Playing with a wideband

[madkaw]

Well I finally got my car together and get to play with my newly installed wideband. How sweet to dial in your idle based on your AFR. My car is idling right around 17.5. Cruise is around 16 and the AFR drops as I get into the throttle. I actually thought my car was running rich at idle with my SM needles, but I ended up turning out my mixture about a full turn to get the mixture correct. After setting idle correctly, everything else seemed to fall in line. I still have more experimenting to do, but this is fun.

[ozconnection]

Well I finally got my car together and get to play with my newly installed wideband. How sweet to dial in your idle based on your AFR. My car is idling right around 17.5. Cruise is around 16 and the AFR drops as I get into the throttle. I actually thought my car was running rich at idle with my SM needles, but I ended up turning out my mixture about a full turn to get the mixture correct. After setting idle correctly, everything else seemed to fall in line. I still have more experimenting to do, but this is fun.

I would love to know how you got your engine to idle at 17.5:1 AFR???

If I tried that with mine, it would be spluttering and nah it would stall.

Go and listen to your exhaust and tell me how smooth its running. If it sounds like mmmmpmmpmmmpmpmpppmmmm then it's lean, probably too lean, well, too lean for me and my setup anyway.

I run around 12.5 AFR in my Datsun when it's up to running temperature. I'm curious about your setup because what you run is so far away from what works on my L28.

Cheers.

[240260280z]

I tuned a few Z's with O2 sensor and ~ 14.7 at idle worked nicely.

For balancing you can do Norm's test and lift one carb piston at a time to completely to disable it and compare O2 between each non-lifted carb+ all that extra air from the hole you make. A/F goes to 27 or something crazy lean but the readings should be same for each carb when balanced. You can do this at idle and at 3000 rpm for completeness.

[madkaw]

sorry guys, but my dislexia had kicked in:stupid:. The car did idle at 17.5-infact I really hadn't touched the mixtures since the 3000 miles I put on it last year. maybe that's why i got almost 30mpg driving to Zcon. I did readjust the mixtures to about 14.5 at cruise and idle. I also realized that I didn't sync the carbs at 2000 rpm and they were way off. So I was running at 17.5 and running mostly on one carb---no wonder my MPG was so good!!!!

I wish i had 2 sensors, but now I will need to pull the sensor from one side of the duals and hook it up on other side to compare.

Edited May 20, 2011 by madkaw
adding stuff

[madkaw]

Steve,

being doing a lot of reading on AFR's and I think I'm going to swap out my SM needles with some stock needles. You might gain some flexibility with your tuning starting from a leaner point. I have a smaller bottom end, but probably a better flowing head, so it will interesting how it will effect the engine. I believe my AFR's are a bit rich when WOT at the upper rpms which would make the engine lethargic to rev.

I plan on taking my car to the dyno again shortly and I will bring both sets of needles to see how the HP changes with the 2 set ups. Once I get the timing right for best power i will try and see what the best AFR is for my engine to make power. from what i read the number is NOT the same for every engine, but for the most part folks go too rich thinking it would make more power.

I remember when I use to race go karts that had 3hp briggs and Straton engines. After some modifications we would get the most power out of those engines at a leaner state. In fact we use to run them at 7500-8000 rpms at around 450 degrees+ all day! They loved to rev at a leaner rate-the hotter the better----