This is what's wrong...

[caci]

Tore down the Sy engine today, after progressively louder knocking:

Broken 1st rings on 3 & 5.

Spun # 3 main bearing - lots of copper showing on the others.

So, I guess I'll be safe and try a new crank, line bore splayed caps, zero-gap rings and start from scratch.

Any recommendations on non-$2500-forged-crankshafts?

 

[4C FED]

Re: This is what's wrong...

Have the crank journals measured first before you toss it. Maybe you can turn it .010 under. If it can't be turned .010 under, there are several vendors on here (RPM, Turbo Time, John Waller) that can get you a nitrited crank.

Broken rings, spun & hammered bearings sound like you had lots of detonation. Make sure you get the tune squared away before you start having fun after the rebuild.