Filter the results

The Mighty Caprice™ always had a funny rattle coming from the front left corner that I could never track down.  Since I couldn't find it, I figured it was something loose behind the bumper since much of the original underbody filler panels were missing.  After doing some driving in the Impala, which has all it's panels in place, I was a bit annoyed to find that it had the exact same rattle.  I was working in the engine compartment one day, and unexpectedly found the source.

The stock B-body has two helmholtz resonators in the intake track.  They are there specifically to cancel intake noise at specific RPMs to help quiet down the car.  You can see them here, they are the big triangle shaped "home plate," and the rectangular "first base" in the lower right corner(pic shamelessly stolen from the internet).

Other than cancel noise, they don't help or hurt performance on an otherwise stock car.  Many, many years ago, I removed the resonators from the Caprice and built a "Home Depot" intake.  It consists of a hockey puck to plug the home plate hole, and replacing first base with PVC pipe.  While I was at it, I put on a K&N filter that I found cheap at a swap meet.  When I got the Impala, I didn't want all my hard work(Ha!) to go to waste so I swapped the intake onto it.

That's how it sat for nearly a decade on the Caprice.  With the hood closed, the filter couldn't really go anywhere, so I never really mounted it.  And that was the problem.  When I would go over bumps, the metal lip of the filter would rattle against the inner fenderwell.  Knowing where the rattle was coming from, I actually decided to do something about it.  Being cheap, I didn't want to have to buy anything.  Then I remembered that I had the factory airbox laying around taking up space.  Out came the sawzall and the grinder..

I hacked away at the airbox lid until the filter fit with the hood closed.  It's only job is to keep the filter from rattling around.  It's not the prettiest, but it works just fine.  You'll notice the AIR system inlet hose isn't really connected anymore too.  That doesn't matter at all because the AIR pump doesn't work on this car anyway.

As a side note, I see people running around with airboxes that are completely sealed from the rest of the engine compartment, many are even insulated.  The reason for this is to keep the intake air as cool as possible because colder, denser air makes more power.  The reality of the situation is this: from reading the intake air temp on a scanner while driving, if the car is moving the intake air temp is only a few degrees higher than ambient air temp.  The air is moving through the intake so fast that it doesn't have time to pick up any heat.  The temp difference is so small you won't see any HP gains, and all the airbox insulation in the world won't make any difference.