Small Block & Big Block Chevy Specific - why would this happen?....

ok...this all started after i had a bad tank of gas...i could not get this car to run ok after this tank even after 3 refill tanks and a plug change...the car kept missing at idle but ran ok above 3000rpms...i was on my way back from madison wiscosnin (i live in green bay) the motor decided to puke all over the highway at 70mph....i found what seemed like a huge hole in the block and figured a rod let loose....when when i got it home number 2 was in half but still connected to the crank with one missing bolt in the cap...ok....but why the hole in the block.....when we pulled the heads and investigated more i found the timing chain gear (big top one) fall completely out of the block with the front of the camshaft...i have never seen that before...a little more digging i pulled out another chunk of the cam and there still is a bigger piece still inside the block....wtf.....so what could have caused this...i dont think bad gas would have this to tear apart a motor to this degree or am i wrong?.....otherwise the car ran perfect until that tank of gas...all for the better because she is getting a 6liter/6spd :)...

http://img.photobucket.com/albums/v291/bluecamaro/IMG_0047.jpg
http://img.photobucket.com/albums/v291/bluecamaro/IMG_0045.jpg
http://img.photobucket.com/albums/v291/bluecamaro/IMG_0043.jpg
http://img.photobucket.com/albums/v291/bluecamaro/IMG_0042.jpg
http://img.photobucket.com/albums/v291/bluecamaro/IMG_0052.jpg

any guesses?

The bad gas is probably pure coincidence. It looks to me like an over rev condition caused a catastrophic internal failure. There is a car club here in So.Cal. called "the cambusters", it is an elite club, because in order to be a member, you must have busted a cam, and it takes alot of abuse to bust a cam. Deffinately a high rpm failure, it takes a certain amount of force to do that kind of damage, and that force can only be created by extreme pressures.

I snapped a crank from having a bad vibration.Maybe you had a vibration issue,that would explain all the bolts that fell out.

My theory is that the bad fuel caused detonation which cracked a piston, the piston came apart and left the rod there swinging around to hit anything. It's very common to see a hole in the block and a broken cam when a piston lets go even if it's just the bottom of the piston.

My theory is that the bad fuel caused detonation which cracked a piston, the piston came apart and left the rod there swinging around to hit anything. It's very common to see a hole in the block and a broken cam when a piston lets go even if it's just the bottom of the piston.

Coulden't have been the piston it was still connected to the rod the rod did all the damage. Was any of the bolt in the rod or just laying in the pan. and detonation probably did this it causes severe vibrations and pressure on the rotating assy. You have to realize that there is only a couple of thounds of an inch clearance between the block and the rods and cam. when one thing lets loose all hell breaks loose.

its really hard to tell from just pictures and not being there.. but u say the rod was still attached to the crank but the cam broke .. so i am assuming part of the cam fell down in the motor and got lodged between the rod and the bottom of the cylinder wall and took it out and the block .. .hard to say,

The remains of #2 rod, still attached to crank, collided with the cam and broke it. Hence the timing gear falling off.

Chances are you mistook the erratic running of a dying engine for bad gas.

Coulden't have been the piston it was still connected to the rod the rod did all the damage. Was any of the bolt in the rod or just laying in the pan. and detonation probably did this it causes severe vibrations and pressure on the rotating assy. You have to realize that there is only a couple of thounds of an inch clearance between the block and the rods and cam. when one thing lets loose all hell breaks loose.
LOOK AT PICTURES ONE AND FOUR. THE ROD IS NOT CONNECTED TO #2 PISTON LOOK HOW the piston is rotated in the bore!!

I had a piston rotate in a bore and the rod was still connected. The rod was bent pretty badly though. Looked crunched down like a spring or something.