Total advance, initial, mechanical and vaccum advance Can anyone break it down Please - Hot Rod Forum : Hotrodders Bulletin Board
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Old 09-07-2007, 05:31 PM
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Total advance, initial, mechanical and vaccum advance Can anyone break it down Please

This is all i know and i dont really understand what it means Total advance for our purposes is initial advance plus mechanical advance. Disregard vacuum advance for now.
Just want to know how to adjust properly

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Old 09-07-2007, 05:42 PM
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You didn't say what motor, but we'll assume a small block Chevy. You would want somewhere between 32 and 36 degrees of initial + centrifugal advance, depending on the combustion chamber size and shape.

Initial is what you dial in at the crank with your timing light and would be somewhere between 4 degrees and 20 degrees. Most guys use around 12 at the crank initial advance. This is with the vacuum cannister hose disconnected at the cannister and a golf tee stuck in the hose.

Centrifugal would be what the distributor weights would swing out to add to the initial advance and would be in the neighborhood of 20 to 26 degrees. You can buy inexpensive weights and springs to tailor this anywhere you want it. To bulletproof it, take it to a shop that has a distributor machine and have them tell you the exact advance you've put in as well as where the total advance comes in in crankshaft rpm's.

So, to get, for instance, 36 degrees initial and centrifugal, you might dial in 12 degrees initial at the crank and put 24 degrees centrifugal advance into the distributor. For best performance in a hot street motor, you might want the full advance of 36 degrees all in by 2,600 to 3,200 rpm's, depending on the weight of the car and other factors.

Vacuum advance is added to this at cruise speeds for additional fuel mileage and might be another 10 to 15 degrees for a total initial, centrifugal and vacuum of around 50 degrees.

Oops, I didn't see that you had two threads going on this same subject. Hope I didn't step on anybody.

Last edited by techinspector1; 09-07-2007 at 05:50 PM.
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Old 09-07-2007, 07:25 PM
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Total advance

Techinspector1's explanation sounds pretty good. I may have confused you by calling centrifugal advance mechanical advance. Just different East coast/West coast terminology I guess....lol.
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