 how does the advance on the Distributor work? |
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| jmargush |
 May 16 2014, 03:06 PM
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Senior Member  Group: Members Posts: 501 Joined: 8-June 04 From: Goshen, IN Member No.: 2,176  |
Does anyone know how the vacuum diaphragm on the distributor works?
One side is to retard the timing correct? does the other side advance it as the vacuum drops or changes? Should I have noticeable vacuum on that hose when I pull it of the diaphragm? |
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| r_towle |
May 17 2014, 06:59 AM
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#2
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Custom Member Group: Members Posts: 24,705 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States 
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The vacuum advance helps with off idle stumbling.
At 3500 rpms, and even before that, the mechanical advance starts working by centrifugal force, so as long as both springs are not broken, and the mechanism is working, you get total advance in the end. Vacuum retard helps with run on which is when you are coming to a stop light, the idle takes too long to come back down....when vacuum retard is working, it snaps the advance plates back to zero....so you don't have to wait. You can run without either of them. You tune the car without either hose attached. I have had mixed results tuning with the retard hose....but I was tuning a car for autox and we did not Ike it coming back to idle so quickly...it performed better with some advance still in play between shifts. |
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Posts in this topic
jmargush how does the advance on the Distributor work? May 16 2014, 03:06 PM
Mblizzard See post 18 in this thread.
From the Cap'n so... May 16 2014, 03:13 PM
jmargush
See post 18 in this thread.
From the Cap'n s... May 16 2014, 03:55 PM type47 My only problem with the Cap'ns explanation is... May 16 2014, 03:34 PM Mblizzard
My only problem with the Cap'ns explanation i... May 16 2014, 04:07 PM Dave_Darling The 74 cars, and some later ones, do not have vacu... May 16 2014, 04:15 PM Bob L. As I see it, you will get less total advance but e... May 16 2014, 04:16 PM |
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