One problem I have is ensuring adequate air flow to the Holley carb with a very small bonnet clearance. The previous owner actually punched holes in the existing foam filter as when on a rolling road he was told the filter was restricting the engine. This obviously ruined its filtration ability though! The question was how to accurately measure the clearance as the bonnet slopes and is not flat! I have been to some childrens parties recently with crisps, cake, the token sandwiches nobody eats anyway and lots of nibbles on cocktail sticks, whereupon I hit upon an idea I shall call the "Birthday party cake method". It sounds crazy but it works really well. It beats peering through one of the bonnet louvres with an old cystoscope (meant for bladder examinations) which was my original not-so-great plan.
1) I was wanting to use a US style 14inch pancake filter. The question was, what was the maximum depth of circular filter could I get to fit under my bonnet? 2) Using a deep downward dished baseplate clamped temporarily in place (Pipercross), I made a cardboard air filter replica matching the minimum possible depth filter I could potentially buy (2inches deep). You could make the whole thing out of cardboard I suppose, just has to be well fixed in place. 3) Into the top I stuck a ring of cocktail sticks (left over from said parties) so they all stuck out about 2 inches further from the top of the replica air filter. At this point it looks a bit like a birthday cake with candles on it.
4) This is the best bit - cross fingers and slam the bonnet shut! 5) Open the bonnet and, assuming they have not all bent or snapped, the cocktail sticks will have been pushed back into the top of the cardboard filter by different amounts. 6) The amount they are now sticking out replicates the underside shape of the bonnet above the air filter. 7) Measure everything over and over again, then get on the phone to V8Tuner Ltd and order, in my case, a 2.5inch circular K and N filter.