Hi everybody ! Last night after putting my car together and driving it for 20 minutes i threw the bearing now i need to ebuild my block but i tryna figure out what was it i would appreciate any advice !! here the deal :
B18b1 engine 95 Integra SE stock but 4-2-1 headers some exhaust and short intake i was driving with bad headgasket for year or so finally found time to change it thinking my head is not good i bought a head from HT member here send it to machine shop got the valve job done otherwise they said the head was fine Its the p75 head my old one is pr4y so i changed HG TB WP all the gaskets etc . Started the car everything was fine drove it down the block for 10 mins Oil pressure light came on i drove it back to the garage it made it shut it off checked everything started it again light came on again i pushed the gas pedal it started flickering so i thought its bad oil sensor put my oil pressure gauge read oil pressure is 0 hmm anyways drove it gain i heard this familiar noise the bearing makes boom my block is done !!!!
So i dunno what the problem is the car was fine before with my old head just the hg neded to be changed i think :
1.my old head was pr4y this one is p75 has better flow so it put more pressure on my old bearings and my block
2.there was a crack in the head so it didn't build the pressure (machine's shop fault)
3.could the cams be the problem so it didn't build the oil pressure ?

Does anybody has the same problem before ! I could use some help before i start rebuilding my block don't want this happen again ! I don't have much time and i need the car running soon !

Thank You!