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Old 04-12-2008, 05:28 PM
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383 Knock

So i finally got the 383 started and was tinkering on it today since it is broken in and i'm trying to time and tune it right now. Anyway, i'm starting to notice a knock when it is at idle and i just punch the gas to like 3000+ rpms. It is just one solid knock like you were hitting your fist against your palm. I think it might be something like the engine is scavenging for fuel. My other thought was it is detonating when i punch it, but how loud is the ping when it detonates? I know it is not metal to metal contact.

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Old 04-12-2008, 05:53 PM
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Quote:
Originally Posted by mightycarlo10
So i finally got the 383 started and was tinkering on it today since it is broken in and i'm trying to time and tune it right now. Anyway, i'm starting to notice a knock when it is at idle and i just punch the gas to like 3000+ rpms. It is just one solid knock like you were hitting your fist against your palm. I think it might be something like the engine is scavenging for fuel. My other thought was it is detonating when i punch it, but how loud is the ping when it detonates? I know it is not metal to metal contact.
Does it sound like the opening of a cold beverage can(preferably a Bud can) or after you are done drinking it and rocking the opening tab loose to break it off? Pinging sound more like the later, valve adjustment might sound more like the opening.
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Old 04-12-2008, 06:05 PM
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Good terminology. It sounds like opening the can, but it's just one solid knock. I think i might be one tooth off with my distributor so it could be detonating.
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Old 04-17-2008, 09:23 PM
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Alright i fixed that noise, but found another. This one is possibly quite serious. I put a screwdriver on top of the intake of the #1 cylinder and there is a knock that gets quicker and louder with engine load. It is more prominent at the top of the intake than towards the oil pan. It is like a tink-tink-tink-tink... but is not like a loose rocker. So based on that i think it could be one of these:

1) Piston Slap- But the pistons i have are hypers and the machine tolerances were pretty close.

2) Valvetrain noise other than rockers

3) Broken Ring Land

4) Worn Rod Bearing


Now when we first started the motor (2 weeks ago) my friend said that he heard a noise from the front of the engine but didnt think anything of it because everything was new. He heard the same noise today and decided that maybe he should tell me or do something about it. So the engine has been doing it during/since first start up.

I think what i am going to do is drive the car and monitor the noise everyday to see if it is getting louder or whatnot. The engine has real god oil pressure and the temp is normal so we'll see what happens.

What do you guys think about what this noise might be?
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Old 04-17-2008, 09:33 PM
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When you assembled the motor, what was your crankshaft thrust? Do you have a cam button, and if so, what is it's clearance to the timing cover?
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Old 04-17-2008, 09:34 PM
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Washer or nut on top of the piston, most likely a 5/16 lock washer, or thin nut like used on the crank post of the starter. Pull that plug and look in the hole you might see it embedded in the top of the piston just under the outer diameter of the intake valve.
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Old 04-17-2008, 09:45 PM
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68Nova- I thought of the crankshaft play too, but forgot to add that. I cant remember what it was, but it was in check. Could it get messed up from the engine install or something?

Carsavvy- Lets hope its not that.
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Old 04-17-2008, 11:14 PM
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Not likely, unless you dropped it on it's nose or tail.

Any chance your valve cover is mounted low and the rocker is tapping the intake side? You can loosen it and shift it upwards, easy thing to try.
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Old 04-17-2008, 11:51 PM
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Carsavvy- Lets hope its not that.[/QUOTE]

I heard this noise after going to eat dinner and went back to work to light off and finish a 454BBC installation in a truck. A co-worker locked up while I was gone. To keep it short; The next morning I had the head off and was sharpening up my butcher knife when he walked in. He turned around and left and someone else picked up his tool box that same day. By the way it bent the ground electrode on the spark plug too.


It was a 5/16 lock washer.

Last edited by carsavvycook; 04-17-2008 at 11:56 PM. Reason: addition
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