Barracuda - 318 Small Block, Won't idle,

[cogaussie]

I was starting my 72 Barracuda 318 from cold, when I heard a bit of rattling (like a spring came loose) Then I noticed it was running very rough and would not idle.

I pulled all the spark plugs and noticed one of them is rather damaged...

Photos attached.

 

[Chryco Psycho]

Something must have been dropped into the carb & Got past the valve into the engine , you can use a boroscope to look inside but I suggest you need to pull the head off

 

[Challenger RTA]

An other option would be to remove rocker shafts. Do a leak down test if you have one.
In general with a cold engine it might determine possible issue before you get there. And fix other thing while your in there. Intake or exhaust valves or ring condition. You more than likely need to remove the head as said. Good luck.

Cylinder Leak-Down Tester Leakage Leak Detector Engine Compression Tester Gauges | eBay

 

[Xcudame]

I agree, time to take the head off and see what happened. You might be looking at complete rebuild depending on damage.

 

[cogaussie]

Ate a valve head

 

[Xcudame]

And that piston has a couple big cracks. Probably being held together by the rings and cylinder block. Is this the numbers matching 318? If so, I'd rebuild it - keep the Barracuda original. Just make sure the cylinder head and block are checked for cracks. If it's not the original 318, I'd spend my money on a 360. 360 long blocks are still easy to find. Or get a short block and run aluminium heads. All depends on your budget.

 

[JKCuda]

And that piston has a couple big cracks. Probably being held together by the rings and cylinder block. Is this the numbers matching 318? If so, I'd rebuild it - keep the Barracuda original. Just make sure the cylinder head and block are checked for cracks. If it's not the original 318, I'd spend my money on a 360. 360 long blocks are still easy to find. Or get a short block and run aluminium heads. All depends on your budget.

This. Just put a 360 (stroked to 408) in my 318 non-numbers car. Full SCAT setup, custom solid roller cam, mild intake and head porting, roller rockers, upgrading valves/springs... I think I paid 7k to have the whole motor built with the cost of the 360.

 

[moparleo]

Fortunately 318 type heads are very inexpensive. Great time to get 73 up heads with hardened exhaust seats. Rebuild or long block time.