Engine Teardown Analysis and Questions (pics)
Engine Teardown Analysis and Questions (pics) Hey all,
For years my car has suffered from some smoking under deceleration. In an effort to fix this I was replacing the valve stem seals when I noticed that the #7 cylinder was not holding pressure. I pulled the motor and found this:
This is a stock shortblock with AFR heads, around 10:1 SCR. Never revs past 6800. My tuner set up the car for reliability as I run at the track often. What I'm wondering is what the most likely cause is for cracking a piston like this. I'm taking delivery of a Katech 427 next month and I want to make sure this doesn't happen again.
Thanks in advance to any helpful replies!
-ch
For years my car has suffered from some smoking under deceleration. In an effort to fix this I was replacing the valve stem seals when I noticed that the #7 cylinder was not holding pressure. I pulled the motor and found this:
This is a stock shortblock with AFR heads, around 10:1 SCR. Never revs past 6800. My tuner set up the car for reliability as I run at the track often. What I'm wondering is what the most likely cause is for cracking a piston like this. I'm taking delivery of a Katech 427 next month and I want to make sure this doesn't happen again.
Thanks in advance to any helpful replies!
-ch
Last edited by hyperion; Mar 30, 2009 at 03:09 PM.
TECH Fanatic
Joined: Feb 2004
Posts: 1,259
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From: Lexington, KY
That is somewhat common, and almost always #7. Don't know why though. One thing I have read that makes some sense is the possibility that the intake manifold flows slightly more air to #7, which would make this cylinder run leaner than the rest.
Thanks for the replies! No power adders, and runs on CA 91 octane pump fuel. But it's somewhat comforting (I guess) that #7 is the common failure.
Is this type of failure usually due to heat or detonation?
-ch
Is this type of failure usually due to heat or detonation?
-ch
Like dave x said, it sorta common on the #7. I have read too that the the # 7 is the problem hole with running lean due to the intake design. If your 427 has forged pistons in it, you that should fix the problem.
