knoking rattling noise 69 gmc truck

1969 CHEVROLET TRUCK
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WISE651
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ok so when i am doing about 40 mph going up a hill lightly steping on the gas i hear a like knocking, rattling noise coming from the engine and it only does it at this time. and i have had my truck (1969 gmc shortbed) for two years now and i have heard this noise before in the past and it went away and now i belive it is getting progessivly worse. i am thinking it could be my valves. i had my exhaust just replaced as the prior one was not good, it had broken pipes and broken headers and i ran it like that for about a year and a half. so i am thinking i could have a burnt valve. please tell me what you think.
Mar 12, 2007 at 8:57 PM
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MIKE H R
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if it was a valve the engine would run rough, have the timing checked, check the plugs and wires. does it sound like a octane ping.
Mar 12, 2007 at 9:20 PM
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WISE651
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no it really doesnt doesnt sound like a ping, but to be honest i am not really sure of what an octane ping would really sound like. and my truck accually runs really good. its just under a load when i am going up a hill, lightly stepping on the gas pedal, it makes a ratting noise coming from the engine. its not really a knocking noise. i dont know, its just so wierd becasue i have never heard anying thing like this. and its not a loud noise. when i give it more gas also, the noise goes away.
today i am going to change the spark plugs and see what happens......

[quote:6883d632b3="M_J_RITZEL"]if it was a valve the engine would run rough, have the timing checked, check the plugs and wires. does it sound like a octane ping.[/quote:6883d632b3]
Mar 13, 2007 at 6:34 PM
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MIKE H R
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does it get louder when you step on the gas? is it sound like rattling loudly in the engine or something knocking. if its a rattling then i would have the plugs wires and timing checked. if its a knocking you would hear it when you are not pulling a load, if that was the case you should have the engine checked
Mar 13, 2007 at 8:18 PM
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