Vacuum question

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Aug 19, 2011 | 09:17 AM

Vette8182

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From: Worcester MA

Vacuum question

Does anyone know how much vacuum advance is ideal for a 5.7??

Thanks

Aug 19, 2011 | 03:09 PM

7T1vette

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From: Crossville TN

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.

Aug 19, 2011 | 03:31 PM

Vette8182

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From: Worcester MA

trickflow ASM 175cc heads and comp cam with .454 lift.. stock intake and carb

Aug 19, 2011 | 04:40 PM

MelWff

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I would say in the 8 to 10 degree range on an engine with about 10:1 compression.

Aug 19, 2011 | 05:01 PM

Tim H

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From: Southern Indiana

It doesn't matter what your idle timing is, whats important is getting 36 degrees at 2800 rpms is.

Aug 19, 2011 | 05:08 PM

MelWff

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He's not asking about idle timing. The question was what total vacuum advance can be run.

Aug 19, 2011 | 05:27 PM

Tim H

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From: Southern Indiana

Quote:

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.

Aug 19, 2011 | 06:01 PM

scottyp99

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From: Oxford MA-----You just lost the game!!!!

Quote:

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