What caused this carnage?

thehueypilot · Jan 5, 2006

10secgoal said:
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 · Jan 5, 2006

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 · Jan 5, 2006

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 · Jan 5, 2006

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 · Jan 6, 2006

strange65 said:
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 · Jan 6, 2006

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 · Jan 6, 2006

how many rpms was it running?

Wootdog · Jan 6, 2006

it happen on down stroke ck heads predetonaion maybe?

thehueypilot · Jan 8, 2006

Wootdog said:
how many rpms was it running?

I usally shift around 6k.

What caused this carnage?

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