Are there any tricks of the trade to make a giant cam pass emissions? I mean something like the GM847 type of specs.

 

i dunno if it applys to big cams, but on my old jeep i will toss a bottle of rubbing alcohol in the gas tank. always passes with flying colors

 

You need GOOD cats consider keeping a pair just for testing., an "emmisions only" tune is another alternative if your tuner is willing to help.
Freshair pumped into the exhaust prefferably after the O2s.
Use a 180s stat and either set the fans high.

 

GM847 with every possible trick in the book will not pass emissions. You may get it close, buts its going to be ULTRA hard. I have roller emissions in CT and I had a hell of a time with a hotcam and a 383, though mine was running rich due to a host of problems. I got it to pass.

If I were to try, i would do this.....

A BRAND NEW CAT as close to the manifolds as possible, either off of a shorty header or manifold

180 degree Thermo

Lean tune from your tuner

2 bottles of rubbing alchohol, in 93 octane gase

change roller rocker ratio, this will lower the overlap area in the cam lobes.

 

I went emission exempt...