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Vaccuum at idle on 1945 carb..
https://slantsix.org/forum/viewtopic.php?t=38333		 Page 2 of 2
Author:  SlantSixDan [ Sun Dec 20, 2009 10:57 pm ]
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Vacuum advance depends only on engine load and throttle position. Centrifugal advance depends only on engine speed. With the engine running at high speed, the throttle's going to be pretty widely open, so there'll be little manifold vacuum and therefore little vacuum advance.
Author:  Aggressive Ted [ Mon Dec 21, 2009 9:18 am ]
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Quote:
Your last post has me a little confused (not uncommon for me )LOL. Should your vacuum advance start to come in right off of idle ? I would assume it would until the centrifugal advance starts to kick in ? At higher RPM when centrifugal advance really comes in, is the vacuum advance still advancing the timing in addition to centrifugal or is in inactive by then ?
(again thank you for the education here)
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Should your vacuum advance start to come in right off of idle ?
Yes, the engine will have the best response if it does. The vacuum advance pod can be tuned with a 3/32 alen wrench down it's snout. I tuned mine to 3 turns out so it won't come on at idle.
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I would assume it would until the centrifugal advance starts to kick in ?
Yes, and that can be tuned with various springs from "bigslant6fan". He sells a nice kit.
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is the vacuum advance still advancing the timing in addition to centrifugal or is in inactive by then?
No, it is out of the picture.....inactive.
Author:  slanty6 [ Tue Dec 22, 2009 11:29 pm ]
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Dan and Ted, thank you both so much for your replies. I am starting to undestand a bit better how the timing advances work on a car. I thought it was like initial +vacuum +centrifugal. I now see that is initial + a synergy of vacuum and centrifugal combined depending on the speed, load, and throttle opening. Hot damn I'm getting this stuff down.. Thank you again !!
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