Thread: 400 sbc knock

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Look at the pistons real close see if you have a crack and check to see if wrist pin fit is too loose .....ted

Had a new motor broke in on a test stand, and put it in the car, developed a slight "tick" down low, I revved it up and she came apart badly, everything was good but the balanced rotating assembly I had purchased had too small wrist pins in it, they where slightly hitting the cylinder wall and ended up gouging the cylinder (cracked piston, bent valves, cracked block everything bad), never checked it since they where assembled and balanced together from a factory machine shop. Good news was they came from a very reputable company, I contacted them and they had knew about the problem and they picked up the bill for a whole new motor. Don't assume new parts are always perfect! Best of luck Matthyj