I've had this car through the inspection lanes 5 times now, everytime they sniff it, i get a sample dilution error and they fail it. The first time i put it on my own 5 gas analyzer, the HCs were at 1600. Spent 10 minutes tuning the idle circuits on the carb and got them down to 185, which is low enough to pass (HC limit is 220 in my state). CO's are at .04%, well below 4.0% limit. Problem i'm having is i can't get the CO2 up enough to avoid the sample dilution error. The highest i've been able to get them with carb and timing changes is ~7%. You need either 8 or 10% in my state (DE) to pass. The car runs it's *** off, all cylinders firing, all cylinders are about the same temperature at the header primaries, and there are no exhuast leaks. I'm beginning to think the cam is just too obnoxious to get through. For the record this is an old race motor that was in my buddies monte carlo. Specs:

383 all eagle forged bottom end... 13:1 static compression
Sportsman II heads (i know)
Comp Cams Nitrous HP flat tappet cam. I can't rememeber all the specs, but it's something to the tune of 238/246@ .50" .490/.521 lift, on a 113 LSA.
Edelbrock RPM intake
Speed Demon 650DP.
It has two brand new cats on it.

Personally, i think it's hopeless. I don't think it's gonna get through without at least a cam swap, but i'm hoping someone has a clue as to how to get the CO2 up without changing components.

thoughts?
Eric

 

when is it failing for dilution?
if its failing at idle can you bring it up some?

 

Its failing low, but it doesn't give an acceptable amount of Co2 until about 1800rpm, so thats not an option.

Eric

 

maybe its because with that cam, the engine is not as efficient until higher rpm's. the combustion is less "clean" at low rpm's.

 

thats pretty much my assumption... i'm just trying to decide if theres anyway around pulling this cam out just for inspection...