Non-feedback exhaust?

[Bob_K]

I was looking through the CARB EO's today and found http://arb.ca.gov/msprog/aftermkt/devices/eo/D-200-3.pdf
which says that you can use Doug Thorley Headers (models 350 or 375Y) on a 75-79 Vette that are "non-feedback applications" . These are full length headers. What makes a car a "feedback" application? Also, how do I find out if my car originally had "feedback" equipment. When I bought it it had some aftermarket headers and no smog gear. I'm trying to get it back to legal and would preffer to not use the original style manifolds, but will if I have to. Any ideas? The car is a Canadian L-82 if it makes a difference.

 

[drags1998]

Im going to guess at this one !!!!!!! FEEDBACK is refering to an eletronic FEEDBACK CARB. Trust me, If I am wrong, someone will jump in!!!!!!!!!!!!!

 

[Bob_K]

I was thinking either that or maybe one of those cats with the extra pipe. Here's another guess for people to correct: Q-jets (non computer controlled) don't use feedback, right? I don't remember reading about feedback in my Q-jet book anyhow, but that was quite a while ago.

 

[brusso]

A "Feedback" carb has a throttle pos sensor that sends the ecm the rate of openning throttle as well as its position. Then the ecm tells carb to enrich fuel mixture like a mech acceleration pump. Also the car is equiped with an O2 sensor for sensing fuel mixture at idle speeds, in turn telling ecm how much to adjust carb idle mixture. In other words, the carb that has wires connected to it.

 

[Bob_K]

Wonder if California would get upset if I yanked the heat riser butterfly valve when I put these in. I don't see a way to save it. After all, they said it was OK to use these.

 

[brusso]

I went with an off road exhaust (no cat duels) straight to the manifolds. Well, I kept the heat riser and had it tack welded open. I just didn't want the hassel of retorquing the header bolts every so often. Coming from stock exhaust, it made a noticable differrence in top end performance. I also love that flowmaster "40" noise.