It fooled us for a bit. My 93 came non-walled too.

All 93'* have the digital (old style) EGR and non-roller pivot rockers. 93 L27'* got the rollers though.

so will 93-95 L27 and 94-95 L67s all come with roller rockers? how much of a difference in performance would that be over the 92-93 rockers?

Yes, 93/94 L27 and 94/95 L67 have rollers. They are a direct swap to 93 L67'*, but NOT 92 L67'* without a cylinder head swap.

Performance? No more than 5hp. If that.

Will, are the L27 rockers the same ratio as the L67? I know of a couple scrapped L27s I could steal rockers off of, but no 94/95 L67.

I believe the rollers to be more of a longevity and noise reduction move on GMs part. The added HP is a byproduct.

But here is a question for the masses, and it'* a viable one. For the sake of arguement, lets take 2 L67s S1s. Everything between the two are the same, except that one has type "A" intake manifold, and the other type "B". Now then, would GM have created a new PCM instruction set for the new-style intake?

Here is why I ask: The HP/Torque ratings for all of 1993 stayed the same, regardless of the manifold. So, using that logic, no engine is better than the other, performance-wise. Experience tells us that a taller intake *should* net a slightly stronger low-end torque (which, as stated, the walled intake is a tad taller). The walls *should* also provide a straighter path for air to flow into the head, which should increase torque again, and a slight advantage in fuel efficiency. One would think GM would have further exploited that design through modifiying the PCM'* program.

And I haven't seen any S2 L67 LIMs, so I ask the question "Are those intakes walled too?"

Yes, they are the same ratio. Amazingly, the valvetrains between the two are identical. Same lifters, valves, springs, pushrods, and arms.

Keep in mind that rocker bolts are not re-usable. This will require new bolts if you intend to swap.

S2 L67 (both L67 and L32) are non-walled.

The walls in effect create a longer runner, and while they may provide a 'straighter' path, they also provide more of a restriction for the air to enter them to begin with.

I'd personally be very surprised if GM wasted their time in optimizing a PCM for something like this. They sure didn't waste their time cleaning up the ugly L36 LIM.

To me it almost looks like the walls hold up the "ceiling" of the 94+ LIM, if you will. Maybe they're a structure/strength thing?

As stated before, no. They're very liikely acoustic. There are no strength issues with the non-walled LIM'*. The threaded bosses for the SC attachement are fully reinforced and supported. There have been no issues with a LIM failing either, and the S2 doesn't have them.

Good point. I forgot about the Series 2 not having them. Will, do you have both styles? Is there really any acoustic difference? It seems like needless expense for GM to redesign something like this.

I have both types. Several of each. My SLE was walled originally, but now has the Zilla'* hand-me-down non-walled, while the Zilla has another version ported for the ported heads.

I never paid much attention to the noise at idle between the two, but the SLE may have been slightly quieter originally.