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Odd Vibration

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Old Jul 18, 2020 | 05:04 PM
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Default Odd Vibration

Odd vibration starting around 3300 and never stops all the way up to 5000. The vibration, for a lack of better description seems to come in waves. It's not really dependent on engine speed or even road speed. In other words, I could do 80 and not feel it as the revs will be under 3300. The wave is about a 30 cycles per minute if I were to estimate. Each vibe wave is high frequency and lasts for 1 sec or so...until the next one comes.

I just did some work on the engine - Crane 274H06 cam, lifters, 1.5 rockers, timing chain, harmonic balancer. The rest is bone stock base 350. This may be related to my other post about the fluctuating vacuum gauge as it might be a burnt valve...but I wonder if it would cause such as vibration.

Any ideas?

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Old Jul 18, 2020 | 05:29 PM
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You really need to tell us what year to start. Did it do this before the work? What kind of ignition system? I would run a compression check first, then take a look at the ignition system. Have you taken a look at the plugs to see if there's one or more that are different? Just a starting point. Are the plugs the correct ones, and are they gapped correctly?

Last edited by Mrvettenick; Jul 18, 2020 at 05:32 PM.
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Old Jul 18, 2020 | 05:31 PM
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Sorry, good questions. Yes, it did it before the work. Plugs are textbook perfect. Stock ignition. Have not run compression test. 1969 base 350 4-speed.
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Old Jul 18, 2020 | 05:42 PM
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What balancer did you install?
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Old Jul 18, 2020 | 05:43 PM
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Standard GM 8" replacement. Had an 8" when I got the car.
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