I want to change my 2-barrel Rochester to a 4-barrel. I have the correct manifold, but I’m not sure what to do about the air cleaner. I want to remain 50 state street legal.

I had planned to purchase a used 4-barrel ThermAC, but could I run the open element type found on the ’68 Z28 without running afoul of the law? This would involve removing the 2-barrel ThermAC without replacing it with a 4-barrel one--does that constitute an emissions violation? My guess is if I want to have the 4-barrel on my 327 I have to get the 4-barrel ThermAC, but I could use the open element if I used a 302 in place of the 327. Is that a correct understanding?

Thanks in advance for the advice.

Different states have different rules. Most state exampt cars over a certain age. The laws vary all over the place. As an example, the county where I live, cars as old as our are 100% exempt, but when I lived one county closer to chicago, I had to have a sniffer test every other year. Even when I had to be tested, Illinois DOES NOT open hoods, ever.

If you are talking about making the car 50 state legal according to 1967, 8, or 9 laws, then the stock 4bbl thermac air cleaner is your answer, includin g a sealed PVC system if your car is 68 or newer.

If you are talking about today, you got some studying to do. There is no such thing as a common standard for 38 year old cars.

Exactly what year / model / engine car we talking bout anyway?

Here in MO, my car being a '67 only requires the PCV thing and I can run an open element air filter! I think '64 and older cars can still run the old stinky, steamy road draft tube too b/c it pre-dates a pcv thing...

Now the '68 and newer cars have to have the stove on the air cleaner intake pipe.

I think legally that you will find that this is a fed reg. even if your city, county or state tends to ignore it so if the fed guys wanted to, they could nail you and call it "tampering"!!

pdq67

Different states have different rules. Most state exampt cars over a certain age. The laws vary all over the place. As an example, the county where I live, cars as old as our are 100% exempt, but when I lived one county closer to chicago, I had to have a sniffer test every other year. Even when I had to be tested, Illinois DOES NOT open hoods, ever.

I live in the same county as the city of Chicago. I am exempt for the test by having antique plates. Even when I took the test with regular passenger plates, I was not even close to failing. There may be this type of exemption in your state.

We have that here too in MO, but to me it severely limits us as to how much and HOW we can drive our old cars if so plated.. Which is just what they want to do!!

There are generally two smog check programs that should be enforced everywhere unless cities, counties and states as said earlier tend to ignore them.

The regular attainment areas fed.reg's that apply to all cars back to I think '64 that say's that all cars have to have their factory smog stuff on them or they won't pass a visual! This is where the "Tampering" reg. come's in!!

Pre-'64, you home free to do anything that will allow you to pass a safety inspection if you have too!! (Read, NO 3-foot tall blower sticking through the hood so big that you can't see around it!!)...

The second "Program" is the Inspection/Maintenance Programs that have to be fulfilled if the area of a state is deemed out of attainment for CO and Ozone.

There are several levels of these programs, from just a basic tailpipe sniffer probe like the "Bar-90" to an enhanced, centralized dyno-run trace like the "I/M 240" and now to the '96 and newer cars "OBD-II" program where they just read out the info stored on the newer cars control modules and deem if everything is set right, that it is theoretically running right so therefore is clean from a smog test standpoint!!

Hope all this stuff is of interest to somebody b/c I feel if we don't know about it, we just may lose the rights to drive our old cars!! (Read, "Crusher Legislation" here!!)....

And guys, this stuff come's down from the fed. level b/c if state's don't fall in line and do what the fed's want them to do to clean up the air, they threaten to pull the Fed. Highway funds from them and this is SO much money that state Legislators foam at the mouth!!

This is why I keep saying VOTE all the SOB's out of OFFICE!! When is the last time you saw somebody dying on a street corner from BAD AIR????? And the EPA themselves keep proclaiming that our air is cleaner than it's ever been as they keep tightening DOWN the Criteria Air Pollutants which just make's it harder and harder, (read, more expensive), for business and industry to exist in this country!! CAN you think, more JOB outsourcing here!!! BUT since I figure 45 percent of us work in some way in the public sector, we will do whatever the people in power in the public sector tell us to do b/c we don't want to break our own "rice Bowls" b/c there aren't very many GOOD jobs left in the private sector like there use to be prior to 1970, the enactment of the Clean Air Act!!

Boy, I'm really on my soapbox this morning..........

pdq67