Holley carb to air filter top clearance?

Ant · #1 (**permalink**) 07-21-2006, 03:38 AM

With running a Nascar style manifold and Pro-systems Holley on my 9.2" deck height, Yates 373 engine, I am having to fit a larger hood scoop and fabricate a dropped air filter base. I have worked out minimum air filter required for me to run 7500rpms is a 16" x 3" K&N or suchlike, but I am going to have to go to about 2 - 3" on the dropped base, so I am unsure of how the air flow likes going over the carb from underneath instead of in the side and just doing a 90 degree turn, underneath probably is 120 degree suchlike turn!

Further to this problem, due to this high manifold I can only really utilise a 1/2" heat spacer under the carb, room for an air filter is 2" above the air filter flange, and that will necessitate me to shorten and angle the two bowl air pipes that sit up about 1" on top, or plumb tubes from them.

Then the post question, a carb that flows up to 950cfm (actual 750cfm) must need a minumum clearance above the filter flange/venturi's to top of filter?

WV66AC · #2 (**permalink**) 07-21-2006, 04:07 AM

I have a 1 7/8" dropped base -- probably off an old corvette. If there are others with more drop -- I have not seen them. K & N makes filter "tops" as well to allow breathing through the top. Good luck.

Ant · #3 (**permalink**) 07-21-2006, 05:36 AM

WV66AC,

Thanks, have looked at the K&N X Stream Tops, have heard some not so good opinions on those, maybe there is less restriction but flow issues!

I will make my own dropped base due to air scoop allowing 12" width, up to 18" length, and I guess you need an 1" around the filter for it to work!

Rick Parker · #4 (**permalink**) 07-22-2006, 07:19 PM

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One of the topics that is not discussed much is how the air actually passes through the filtermedia and then has to flow up and over the choke tower that is left on many of the Holley in single and dual 4 Barrel applications. It impedes airflow considerably. If you decide to use the the drop type filter housing which works very well, eliminate the choke tower, or use a HP type Holley or Race Demon. They all improve airflow dramatically.

Morris · #5 (**permalink**) 07-23-2006, 06:51 AM

Ant

http://www.universalspinners.com/autoparts.html

Check this out..... Allen (Ironworks) gave me this lead and we had discussions with Michael....and we came up with a soloution.....for a Dominator carb.... 7 5/16" opening.....

The height above the carb is about 2" with a nice bell entry to the carb ..

We went to a 16" filter and a 14" Extreme Top with an adapter for the 14" top to the air filter...... and a 2" dropped base....

Flow is good ....and in excess of 1200 cfm ...and will come from our reverse hood scoop..... back of hood....

Best soloution we have found yet...

Morris