Exhaust Fire

well, my dads Bronco has a problem. Whenever my dad dry revs his Bronco to about 3500 RPM, it shoots out about 2-3 feet of fire. NO SPARKPLUGS IN EXHAUST. There is a possible leak. Please help...

This is a Carbuerated Engine? I'd cut the gas supply to nearly half...maybe check the timing..?

Maybe check the o-rings? They're on top of the engine, under the fuel injectors. They're what keeps the injectors in the manifold...maybe some leakage there. (O-rings are just plastic/rubber bands. They don't make news when you put them on, but they make news when they go bad.)

Does the 5.8L 'tick' when it runs? If so, maybe the head valves need cleaning, resurfacing, replacement, re-angle-ing.