What caused this carnage?

[thehueypilot]

What are the chances of finding the pulg that came from that hole ? Does it have black specs on it ? Do any of them ?

The plug is coated with a grey, metal finish from the aluminum that melted and deposited on it and the exhaust valve. The rest of the plugs have a black/brown deposits on them. I still think it was a piston defect that just now showed up, but I am having trouble convicing CHP of that.

 

[180 Out]

You CAN get detonation that you can't hear. But it wouldn't happen to just one cylinder. Check the other plugs with a magnifying glass, for bits of aluminum.

I will make a fearless prediction and say that you will get no relief from CHP, so don't waste a lot of time or energy on them. "It ran for over two years with no issues." I've heard that CHP will give you no relief if a connecting rod lets go in the first month, much less two years.

Here's an excellent article regarding the avoidance of detonation: http://www.popularhotrodding.com/enginemasters/articles/hardcore/0311em_power_squeeze/index.html

Good luck!

 

[strange65]

Burnt - out blow hole

Thats whats called a burnt-out blow hole it can be caused by :
too lean carb jetting, too far advanced ignition timing, too hot of a spark plug range, too high of a compression ratio, too low octane fuel. The piston overheated, Since the piston temperature is higher on the exhaust side , thats the side thats usually gets damaged.

 

[brianj5600]

I've heard of some engine builders running more gap on bottom to prevent exessive pressure between rings. It sounded weird to me, but could explain why the ring was lifted. I don't know if I would use those pistons. It is not the first one I have seen that failed in the same spot. Chunks of metal in the CC is a scary thing. It could wipe out the head , block, rod, crank, cam, oil pan, etc.

 

[thehueypilot]

Thats whats called a burnt-out blow hole it can be caused by :
too lean carb jetting, too far advanced ignition timing, too hot of a spark plug range, too high of a compression ratio, too low octane fuel. The piston overheated, Since the piston temperature is higher on the exhaust side , thats the side thats usually gets damaged.

It blew out on the intake side and not the exhaust side. CHP is sending me a new balanced piston and ring for $43. One lessened learned from a stroker motor is that the rotating assembly is special so changing all the pistons would greatly hurt the pocket book. They did call me back in a timely manner and resolved my issues to get this thing going again, but...................will I give them repeat business? TBD

 

[gp001]

I'll just add my $0.02 about CHP. I have had my 347 in my car for almost 6 years. Close to 30k HARD miles (not a daily driver). And I have had ZERO problems.

JMO, YMMV

 

[Wootdog]

how many rpms was it running?

 

[Wootdog]

it happen on down stroke ck heads predetonaion maybe?

 

[thehueypilot]

how many rpms was it running?

I usally shift around 6k.