My most important thing is it needs to pass emissions through Air Care Colorado.

I was thinking to get the ZZ4, and an XE256. I'd pull the ZZ4 cam out and put it away until it's emissions exempt so that I can still use the comp controlled stuff and have adequate vacuum for the ECM. Or when the time comes maybe buy a higher performance cam. I'll use the ZZ4 with the XE256 and have all of CCC stuff still on it. I'd also rejet the carb for the 350.

Will the XE256 throw anything out of whack on the ZZ4? I know it will have less performance.

Matt

 

i'm not sure if your aware of this, but the zz4 swap is and emissions legal swap that gm sells. just copy fairly closely to what they include in the kit and it won't be a problem. go to your local gm dealer and get a performance parts book. it's in the front area of the book. with some skimping on parts you can make it work and not take that cam out. it will still pass emissions.

 

You wouldn't have to do much to get it to pass with LG4 equipment. The cam isn't the main hurdle. Getting exhaust gas to the EGR is, since the ZZ4 heads don't have cross-over passages.