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**Steeveedee** · 09-12-2017, 03:21 PM

Sounds almost like an exhaust leak; it's not all that hard a sound. Try using a piece of garden hose like a stethoscope to help locate the source. It's in the top end, for sure, though, from the sound of it, it's at valve train speed.

09-12-2017, 03:21 PM	#5
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,081	Re: Any idea on what this knocking is 72 C20 350 Sounds almost like an exhaust leak; it's not all that hard a sound. Try using a piece of garden hose like a stethoscope to help locate the source. It's in the top end, for sure, though, from the sound of it, it's at valve train speed. __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA