Is there anyone that can tell me how to tell the difference between the two? I just picked up a 94 Z28, but noticed that there is a vent tube going to the intake elbow. I just need to know if he just upgraded with a vent tube, or actually converted his opti. Are there seperate codes on the two that would help me?

 

I think the 94 was a split year with a change to the vented in the later part of the year. Check the pictures and you will notice the extra hose on the vented ones.

 

In f-body cars 93-94 were non-vented and 95-97s were vented. There were no midyear changes.

The previous owner could have vented it or even put an MSD cap on it (that makes it vented). Or it could have a complete vented conversion to the vented style.

There are some pics on my Tech Page in this section: http://shbox.com/1/component_location_views.html

 

No. I have one of the last 94's made. It had an unvented Opti.

 

My Msd Pro Billet has a part number for 93-94 and one for 94-96 so i assumed they made both. I bought the late model one and it was vented and mine car is a 94. Maybe the gm wasn't vented which is where i went wrong. If you both think im wrong then theres no way it could be right but it would be .
Here they are:
http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku

 

I do believe the only 94' vented LT1 motor was in the caprice/Impala.

 

Are you saying the 94-96 model didn't fit your car? It could be that way because of the Impala/Caprice which does have the vented style. Look in the description and it will say opti I and opti II. The 92-94 lt1 cars are different in the cam area of the opti. The timing cover hole is smaller because of the small spline piece that plugs into the opti and passes thru the cover. I think the vented MSD is a standard thing on all their billet opti's and could also be the same for the caps that are sold seperate.

 

As far as I know, we're talking about F-Bodys here. 93/94 F-Body was unvented. 95-97 F-Body was vented. Don't get confused by catalog listings for non-GM branded items that are made to fit the F-Bodys as well as the 92-96 Corvettes and the 94-96 B-Bodys.

 

Exactly. I qualified my post by saying f-body. B-bodies got the vented earlier.

 

No need to defend the posts. With all the interchanging of parts along with catalogs getting our years screwed up, who is to say he didn't get a transplant from a b-body. I understand he has a fbody
I tried to shed a little light to the original poster and I am trying to understand what mrmint69 was getting at in his post.