K&N Air Filter Assembly Custom Lids and Tops Billet Aluminum Spoked Lids A recent addition to our Custom 66 Series™, these 14” assemblies feature a billet aluminum spoked lid with a carbon fiber insert.  Both fit 5 1/8” carburetor flanges.  Full assemblies shown on Custom 66 page. 10 Spoke Design P/N 85-6850 5 Spoke Design P/N 85-6848 XStream® Chevy & GMC Replacement Lid Improve airflow and appearance on your late model Chevrolet-GMC truck and 1968 to 1995 GM vehicles with one of our new XStream® air cleaner lids. They come finished with a deep luster chrome or black with our XStream® Air Flow Top built in! These direct replacement lids are an inexpensive way to dress up your engine compartment and increase your airflow. Chrome Air Filter Top: 66-1201 Black Air Filter Top: 66-1202 K&N has taken advantage of the lightness, strength and durability of carbon fiber to bring you our Carbon Fiber Lid. This new lid combines all the necessary features for racing with the good looks only carbon fiber can provide.

This top lid fits K&N air filters part numbers E-3740, E-1650, E-3743, E-3745, E-3730, E-3750, E-3732, E-3760, E-3770 or any round air filter with an 14" outside diameter. At 4.6 oz this lid weighs 1/4 as much as our standard chrome top plate. 14" O.D. top plate Carbon fiber (center rises 1")……… 14" Drop Base Plate K&N's 14" air filter drop base plate is available separately for replacement or special applications. Base plate fits carburetors with 5-1/8" airhorn flange. This drop base will clear electric choke mechanisms. 14" O.D. drop base, Chrome plated steel, 5-1/8" flange (drops filter 7/8" below carb flange)……… K&N P/N Complete Assembly 14" Offset Flat Base Plate K&N's 14" air filter offset flat base plate is available separately for replacement or special applications. Base plate is offset 1-1/2" and fits carburetors with 5-1/8" airhorn flange. 14" O.D. offset flat base, Chrome plated steel, 5-1/8" flange (sets filter 1-1/2" off carb flange) 85-3540

9" Metal Base Plate 9" O.D. base, Pollished Stainless steel, 7-5/16" flange - 03365 Custom Air Filter Plates K&N's 14" air filter plates are available separately for replacement or special applications. Knight Window CleaningBase plates fit carburetors with 5-1/8" or 7-5/16" airhorn flange. Nursing Home Patio FurnitureDrop base will not clear all electric choke mechanisms, it may be necessary to space up base plate with a locally available air cleaner spacer.Top Rated Hot Tubs Consumer Reports 14" O.D. drop base Chrome plated steel, 5-1/8" flange (drops filter 7/8" below carb flange) (drops filter 1-1/4" below carb flange) 14" O.D. flat base (raises filter 9/16" above carb flange) Nylon reinforced plastic, 7-5/16" flange

(raises filter 3/4" above carb flange) 14" O.D. offset flat base, Chrome plated steel, 5 1/8" flange (sets filter 1 1/2" off carb flange) 14" O.D. top plate (center rises 1", stamped with K&N logo) Improve the overall appearance of the engine compartment on your late model Chevrolet-GMC truck and 1968 to 1992 GM vehicles with one of our new chrome air cleaner lids. Each lid comes in a deep luster chrome embossed with the K&N logo. direct replacement lids are an inexpensive way to dress up your engine compartment without disturbing emission control equipment. separately or packaged with an E-1500 filter element to make a complete Pickup (w/single wing nut) V8 Complete Kit With Chrome Top Lid and Replacement Filter (E-1500) 68-92 GM vehicles using 12" o.d. x 3-1/2" h. filter (E-1500) Complete Kit W/Chrome Top Lid and Replacement Filter Chrome Top Lid Only (see CE-1501) 93-95 Chevy/GMC Pickup (w/dual

wing nuts) V8 Complete Kit With Chrome Top Lid Only (see CE-1502) 68-95 Chevy/GMC XStream Flow Top Lid These filters are legal ONLY for racing vehicles.  Not applicable, nor intended for use on emission controlled street or highway vehicles.If the devil is in the details, then he’s certainly lurking around the carburetor on your thumper big-block. Horsepower and torque are all about moving air into an engine, especially on the way to the 500-plus horsepower level. The fact is that any engine, even the lowliest lawn-mower motor, can benefit from improved airflow management.While we know better, many car crafters consider an air cleaner as more of a nuisance than a power asset. But today, when 400 to 500 hp is relatively easy to achieve, the engine is moving a tremendous amount of air. So we thought it would be a good idea to pay closer attention to the air cleaner design and test a few parts to see if there is power to be gained.We could have tested with a 400hp small-block, but frankly significant power differentials may have been more difficult to achieve.

So instead, we went with a GM Performance Parts 454 H.O. engine equipped with a set of World Products Merlin Jenkins iron heads and a healthy mechanical camshaft (see Engine Specs) with a matching Merlin single-plane intake and a Holley 750-cfm 0-4779 mechanical secondary carburetor. On the baseline test, this Rat proved it was no slouch, delivering a solid 567 hp at 6,200 rpm.Our test outline was simple. We baselined the engine without an air cleaner, then tested a 14×3-inch air cleaner assembly with a flat base, then went to a Stub Stack without an air cleaner, and then tested one of K&N’s Flow Control air cleaner assemblies. The test of the 14×3-inch air cleaner assembly is not in our test results since it made the same power as the baseline (with no air cleaner), which meant that the standard air cleaner assembly did not cost any power. Overall, our 570hp Rat motor responded with more horsepower on virtually all these different tests. The best combination for this particular big-block engine configuration proved to be a 14×4-inch K&N air filter with a Stub Stack along with an XStream airflow top.

This combination of K&N filter parts was worth a solid 14 hp over the “no air cleaner” baseline. It’s important to mention that this combination made the best peak power, but comparing the average power between Test 3 and 4 revealed very similar results.An important point (which K&N offers in its instruction sheet with the Flow Control air cleaner assembly) is that if your engine is tuned to its best lean-power combination, adding the Flow Control or any other welldesigned air cleaner assembly will require increased jetting to compensate for the increased airflow and better air quality across the top of the air cleaner. Our test big-block actually recorded slightly rich air-fuel ratio mixtures at peak power with just the bare carburetor. Once we added the Flow Control and other air cleaner assemblies, the additional airflow slightly leaned the air-fuel ratio by roughly a quarter of a ratio. This probably improved the power slightly, although earlier jet changes of more than half a ratio did not improve the power output more than a couple of horsepower.

Also interesting is that Westech’s Steve Brule mentioned that on previous dyno tests with the XStream Air Flow Top that it seems to work best when combined with flat-base air cleaner assemblies. Conversely, he has seen a slight power loss when the same lid is combined with drop-base air filter assemblies. We did not test a drop-base air filter assembly to verify this point.At the very end of our test, just for fun, we tried a small 9-inch-diameter air cleaner assembly equipped with a 2-inch-tall paper air filter element, which cost 35 hp over the best combination. This is an indication of what can occur when you do not pay attention to little details like air cleaners and filter elements when building your fast street car.We learned that paying attention to air cleaner design and especially to how air enters the carburetor can pay huge horsepower benefits as power numbers continue to climb. The overall key appears to be ensuring sufficient space above the carburetor to allow air to enter the carb (or throttle-body) without creating turbulence that can cause power to suffer.

It appears that maintaining roughly a 2- to 3-inch clearance above the top of the carburetor is a great way to offer your engine every opportunity to make power. This is not always possible with low hood levels and tight engine compartments. But the fact remains that should you choose to restrict the inlet air into your engine, then you can expect to lose power as a result of that compromise. It doesn’t get any simpler than that. Another way to look at this is with a simple question. How much money would you expect to pay to make an additional 14 hp?Air cleaner assemblies or air filters don’t make power, but the right combination of airflow-enhancing filter assemblies will help your engine make all the power it is capable of producing–and keeping that horsepower-devouring devil out of your details.Test 1 Baseline with no air cleaner, 0-4779 750-cfm Holley w/chokeTest 2 Flat base w/14×4-inch K&N filter and Flow TopTest 3 K&N Flow Control air cleaner w/14×4-inch filterTest 4 Flat base, 14×4-inch filter, Stub Stack, and Flow TopTest 5 9-inch-diameter, 2-inch-tall air cleaner w/paper filter