I'm working on my first engine build, and trying to figure out what air cleaner to use. I'm looking at K&N x-stream assemblies (14 inch). The engine will be a 496, and I'm planning on using a RPM Air gap manifold with a stock SS hood (on a '70 Chevelle). Anyone know what size filter I can get away with? Is it better to use a raised base with a shorter element, or a dropped base and taller element? I'm new to all this, so forgive me if that's a stupid question. In my thinking, the dropped base would be better, as I don't think the airflow from the lid would help much if the lid is too close to the hood. Am I wrong? Thanks for any insights.

Go with a drop base right from the start.....at minimum you'll be able to run a 3"......

I have a 454, RPM Air Gap, one-inch spacer under carb, and I use a 3" drop base air cleaner. It all fits under my SS hood. I think I have about one inch to spare.

Thanks, I really appreciate the responses. This site is great.

Even with an RPM intake,you can easily fit a 6" tall filter with a drop base.

I have a complete functional CI hood on the 70, which NORMALLY comes with a 3x14in air filter and I have a 4x14 filter with room to spare. I think I could go with a 5x14, but there is no such thing as a 5x14. The next size is 6x14, and that may touch the hood.

Tom, K&N sells a 5" filter. I have one on my El camino.
http://store.summitracing.com/egnsearch.asp?N=700+4294925239+4294925170+42949251 69+400171+4294891681+4294791516+115+4294791515
Summit has 13 listed on their website.
http://store.summitracing.com/egnsearch.asp?N=700+4294925239+4294925170+42949251 69+4294891681+4294791516+4294791515+115

I have a 5" K&N I've had on mine for a short time, it fits fine - but I backed off to the 4" because the taller one looks a little odd with the hood up.