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Chilly178 · 11-23-2017, 07:41 PM

Hello I'm back with an update. So I drained the oil out and I also cut open the oil filter with a pair of tin snips. The filter and oil had quite a bit of metal shavings. I put a magnet in the oil and picked up a ton of metal shavings. So my guess is one of the cam lobes is worn flat. I'll take off the manifold and dig deeper when I get some more time. So right now the plan is to buy a GM performance crate engine, either the L31-R or the HT 383 depending on how much I have to spend. Only thing I don't like about the L31-R is the electronic fuel pump, but then the 383 is over double the price. I wish there was a good middle ground by GM that had a one piece rear main seal, hydraulic roller cam, vortec heads, and uses a mechanical fuel pump.

11-23-2017, 07:41 PM	#35
Chilly178 Registered User Join Date: May 2016 Location: Green Bay, WI Posts: 129	Re: Any idea on what this knocking is 72 C20 350 Hello I'm back with an update. So I drained the oil out and I also cut open the oil filter with a pair of tin snips. The filter and oil had quite a bit of metal shavings. I put a magnet in the oil and picked up a ton of metal shavings. So my guess is one of the cam lobes is worn flat. I'll take off the manifold and dig deeper when I get some more time. So right now the plan is to buy a GM performance crate engine, either the L31-R or the HT 383 depending on how much I have to spend. Only thing I don't like about the L31-R is the electronic fuel pump, but then the 383 is over double the price. I wish there was a good middle ground by GM that had a one piece rear main seal, hydraulic roller cam, vortec heads, and uses a mechanical fuel pump.