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Old 11-21-2004, 11:55 PM   #1
CHEVY & GMC FOREVER
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Another Question

Hello everybody, as some of you may know I recently bought a 1969 CST-10
pickup with a 350. Anyway I was doing some inspecting of the engine to day particularly the carb because there is this sort of a rattle in the engine when I step on it, i tried lowering the timing and lowering with the idle and stuff but nothing seems to work, HELP!!!!
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Old 11-22-2004, 01:47 AM   #2
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Are You Using High Octane Gasoline?

You may want to give that a try as it is recommended in the owners manual. Assuming that what you are hearing is preignition - which is what your description sounds like. Be sure to set your timing with a light and ensure the vacuum advance is disconnected when setting it. Also ensure that the vacuum advance is on a ported vacuum source. That is to say that at idle there is no vacuum present and the vacuum becomes increasingly more with an increase in engine speed. An engine that is running too hot will also suffer preignition. Another cause of preignition could be a buildup of carbon in the cylinders increasing the compression ratio. I would start with the high octane gas and checking the vacuum advance.
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Old 11-22-2004, 07:54 AM   #3
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this generally works except for real high compression.
ported vacuum, initial advance @ 10-12*, MSD 6A or 6AL.
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