Smog equipment or Cowl Plenum

[fireZ]

I just acquired a 68 Z28. The car has all smog equipment intact and also the couple had a cowl plenum that came off another car they had but is long gone. Would it be best to install the smog equip. or go with the cowl plenum. Car is pretty correct otherwise. Thanks for any thoughts.

[RAfbody]

If it is a factory 68 cowl plenum, why not install both?

[fireZ]

The passanger side smog tube will not alllow breather to sit correct on the carb. Jerry Mac answered this question a while back. They were not made to work with each other apparently

[bertfam]

HERE'S that thread.

If it were me, I'd leave the smog stuff on. When's the last time you saw a car with original smog equipment still on it!!!

Ed

[Stingr69]

I would pull the smog off and add the cowl plenum. NOBODY has the cowl plenum and NOBODY that ran a cowl plenum back in the day would ever keep the smog on there at the same time. Smog does not physically fit with the plenum box and it makes no sense from a performance standpoint to have them both on the car at the same time either.  Also, it leaves the door open to a set of period correct headers if you desire that.

If you don't do that then the next best thing would be is to keep the smog on and for the cowl plenum to be loose in the trunk as it would have been delivered. You could make a case for that "as delivered" condition but that isn't as much fun if you ask me.

Pet peeve of mine - Z/28's with the cross ram and stock exhaust manifolds. Nobody would have done that back in the day either but you can see it now.

Hope this helps,

-Mark.

[x66 714]

If the car is pretty much correct now...why modify it? I would never install anything into or on a car today that requires cutting. Just another opinion.

Would like to hear more about what you bought though

Joe

[fireZ]

Thanks for all the thoughts and ideas

[68camaroz28]

Know exactly where your coming from as I had the issue. Our 68 had the cut out and air cowl plenum when purchased 30 years ago but of course no smog set up. The third owner purchased the car but never got the plenum set up (long story) even though the car lot said they had it. In 79 an orig. one was purchased via Hemmings Motor News for the car back in 1979. Then around late 2003 or early 2004 I purchased a complete smog set up from Jerry only to find out some months ago that it would not work. Since the car had air cowl set up installed no way was I going to patch the cowl so I easily decided to go with the cowl plenum but purchased the repro Kustom Headers. The orig. owner had put Stahl Headers on and still has them. But in your case I would not cut the cowl to put the air cowl plenum air cleaner on if it is not cut currently. Keep that smog set up on and the air cowl plenum set up is worth quite a lot if it's all original so you have a winner in that regard if you decide to sell. Of course you could put it in the trunk for display