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ZZ4 Knocking noise at idle (Help!)

 
Old 07-07-2019, 11:25 PM
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ZZ4 68 Nova
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Default ZZ4 Knocking noise at idle (Help!)

My ZZ4 (gm 350) crate motor has had an irregular sounding knocking noise at idle lately and i cannot figure out what is causing it. I have changed my plugs, plug wires, and even fiddled around with the distributor and timing but the knock is still there, i also changed the lifters in the car just before i changed the other listed parts, but i changed those because i also had a noisy lifter as well as the knocking noise (just going over all the work ive done recently in case it helps).

The noise only occurs at low rpm and has no pattern, knocking at random times, sometimes its frequent and fast paced and other times it stays quiet for a few seconds. Once i rev the car up to about 1000 - 1200 rpm their is no more knocking and the engine runs perfectly.

Video of it idling at running temp (approx 800rpm): https://www.youtube.com/watch?v=29Wy...ature=youtu.be
Knock is much easier heard at high volume

Any suggestions or help is appreciated, as the "unsolvable" issue is driving me and my dad nuts haha. Thanks.

Last edited by ZZ4 68 Nova; 07-12-2019 at 05:35 PM.
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Old 07-08-2019, 09:13 AM
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CamaroAJ
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Whats the oil pressure at idle? And at 1200?
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Old 07-09-2019, 04:08 PM
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just went out and checked, @ idle the lowest it would go was 32psi, and @ 1200rpm it was up to 48psi. Running 20-50 non synthetic oil.

I uploaded a youtube video of the car idling, link is in the original post.
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