I recently ordered a new custom built Quick Fuel carb and the fellow asked me about my air filter size. He told me that the stock filter setup just wouldn't flow enough for my particular engine so I set about trying to remedy that.Tomaselli wrote:BlackDog wrote:I'd like to be running the taller K&N filter ( can't remember the # ) that fits the stock housing
I did some work on various thickness of the K&N Filter that will fit the "factory" air filter housing; the first I have listed below (1.5in depth) is equivalent to the standard setup. The others are available from a UK Tiger parts specialist who is a recognized agent. Clearly, clearance issues will be a consideration depending on what carb/inlet manifold you are running.
Fron K&N technical desk, I also got the CFM flow ratings and have listed these also, as it will be a consideration for some of the "big carb" brigade
E-2859: approx. (1.5in), 381CFM @ 1.5” of water
E-3710: approx. (2.0in), 508CFM @ 1.5” of water
E-3717: approx. (2.5in), 638CFM @ 1.5” of water
E-3720: approx. (2.75in),699CFM @ 1.5” of water
E-3723: approx. (3in), 763CFM @ 1.5” of water
I ordered an E-3710 and was surprised that it isn't actually the same diameter as the stock one... It's curious that K&N list all 5 with the same dimensions ( except height ). I'd say the E-3710 is at least 5/8" smaller in circumference... doesn't sound like much but if you fit it nicely on one end, the other has at least 1/4" gap all around the curve ...
I don't have room to just throw in the new element as I only have 3/8" clearance ( RPM 'Air Gap' manifold, no carb spacer) to the underside of the hood ( bonnet) but by virtue of using the dual fuel bowl 'Holley style' carb there is room to lower the bottom plate of the air cleaner. It would be easiest to just cut the riser off the bottom plate but with the value of original parts, that wasn't an option !!
I made a new bottom plate that was dead flat off of the flange without too much difficulty and managed to get it fit between the fuel bowl level adjusters...
The GOOD news is I now have a 2" high element and the top of the air cleaner assembly sits just a tic over 1/8" above where it used to be !!
I believe that the CFM gains are at LEAST what was quoted above... if you measure the actual filter part height... on the stock filter, there is about 15/16" of element showing and on the 2" unit there is about 1 7/16" which is a full 50% increase in area !!