images in this thread :poke:

[Laecaon]

Man, for saying you created a custom piece, there sure are so few images in this thread :poke:

 

Remember my acrylic filter? Like that, but aluminum instead of acrylic.

[Tristin]

Im pretty sure I know what it looks like. Im just saying... there should be pictures. 

[mtngoat]

I'll post a couple pics. It's ugly but it works OK. I've been rather surprised by the performance since i did my first long drives over the weekend with this thing. With the mixture nuts needing to be so much richer I was wondering what was going to happen with my mileage. However, the mileage has distinctively improved though I haven't quanitified it yet. All I know is that on my bi weekly 120 mile round trip I have at least a gallon more left in the tank than I did with the two separate filters, and I'd been running them for a couple years on the same trip and had them pretty well dialed in. The car also seems to pull a bit harder and at cruise on the interstate I'm pulling more vacuum than before. All I can conclude is that I'm flowing a low more air now and in spite of the richer initial settings the engine is running more efficiently now. I can't say I hate this outcome!