Ideas on smog issues with Zs.

[cuisinartvette]

Esp in Ca most cant pass anymore
Hib posted some interesting info about tweaking the tune some
Random thoughts

1-Dummy cam where only 1 intake valve can open/tune to suit?
2-Repop orig exhaust manis, so a late model GM truck/vette or HD cat could weld on? Shorty header with smog tubes-perhaps old cats just dont get it done like the 3 stage (term?) do. Seems to be less hassle more cost effective long term. FWIW an aftermarket cat (on my 02 5.3) puts out more emissions than a GM and they dont last.

Other suggestions? Has to be a way around this rather than making "smog" cams too much work and $ to be changing that out
Cant help but think if the airspeed was picked up wiht the right work/valve job in the head port and cam done to suit has to make it more efficient

Was a project been wanting to do forever...not convinced its the cure but pretty confident theres more power and efficiency to be had out of these without having a rumpity idle. Have the perfect person to join in this one
Finding the parts affordable to work with another story. Grinds in mind and unlimited access to a bench to measure port speed etc.
Anyone got an old head and 4 cams they wanna part with in the name of hackery?

Other idears?
Cant bring myself to chop up a brand new one.

[XfireZ51]

Not sure why u would need smog cams? The stock ))6555passed emissions.
As for eliminating secondary lobe, it would be easier to just make sure he secondaries don't ever come on-line.;

[mike100]

the best thing to do are new oxygen sensors, good cats, and a cheater tune.

The state lists the same certified CA replacement catalyst as the same unit certified for LT1 cars. I guess you could weld those up if you had to, but would probably need to remove the manifolds to do the welding.

even older cats can pass if the fuel mix is spot-on...then there's the cheater chip to lower ign timing and run the fans at a lower temp if you still aren't making it. less cam shaft overlap would raise the low speed pumping pressure and send the Nox through the roof. The stock cams are fine.

[cuisinartvette]

Maybe cats are the way to go
Guy that owns my old one cannot get his through....or said it finally did
Guldstrand supposedly rebuilt his cats for an absurd sum said"It passed" but provided no paperwork so have my doubts
As you said perhaps a newer/different style would do the trick

They def lowered limits when I had it always passed by a landslide
stock haibeck chip. Just thinking of ways to keep these things on the road its only going to get worse out here anyway

Im not in the market now but at some point this next yr will be looking for a real sweet low mile black 90 that I plan to make my DD.

They are just to cheap now so say no to.
Considered some real cherry 89-90 6 spd L98s it would be hard going back to that wimpy power level. Porting is free for me, oughta be enough oomph for a driver may even make a my own cams too. Know they would pass smog idle like a kitten and really pick up the torque everywhere

[Z51JEFF]

Tearing into the motor just to get it to pass smog? I'd rather consult a lawyer about looking into a class action lawsuit against the state for trying to kill my car. As stated,fresh 02 sensors,cheater chip and a few other things will get the car to pass. So Ive been told. As long as the state doesn't lower the MAX LIMITS I shouldn't have anymore problems. Last time I did a smog check the MAX LIMIT on the Nox level was 300.

[tccrab]

Well, I'm probably going to jinx myself, but so far I've not had any problem with "Girlfriend" at the smog shop.
She's fairly stock, and low miles (13,500) the only mods are a Haibec prom, Accel injectors, and Flowmaster cat back exhaust.
I do remember that I was pretty close to the nox value last time, but passed with no problem.
Personally, I can't wait until I fail, it'll give me the opportunity to put on headers and aftermarket cats, and then fight with the smog referee.
Just because it fails doesn't mean the car gets written off.
All you gotta do is present a clear, honest and concise case to the referee and you'll get a pass.
All bets are off on highly modded cars.
You might get away with a ported plenum, injectors and a special prom from Haibec, but pretty sure a stroker would be a problem.

'Crabs

[cuisinartvette]

The ref can help agreed. May need theirs to get my 02 truck tagged
Code cant get rid of for yrs nothing wrong with it. Wiring somewhere

All you gotta do is present a clear, honest and concise case to the referee and you'll get a pass.

Their is a consumer assistance program 1 866 272 9642 that can aid with up to $500in repairs however if its fail after fail gross polluter goes on title I believe then they call you in ea yr. Happened with an 80s vehicle I owned.

Former owner of my Z tried the header deal with our ref and they referred to their national parts locator. Found him two manifolds with cats told him he had to.

Well one of the cats was bad...had Guldstrand "rebuild" one cost him a LOT hes got the same problem.

If they cant find parts then maybe on headers. someone mentioned a newer 3 matrix? Cat may do the job.

[Z51JEFF]

There is one owner that went the referee route,got a pass and now has headers on his car.

[cuisinartvette]

Who!!

In less than a yr I should be in a position to pick up a low mile 90....wont be leaving it stock for sure but has to be legal if I stay out this way

Would make the perfect daily driver! Last one proved itself have no worries

[Z51JEFF]

Who!!

In less than a yr I should be in a position to pick up a low mile 90....wont be leaving it stock for sure but has to be legal if I stay out this way

Would make the perfect daily driver! Last one proved itself have no worries

I can't remember who it was but it has been done. I just dug out my last smog test and the Nox lever at 15 MPH have was 527,almost over the limit. I remember asking the smog tech about it and he said to the reason was it was this or that but this was the first in awhile that it got that close.