Greg:
I have not looked at the mounting flange of a FL-1A in quite some time. However I will agree that the little oval holes in the FL-1A may provide more flow, however it is the materials that the filter is made of and perhaps some internal differences that make it and a select few others preferable if pressures or pump volumes have been increased. That being said, I do not currently use one due to size constraints. Because of poor planning on my part, when I changed the slave cylinder setup on my car it unhappily necessitated a shorter filter, consequently I use a K&N #2003 that is between a Motorcraft FL-300 an FL-1A. Through my "exhaustive research" (opening boxes at the speed shop
) it is the only one of it's size, and the longest that will fit in the area that I have the filter in, even though the thread sizing is 13/16" instead of the 3/4" that is OEM Ford. I am a true believer in a large filter and really fight with the idea of a small filter on an engine that has increase flows with a higher volume pump. The high volume pump for a 289/302 has the same gerotors in the pump as that of a stock 351W. However in many OEM applications for the 351W even with the Police Package, they were content to use a FL-300 (shorty), this was often dictated by chassis constraints too. If you want a frighening comparison check the filter size on the current GM V8 offerings, they look like they should be on a Honda! Old ideas die hard around here.
This during the redo and prior to finding the K&N.
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