C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

LT1 Knocking noise continued

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Old Mar 6, 2005 | 01:14 PM
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Default LT1 Knocking noise continued

A couple weeks ago I had a knocking noise in the LT1 after a piece of rope broke off in the motor and I turned it over, Well after the motor warms up it went away. Well, yesterday I kept fooling around trying to locate this problem, and when I unpluged the #1 cylinders spark plug while running, the noise went away. Obviously because I am not igniting the cylinder , the noise isnt pronounced. WOuld a compression test show anything? What do you think the most likely thing it could be? Piston? Valve bent?, Rod bearing?
Just preparing myself.
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Old Mar 6, 2005 | 07:35 PM
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Originally Posted by steve40th
A couple weeks ago I had a knocking noise in the LT1 after a piece of rope broke off in the motor and I turned it over, Well after the motor warms up it went away. Well, yesterday I kept fooling around trying to locate this problem, and when I unpluged the #1 cylinders spark plug while running, the noise went away. Obviously because I am not igniting the cylinder , the noise isnt pronounced. WOuld a compression test show anything? What do you think the most likely thing it could be? Piston? Valve bent?, Rod bearing?
Just preparing myself.

Steve I feel for you brother, I am sorry this happened. A cylinder leak down test would reveal more. Let's turn a negative into a positive. A while back you wanted a larger cam, so sell me your Hotcam and buy yourself a GM847 for that monster 396 you have. Then get it dyno tuned and afterward you might actually be happy this happened.
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Old Mar 6, 2005 | 08:17 PM
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http://www.madz28.com/chris847.mpg

Found a sound clip of the GM847 cam. If this doesn't get your juices flowing nothing will. BTW with this cam NO ricer will ever challenge you to a race. LOL
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Old Mar 7, 2005 | 12:02 PM
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Thaks, I need to find out what is wrong first. A New Cam will go in, with lifters, and NEW SPRINGS. When I pull the motor, I need to see if the machine shop here can fix it, ie turn crank? Balance? etc. Motor has very few miles, so a bore wont need to be done.
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Old Mar 7, 2005 | 12:21 PM
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Originally Posted by crheinish
http://www.madz28.com/chris847.mpg

Found a sound clip of the GM847 cam. If this doesn't get your juices flowing nothing will. BTW with this cam NO ricer will ever challenge you to a race. LOL
Now that's a cam lope.
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Old Mar 7, 2005 | 12:42 PM
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Default It may be a simple thing.

It may be something simple. Have you inspected the easy stuff on that cylinder like pushrods, rockers, valves? If not that would be a good start.

I'll admit I haven't read other threads concerning the issue. I am just hoping the best for you.

Best of luck.
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Old Mar 7, 2005 | 12:53 PM
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sounds like a spun bearing to me.
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Old Mar 7, 2005 | 12:53 PM
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so THAT's what an 847 sounds like
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Old Mar 7, 2005 | 01:25 PM
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I checked the valve train, even moved pushrods and rockers to another cylinder. When the motor is running, I can disconnect the plug wire, and the noise goes away. I wam taking the pan of today, and will inspect the #1 cylinder rod bearing. Hopefully it si JUST the bearing, and not the crank too. After the noise started I barely drove it then parked it.
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Old Mar 7, 2005 | 02:10 PM
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That 847 sounds bad-azz!!
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Old Mar 7, 2005 | 02:17 PM
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gee... 396... nice number, but just not good on bearings and rods. the angles are just too steep.

I suspect you will have more problems with that motor than it's worth.
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Old Mar 7, 2005 | 02:31 PM
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You don't already have a 396 do you? Your sig says that you have a 355.
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Old Mar 7, 2005 | 02:40 PM
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I will fix my sig, I thought it was. Thanks
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