Right, air filters….
I had been musing over this subject for a long time. My first thought was to get a custom 3D printed air box made, second was use an off the shelf air box married with cone filter, large oval filter or foam type filter body with custom base plate. I am a fan of K&N filters after seeing/reading an article by David Vizard on them, so was keen to use their filters.
In the end I plumbed for dual K&N DCNF individual filter units. The only problem being they do not sell them anymore…… So a quick EBay search revealed a guy selling a pair which were on a Capri(?), no idea which one, but anyway they were what I needed. I thought it would be a straight forward job to then just fit them, how wrong could I be.
First up, the cutout on the filter for the DCNF is for the original carb, the Jenvey throttle body has the same mounting holes, but the area around it is smaller, so there are gaps, not so useful for an air filter. So a filler plate needs to be made. As well as this the two filter housings are a few mm too wide to mount next to each other, so each one would need the mounting holes moved approx 1cm to allow them to fit side by side. I ordered some stainless sheet and started to make one, then realised my second problem, the butterfly spindle arm on the throttle body which attaches to the accelerator cable protrudes above the height of the throttle body which means this arm interferes with the base of the air filter housing.
So we are now needing a 10mm spacer instead of a simple plate. I ordered a pair of high temp nylon sheets and set to drilling the spacer. That was when I hit the last problem which I had completely missed as the throttle bodies are new and not made up. Attached to the throttle body are the two injectors and a fuel rail above the injectors. This all protrudes well above the top of the throttle body and hence the air filter body and spacer have to not only be moved to separate the two filter housings, but also have to be offset from the fuel rail. I had already drilled one spacer and the two housings before I realised this, so another spacer sheet was ordered and more holes put into the base of the filter housings. As the housing had been moved so far from the normal position a fair amount of metal removal was necessary to remove obstruction from the inlets. The final spacers were drilled and the inlets shaped slightly to avoid a sharp edge. The end result is not so pretty, but should be functional.
All this took an age to do, satisfying in the end, frustrating at times. To finish off the job I ordered some stainless fixing bolts and for the top of the filter housings, knurled stainless nuts as the ones they came with them were not so pretty…
I am aiming to baffle the hot air from radiator away from the filters and also baffle the cold air towards them when I get to installing the engine bay parts.
Photo is of one of the filter housings modified with spacer plate.