Cox engines with fuel tanks
Depending on nitro content of fuel, it's been my experience that 15%nitro/castor will yield something like this...
Texaco - 4 to 5.5 minute run... 5 fin glo-head, 8cc tank(no vent) small venturi, dual transfer, twin slit exhaust ports.
Baby Bee - 2.5 to 3.5 minute run, 4 different cylinder types, single transfer/single exhaust, single tranfer/dual exhaust (large), dual transfer/twin slit exhaust, metal or plastic backplate
Golden Bee and Black Widow are the same engine ( at least mine are ) 2.5 to 3= minute run, stunt tank, larger venturi than Baby Bee or Texaco
Venom - 2.5 to 3 minute run if your lucky
Killer Bee - 8cc of fuel, avrg 2.5 minute run
Note: the Venom and Killer Bee ( pre-Estes ) had the high performance "Bullit" crankshaft ( drilled crankpin,scalloped and lightened counterweight )
They all run better with higher nitro fuels...