Most of the products sold as an anti-fowl device for old worn oil burning engines have the metric threads of later type spark plugs and they are straight bushings. Having a pipe thread, the model T plugs could be adapted with any pipe thread bushing that had the correct threads that would fit. The person that decided to use 45 degree pipe elbows may have felt that turning the plug a bit would allow a more unshrouded spark to ignite the F/A mix. Folks got pretty creative to keep their old flivers running longer before having to spend money on an overhaul.