To burn heavy fuels like distillate efficiently, old tractors featured special heat-exchanger intake manifolds. Exposing the intake mixture to hot engine exhaust vaporized heavy liquid fuel droplets before they entered combustion chambers. This smart thermal engineering prevented fuel pooling, minimized oil dilution, and ensured smooth combustion during cold weather field operations a... https://www.chiguu.com/articles/what-is-your-old-tractor-actually-worth-complete-farmer-guide