After reading this article while trying to tune my Holley 750, I liked his idea of adding a oxygen sensor & using it for jetting. http://www.bob2000.com/carb.htm Look about 1/2 way down the page.

I just finished building a 2 1/2" X-piped exhaust system this afternoon for my car & drilled a hole in my drivers side header & welded in a bung. I didn't have any chances for full power runs but on street cruising & a few 1/2-3/4 throttle rides I've noticed my readings are usually in the 880-960mv range. Idle is near 450mv most of the time but as I crack the throttle, it jumps almost instantly to the 880-960 range.

This is telling me I'm running rich but not too far off from a perfect 14.7:1 ratio.
I'm wondering if others have played with this idea & where they found the best performance levels to be at.

Thanks.

I use two in my exhaust system-left and right and I switch between the two for the readings. Yes, it helps give you the best performance with actual readings to back it up with. I run the Autometer one and instead of paying extra money to use "their" O2 sensor, I got one for a 1995 Chevy truck with a TBI350. It is a three-wire also. I too ran a little rich both at idle and WOT but a change of a 5.5 pv versus the 6.5 made the difference for me. -Jabin

I built mine with the SG-12 sensor(one wire) & a cheapy LCD multimeter. Total cost was about $50.

What's the advantage of a 3 wire sensor?

What you are using is not a wideband o2 sensor. It is a narrowband o2 sensor. That is why the curve only has a good resolution right about 14.7:1. Because it is designed to keep it there using a fuel injection system. A wideband sensor gives you a MUCH more accurate picture of what is going on. They also cost a lot more. The sensor itself is the biggest fee, but I have plans on how to build the box for cheap. There is a DIY wideband kit online at www.diy-wb.com (http://www.diy-wb.com.) The box allows you to hook up to a digital multimeter, but gives you mucn more accurate readings than using a narrowband.

I have used his method before and find it to be very cumbersome unless you have somebody watching it for you. I just tune the main jets for best vacuum at about 3000RPM in high gear, the secondaries for best MPH, and play around with pump cams, and accel pumps until it feels good.


[This message has been edited by marsfrogie (edited June 04, 2005).]