what the heck happened

whe i was younger in the mid 80s one of my first jobs was working on a salvage production line.
my job was to check and certify used engines. they would come down chain line,sealed and plugged and then put in what i would call a giant washing machine. you could put 2 v8 engines and trannys in it to be washed!!.
they would come out clean as when new.
my job was then to get them running and check oil pressure,compression ,minor teardown etc certify them for warranty rating paint them up and way they go . kind of a neat job.
i had a 305 with a banks turbo kit come in one time and was kind of excited to check it out. thought this thing would zing pretty good.
got it on the bench hooked up and it wouldnt fire or run. things were always wet and tough to start because of the wash. we had a buzz box made out of a ford ign and a modified hei dist cap that we would put on the stubborn ones, that thing would throw a 11/2 inch spark and would start almost anything.
well i got this thing ont he motor and was pumping the accelerator pump to get it going. it had fuel ,spark sputtered a few times and boom!!!!
the whole engine blew up both valve covers were torn off the oil pan was balooned out . we never did find the dipstick unti a week later, it was stuck like a arrow in the insulation in the ceiling 30 ft above us .
i had been hanging kind of over the motor at that time. couldnt hear for a while after. it was like a bomb.
took that motor and wheeled the entire unit to the junker core pile.
a guy from work bought it for 150.00 resealed it and put it in his street rod it ran fine.

what the heck would have happened to cause a oil pan explosion of that magnitiude in a motor?
my only thought was after the accident that the car had previosly been in the carb drained fuel down into the oilpan and whan it was washed(the temp was 160 degrees) it heated the whole unit up and was full of fuel vapor and somehow i lit it off.
i have never seen a motor have that kind of internal explosion .
anybody out there have any thoughts.:D :D :D

It probably didn't have a working pvc valve. a backfire in the intake manifole and the fire traveled thru the pvc breather lines to the crankcase KABOOM i have seen them puff out the oil pan and valve covers

that makes sense, i can still remember the older fellow who worked beside me. he was under his bench when i got up off the floor .

you had pumped some raw gas into the pan and then sparked an arc.. thats makes a bomb. thats why you dont weld on oil pans. :CRY:

Back when I started in the "business", I pumped gas for a guy that worked on and sold Mopars - '35 Plymoth, '57 Savoy, '52 Desoto, etc. One day they had a 331 Hemi in an old Desoto that wouldn't start - gap the points, move the timming, etc., etc., Shoot the carb with either. Just as I walked past the front of the car someone keyed the ignition and POW, a backfire and a ball of flame came rolling out from under the hood. You didn't need to look far for me - I was under the workbench waiting for a "safe" time to come out.