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Vacuum question

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Old Aug 19, 2011 | 09:17 AM
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Does anyone know how much vacuum advance is ideal for a 5.7??

Thanks
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Old Aug 19, 2011 | 03:09 PM
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Your question cannot be answered...at least, not in its present form. Much more information needs to be known about the engine and its internal components...specifically heads and cam...before this question could be answered legitimately. Depending on the engine's ability to produce vacuum (very dependent on heads/cam/etc), and the engine's preference for how much vacuum advance is needed for it to idle smoothly and efficiently, the proper vacuum advance can needs to be selected. There are many advance cans, so that a resonable choice can be made for every possible 5.7L engine configuration.
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Old Aug 19, 2011 | 03:31 PM
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trickflow ASM 175cc heads and comp cam with .454 lift.. stock intake and carb
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Old Aug 19, 2011 | 04:40 PM
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I would say in the 8 to 10 degree range on an engine with about 10:1 compression.
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Old Aug 19, 2011 | 05:01 PM
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It doesn't matter what your idle timing is, whats important is getting 36 degrees at 2800 rpms is.
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Old Aug 19, 2011 | 05:08 PM
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He's not asking about idle timing. The question was what total vacuum advance can be run.
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Old Aug 19, 2011 | 05:27 PM
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Originally Posted by MelWff
He's not asking about idle timing. The question was what total vacuum advance can be run.
well Ok
whats important is getting 36 degrees at 2800 rpms.
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Old Aug 19, 2011 | 06:01 PM
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Originally Posted by Vette8182
Does anyone know how much vacuum advance is ideal for a 5.7??

Thanks
The answer to your question is: Take the timing at idle, let's say it's 16*. Take the amount of mechanical advance, let's say it's 20*. Add these two numbers together, and we have 36*. The difference between this number and 52, is where you should aim for with vacuum advance. In this case, it is 16*.


Scott
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