AVS2 tuning

mbaird said

I just bought a new AVS2 800 for my 360 and I am confused on the tuning .
My wideband reads 12.5 @ light cruise so I dropped main jets to .101 from .104s but its still rich. So I figure it may be the step up spring because my vacuum at idle is 13. So I replace the stock spring with a lighter one .( or what I think is lighter... this color coding thing is bullshit as they all look alike to me .).. still rich .
I will try some bigger rods but I am already at the edge of the chart .

I ran a 650 version as well that I finally got running clean down low but top end was soft compared to my holley 750vs .

These carbs are said to be easy to tune compared to a Holley but I think thats BS.

Can anyone illustrate a step by step procedure for tuning these?

Click to expand...

I you use a smaller main jet, you lean out cruise and WOT whether you want to or not. If all you want is to lean out your cruise, grab a pair of calipers and measure the metering rod you have now on the fat part. Whatever that is, you want a metering rod with a .004 bigger diameter there, and the same diameter on the small.

If you can’t get that, you have to do the math and find a main jet that gets you .004 on cruise and has the same WOT size you have now. Which means the WOT part of the metering rod needs to be .004 bigger (or whatever the number is that you are trying to hit) so you only lean cruise and not both cruise and WOT.

That chart is a PITA. I measure every metering rod. I’ve found some that aren’t what they claim to be and that can jack you up.

You are dealing with the springs, the main jets, and two different diameters on the metering rod. You have to juggle all that crap until you get what you want.