68 camaro 383 stoker 2" crowl hood.
car now has a billet specialties 11 7/8 long 8 3/8 wide 2" tall filter.
? Will this draw adequate CFM for a 420HP small block.
It is a nice polished alum,oval shaped cleaner. But is it to small.

According to an article in Hotrod Magazine a couple of years ago, a 14"X2" air cleaner, as seen on most late 60 & early 70 GM performance V8s, flows about 2500cfm. Yours sounds a little smaller but should be good to go.

Fred, do you recall anything about how many inches of mercury it showed at 2500 cfm?

I've always though the minimum to be 14 x 3"

anything less than a 14X4 just looks tiny to me any more.
and the bigger the filter you get, the longer it takes before it needs to be replaced or cleaned.

For looks I like little ones, opens the view.
For maintenance I'm a bigger is better advocate.

I just couldn't believe the 2500cfm claim on a 14 X 2 filter, thats a whole lot of air after all, so I checked K&N's site out and found some interesting info.
First off, the filter they use as a comparison is a 12" X 3.5" filter, the claimed flow of paper is 548 cfm and claimed for the K&N is 881 cfm, a whole lot less then 2500. But then again, it was published in hotrod :D;) .
They actually have an interesting formula to determine what size filter is a minimum for your engines needs, heres the link (http://www.knfilters.com/filter_facts.htm#RESULTS) .Scroll down and you'll see the formula. Of course its a company site and there is some propaganda in the article, but it's interesting none the less.
As for your application, I think 2" is too short, for filter surface area (flow) and also just for a minimum amount of clearance over your carb opening, depending on how your lid is laid out.

68rs 406
Thanks
14 x 3 K&N on order. K&M says it will flow 791Cfm

I hope it fits. 14" dia 3.125 tall net height from flange. with a 7/8 drop.
I do have a 2" crowl hood .500 carb spacer on a dual plane intake. Edelbrock carb.

Jim, I don't recall the test parameters. I'm going to their web site right now to try and find the story. I can't believe these things flow less than 800cfm!
Here's my KN 14X4. It fits inside a stock 2" ducted hood.
http://epitomesrebuild.com/images/241.JPG

From K&N
383 stoker (383 cubic inch)at 6,000 RPM will pull 654CFM
So a 14 x 3 air filter (K&N) will pull up to 791 .


Note this is what they told me.?

Whew! I spent entirely too much time at Hotrod with no luck. Did a google and found K&N's testing procedure. Unless I hurriedly mis-read, they use -1.5" of H2O pressure. That's really high (no suckee) isn't it? Here's the link; http://www.knfilters.com/testmethod.htm
Don't we use something like -20 to -28 or so on heads for flow testing????

Compared to the drop across the carburetor, it's very small.

The bigger the air filter, the slower the air flow through the filter, the better the air is filtered.

Whew! I spent entirely too much time at Hotrod with no luck. Did a google and found K&N's testing procedure. Unless I hurriedly mis-read, they use -1.5" of H2O pressure. That's really high (no suckee) isn't it? Here's the link; http://www.knfilters.com/testmethod.htm
Don't we use something like -20 to -28 or so on heads for flow testing????

1.5 " of water is an air filter that has seen service or is sized close.
Usually a brand new one will read about 0.5" to 0.9 on a fully loaded industrial engine.
Naturally aspirated industrial engines are usually rated at full horsepower with 15" water restriction. And these dudes move some air. About 10 years ago I guess it was a rainy year, and I was on a lark of carrying around this big-ass red umbrella. You don't see too many guys carry an umbrella in the oil field:D, but I didn't give a ****, it was a cool umbrella. I had just started a brand new V-12 and gotten it loaded first time. I thought I heard a noise and I went up beside the compressor to listen, wasn't thinking about my bigass umbrella and the engine's right bank air filter. All of a sudden my umbrella was gone, I was wet, and I heard the engine bog and the left bank turbo spool up just a leeetle more. The Bigass umbrella died. The Bigass engine sped back up after I ripped my umbrella out of the air filter, and it was all I could do to get it out of there. I bet it was pulling about 10 psi differential on that air filter.
:D Haven't wanted another umbrella since:D

Never checked an automotive air filter, but the diesel pickups have filter indicators similar to industrial engines. Some of the industrial ones are even scaled in inches of water.

Edelbrock port flow's their heads at 28" of water fwiw

Thanks for that Tim. Yet another reminder of the vast variation of experience, knowledge and talent on the board.

One nice thing about using a 14" air filter is if you feel the need for more air flow you can top the filter off with one of the K & N X-Stream tops. They have many different styles out and don't add to clearance problems.

One nice thing about using a 14" air filter is if you feel the need for more air flow you can top the filter off with one of the K & N X-Stream tops. They have many different styles out and don't add to clearance problems.
if you are having hood clearance issues, then i don't think one of those X-stream lids will do much good, since it will be right up against the bottom of the hood.

if you are having hood clearance issues, then i don't think one of those X-stream lids will do much good, since it will be right up against the bottom of the hood.

I ordered two from summit (I will return one) One is a K&N 14" X 2" round with a x-stream lid. The lid . Lid alone pulls over 500cfm . It should be plenty. The other is a summit 15x8 oval x 2' thick also a x-stream type.
I will keep what ever one looks and fits the best. They both draw more cfm then a 383 Cubic inch small block @6k rpm. the 2" thick will be fine 3" ? may hit. But the x-stream lid makes up for it.

Good Idea skar.