I recently picked up a 72 Valiant sedan with a 225 3spd auto with 80k I am new to these cars and don't know much about them, but this car has been my daily driver for the past month now and I've put just a little over 2,700 on it since I started driving it. The car has been nothing but reliable until this week when I noticed a pretty large crack in my exhaust manifold right before leaving school on the ride back to my apartment I was pulling off the exit ramp and went to go give it some gas and the car sputtered and stalled so I pulled off to the side and tried to crank it it turned but then sputtered and stalled again. Right after that a huge puff of white smoke came out from under the hood, the top radiator hose blew.after I got it towed back to my apartment I went out and bought a new hose and thermostat replaced both filled up the coolant again bled the system and cranked it over again, it would hesitate when I gave it gas then I noticed a little knocking coming from the engine I can't pinpoint the knock but it is a very subtle knock. I continued to let the car run at idle and noticed the temp gauge kept climbing. I turned it off and let it sit and when back out after it had time to cool down and cranked it again and it started right up no problem I let it warm up again and gave it a quick little rev and noticed a little smoke come out of the exhaust so I tapped the gas again and the motor made a very strange noise it popped and then calmed down and was running a little better then stalled and now it won't crank at all, you can see the pulleys trying to move when you turn the key, also if you hold the key for more then two seconds it starts to smoke off the negative ground on the battery. If anyone has any input please let me know all help is welcome.

First step based on the 'no moving when cranked' and some symptoms of what may be a blown head gasket or internal water jacket crack:

I would pull all the plugs and look for water/coolant on them. The object is to see if there is coolant in a one or more cylinders. (NG at all). Then see if the starter will turn the engine over with all the plugs out and look for water/coolant being pushed out of one of the holes.

Thank you for the info I'll look into that. Would you have any idea on the knocking though? Or if it could maybe just from the crack in the manifold? Do you think the overheating could be caused from the carb running too lean as well? This is my first carbeurated car so this is all kind of new to me.

Welcome to the board. Unfortunately, this what you describe probably adds up to very bad news: coolant entering a cylinder can really ruin an engine. It's a condition called "hydraulic lock" or "hydrolock". Liquid is not compressible (this is why your brakes work), so when it enters the cylinder and the piston comes up, it runs smack into a hard, uncompressible barrier. Unless you're very fortunate, the connecting rod(s) in the affected cylinder(s) bends even though it's made out of very strong metal. The fix for this condition is a complete engine rebuild or swap.

However, don't assume this worst-case scenario is what has happened to your engine. If the liquid entered the cylinder while the engine wasn't running and the water-smack occurred during attempted cranking, there's a pretty good chance of no hard-part damage. However, a thorough and careful engine clean-out will be necessary as part of the repairs, because coolant will have got in the crankcase and mixed with the oil, which forms a very nasty sludge.

Whether you'll be doing the work on this car yourself or getting pro help, as quickly as you can get the three books described in this thread. Actually you don't need to buy the factory service manual; you can download it free of charge here. But get the other two books in a hurry to get you up to speed on the technology and put-together (and take-apart, and fix) of your car.

A cracked exhaust manifold can indeed sound like a knock, and it can also mask other noises so they sound different than they actually are.

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