quadrajet 455ho

[ss3011]

Originally Posted by Jeff Stout

I always thought the opposite. Unburned fuel from 2 step going out exhaust and making a rich condition. My bracket car has a O2 reader and on 2 step it is rich and gets right by second gear shift. Yes on to big primary with no rods.

In a production car , when the engine misfires the O2 sensor reads lean , and then starts to add more fuel to correct . Most production calibrations will only allow so much correction , and once it reaches that limit , it sets a code . A misfire is similar to what a two step does only more controlled . I am surprised your engine reads rich when on the two step . Hopefully a few more folks will chime in with their experiences .

As far as running as big a jet with no rods , I agree , too big , but remember that this particular carb has the POE system , which adds even more fuel into the primaries at WOT . He might have to put a very small primary jet , or reinstall the power piston and primary rods .