K&N open element air filter

In the US, if you try to use the K&N vehicle search function to find an air filter for your 1978-80 Fiesta, you will be steered towards a filter that fits in the stock air box.  And that filter works great on a stock carb.   If however you have modified your engine with a head, exhaust, carb and or intake, or you just want an open element air filter, you will need to select a 1981-1986 Fiesta XR2 as your vehicle to return the Open element filter parts that fit the DFT style of carb.

I installed the open element K&N filter kit on the larger Weber DFT9a 32/34 carburetor. This has the same top pattern as the stock carb.  This made a very big difference in throttle response through the power band.  In fact it eliminated all sluggishness left in the car.

The stock oil filler cap has the PCV valve in the neck of the cap, however you will need a vacuum source on the top most hose.  This connects to dirty side of the stock airbox through a 5/8" connector that has been clipped into a hole in the side of the box.  There is a small mat of fiber that looks like it collects any oil droplets that get sucked past the pcv valve, and drains it back down the hose to the filler neck.  We are probably not going to be able to get that fancy with the filter kit.


Project Parts List
Filter Assy:
56-9015 - Custom Racing Assembly (stock or lower Engine)
Or
56-1730 - Custom Racing Assembly (Lowered Engine)


PCV Vent Kit
85-1190 - Plastic elbow 5/8" (clean side of filter, Drill hole in bottom plate of filter kit to fit)
OR
85-1362 - Metal Marine Style 5/8"x2.75 tall (Dirty Side of filter - not sure if you will get the suction required with this set up, and you will need to trim to fit the 56-9015 kit.  Use 85-1462 with kit 56-1730, you will need to trim to fit)
OR
Drill a hole in the bottom plate 2mm smaller than the OD of your hose and simply stuff it in there.

You will also need a new length of hose for the PCV connection to the filler cap.

I used the 56-9015 Kit.  The best price I found was on eBay from Summit Racing.  It was cheap and shipping was free.