Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: topside]
#718010
06/07/10 12:07 AM
06/07/10 12:07 AM
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Joined: Jun 2006
Posts: 5,155 CT
GTX MATT
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Joined: Jun 2006
Posts: 5,155
CT
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I say manifold vacuum but alot of people will disagree with me. If you want it to idle better and you tune your mechanical advance correctly use manifold vacuum. Ported vacuum is basically doing the same thing that your mechanical advance does. Nothing at idle and more advance at WOT/high rpms.
Now I need to pin those needles, got to feel that heat Hear my motor screamin while I'm tearin up the street
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: NV69B7RR]
#718011
06/07/10 01:27 AM
06/07/10 01:27 AM
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Joined: Dec 2003
Posts: 5,314 Carstairs, Alberta, Canada
dave571
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Joined: Dec 2003
Posts: 5,314
Carstairs, Alberta, Canada
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Ported is correct. Manifold ads timing when you don't need it. Vacuum advance is to give more advance at light cruise to improve economy. Ported vacuum accomplishes this, and it's how the factory dist is designed to work. IMHO especially on a stroker, you should be running a dist that has been set up to use the most initial timing you can get away with, and bring in the mechanical when you need it.
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: dave571]
#718012
06/07/10 07:16 AM
06/07/10 07:16 AM
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Joined: Sep 2004
Posts: 1,226 Cookeville
Chilort
Will Work For Mopars
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Will Work For Mopars
Joined: Sep 2004
Posts: 1,226
Cookeville
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: GTX MATT]
#718013
06/07/10 07:28 AM
06/07/10 07:28 AM
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Joined: Mar 2008
Posts: 5,746 Ontario, Canada
Dodgem
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Ontario, Canada
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Quote:
I say manifold vacuum but alot of people will disagree with me. If you want it to idle better and you tune your mechanical advance correctly use manifold vacuum. Ported vacuum is basically doing the same thing that your mechanical advance does. Nothing at idle and more advance at WOT/high rpms.
Anyone who would try to get better idle this way is an idiot!
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: NV69B7RR]
#718016
06/07/10 07:34 PM
06/07/10 07:34 PM
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Joined: Jan 2003
Posts: 25,618 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,618
Rio Linda, CA
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My advice....ignore all the advice and try it both ways, see which works best for your setup.
By "try it both ways" I don't mean just move the hose, tune it around both ways and see which drives the best.
The INTERNET, the MISinformation superhighway
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: Dodgem]
#718018
06/08/10 12:28 AM
06/08/10 12:28 AM
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Joined: May 2003
Posts: 6,545 Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
Posts: 6,545
Downtown Roebuck Ont
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You might want to "red" that book again. If you set your mechanical at 35 total, the vacuum advance only adds to it at part throttle ie 35*+15* vac = 50*. At WOT it will still be 35. FYI ALL cars with vacuum advance use manifold vacuum. The only difference is ported shuts off the vacuum when the throttle is closed so no advance at idle. Strictly an emission control deal.
Kevin
Last edited by Twostick; 06/08/10 12:52 AM.
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: moparts]
#718022
06/08/10 08:42 AM
06/08/10 08:42 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
And now you're both wrong. The only difference between ported and manifold is ported shuts it off at idle. Crack the throttle and they are the same. Easy test, get 2 vacuum gauges and hook them up, 1 ported 1 manifold and you will be enlightened
Kevin
Thank You
On a pre emission car the vacuum was hooked up at the base of the carb,
The vacuum advance is on top of your normal timing settings, gives you that 50 plus degrees of timing at light throttle to help with gas mileage
All timing is set with the advanced unhooked
hence my quest why even hook it up? Isn't this a 512cid wedge? Set it for performance and have fun.
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: hooziewhatsit]
#718024
06/08/10 02:39 PM
06/08/10 02:39 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
hence my quest why even hook it up? Isn't this a 512cid wedge? Set it for performance and have fun.
And why not hook it up? If tuned correctly you won't know it's there, except for the mileage increases.
doubt you'll see much. Not like it's going to easy to kep ur foot out of 512 cubic inches.. I couldn't anyway
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: Mr.Yuck]
#718025
06/08/10 03:30 PM
06/08/10 03:30 PM
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Joined: Jan 2003
Posts: 3,967 S.I. N.Y.
1MYTGTX
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I just had my dizzy recurved again by Don at FBO. The reason I had it done again is because this time I NEEDED to add back the vacuum advance to get my 440 to run right with the stock cast iron manifold & correct 4640SA Carter AVS carb.
Don added the advance mech & curved it to use MANIFOLD vacuum to give me 34º all in by 3400 rpm at WOT. This eliminates the possibility of detonation at high RPM's due to overadvancing.
1MYTGTX
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Re: 440 Vacuum advance, hook up ported or constant vacuum?
[Re: 1MYTGTX]
#718027
06/08/10 06:02 PM
06/08/10 06:02 PM
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Joined: Feb 2003
Posts: 10,178 Someplace you aren't
SomeCarGuy
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 10,178
Someplace you aren't
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Quote:
I just had my dizzy recurved again by Don at FBO. The reason I had it done again is because this time I NEEDED to add back the vacuum advance to get my 440 to run right with the stock cast iron manifold & correct 4640SA Carter AVS carb.
Don added the advance mech & curved it to use MANIFOLD vacuum to give me 34º all in by 3400 rpm at WOT. This eliminates the possibility of detonation at high RPM's due to overadvancing.
That doesn't seem right at all there. 3400 RPM, vaccum advance to get 34 degrees, at WOT.
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