i put a after market air filter on my car so do i have to keep the vacum motor or no or the air sensor?

The thermovac system on the air cleaner regulates the temperature of the air going to the carb. It helps avoid an off-idle lean condition very common with emissions calibrated carbs.

What does that have to do with an aftermarket filter you put inside the air cleaner housing?

i put a chrome filter housing.

ah, so your new housing doesn't have the ability to use the thermac correct? Then you can't use it, and the question is moot isn't it?

Well, all the older carb'd GM vehicles i've ever seen/worked on (not a huge amount, but nonetheless), i've only seen 1 thermac hooked up, and *** knows if it worked.... So yea, I wouldn't be too concerned about having it hooked up, it just helps your engine warm up faster.... (right?)

Anyway, I think sometime back in the day, (80's perhaps), when the great unwashed public figured out cold air makes a car run better, everyone went out and looked at their thermac, saw it going from hot exhaust to the air inlet, and thought: "this must rob me of power! I'll get rid of it!" and tossed that little chromy plastic dryer vent thingy....

When I first did the mods to the 305 in Nov '01, I didn't have the dual snorkel yet. I had run an open element during the previous summer when the engine was stock, and the single snorkel was a huge restriction to the new-found power - so I put on the open element. I almost killed myself at an intersection when the car was half warmed up and the outside temp was about 20 degrees. With the dual snorkel with functioning thermovac system, no problems.

On the rare ocasions when the car has been to the track, the thermovac vacuum line was disconnected and the port plugged. Otherwise, for street use (the vast majority of its use), the thermovac stays functional.