Since I put the blower on my 78 Malibu I've got hood clearance problems, even with the 2 1/2" cowl hood. So low profile air cleaners have become a necessity. My old 14x3" drop base open element just wouldn't clear. So I decided to contiue to use the drop base, put in a 2 1/4" element and a K&N Xtreme flow lid. The idea being that what I lost in filter area would be more than made up for by the flow-through lid. Good plan, I thought.

Then I got the parts and put it togehter. I knew I was in trouble right from the start. It all fit together, went on top of the carb, and fit under the hood. However, the Xtreme lid, while EXTERNALLY idetical to a regular solid lid, is INTERNALLY very different. The pleats of the filter stick down inside the air cleaner about 3/4". Putting it very close to the top of the carb. Too close in my case.

First time out I knew something was wrong. Picked up a stumble as I laid into the primaries that wasn't there before followed by a long bog. I disconnected the secondary linkage to confirm the problem was on the primary side. It was. I played around with the jetting and accelerator pump for a few hours with no improvement whatsoever.

Acting on my hunch I took off the Xtreme lid and put the plain sheet metal lid back on. Problem solved. 100% totally fixed. All from just getting the air cleaner lid 3/4" higher off the top of the carb!

Moral of the story- beware using the K&N Xtreme Flow filter lid with a low profile air cleaner. FLow isn't everything! The carb just needs ROOM above it to allow the air to enter the venturis in a clean and unobstructed way or it won't meter fuel correctly.

 

I've been preaching against drop bases whereever you can get away with it for that very reason. However, I wonder if that lid wasn't sucking right down on top of the bores and plugging things up, causing the problem.