Just some general background:

Swapped in a 350 Caprice crate motor from Scoggin Dickey to replace my 305 and installed the following mods:

TES Edelbrock Headers
LT1 cam
1.5 Pro Magnum Roller Rockers

Emissions problem:
I failed smog with high HC and NO. I know high HC is due to unburnt fuel and high NO is related to running lean. I know one reason why I am failing:
still running 19# injectors at stock pressure


Temporary solution to pass smog:
Bump up fuel pressure with AFPR

Questions:
1. I haven't changed the 305 prom or the 305 knock sensor. Is it absolutely necessary to change out the prom or knock sensor to the 350 components to pass smog?
2. How will I know what my air/fuel ratio is without a scan tool/auto xray? Could I check the voltage on the oxygen sensor and if it fluxuates between the .1V and .8V during idle, is that enough to say I'm running at the appropriate mixture?
3. When I'm in park and I give it some gas, my O2 sensor fluxuates in voltage. From reading the forums, this is enough to say that the O2 sensor works and it's not stuck at one voltage. But, is it enough to say my O2 sensor works and leave it alone or is there a calibration issue and I should replace it anyways?

Thanks for any help in advance!

 

Is the car still equiped with a catalytic converter?

 

I'd assume it at least still has a shell of a converter, since they won't sniff it if it doesn't pass visual. Whether it's got any guts in it is a different matter.

Lean is one way to fail NOx. Others include a malfunctioning EGR valve or rich mixture. High HC is unburnt fuel, which typically is indicative of a miss, or to put it a different way, something other than the actual fuel mixture.

I'd guess you have more than one problem. Make sure the ignition is up to snuff. Leaking injectors will cause these kinds of problems. A gutted, clogged, or burnt-out cat will cause you to fail. I seriously doubt the 305 knock sensor, injectors, or fuel pressure are involved, though.

 

When I put in the 350 I also got the injectors rebuilt at cruzinperformance.com. I also got a new catalytic converter replaced right before I did the swap which was during the fall of this year.

When I put on the headers, the insides of the cat (at least on the header side) still looked like a "honeycomb."

five7kid:
When you said "miss, " meaning misfiring? As in not igniting the a/f mixture?

Also, any input about the O2 sensor? My friend thinks it's the O2 sensor, but I keep telling him that it works, and it's not stuck at one voltage. Is there any other reason to replace the O2 sensor? It hasn't been replaced for at least 50k miles.

 

Yes, I meant "mis-firing".

I'm a wee-bit weak on the specifics of O2 voltages, but I do know that not working properly is not limited to stuck on one voltage. I.E., it may be too low of a voltage.